Wireless & RF Magazine: February 2015

The Future of

Wireless Cypress’ PSoC Products Enable Next Generation IoT Applications Interview with John Weil – VP of Marketing for the Programmable Systems Division at Cypress Semiconductor Corp.

Testing • Compliance with a Microwave

• Wide World of

Regulatory Testing

February 2015

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CONTENTS

CONTENTS

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PROJECT Quick and Easy Bench Test Using a Microwave Oven for Pre-compliance Testing

TECH REPORT Electromagnetic Conformance Testing

The Wide World of Regulatory Testing LISTED

INDUSTRY INTERVIEW

12 14 28

The Future of Wireless Interview with John Weil, Cypress Semiconductor Corp.

TECH SERIES

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Wi GaN: Radiated EMI Comparison in Wireless Power Transfer

Figure 1: Radiated EMI system Overview.

The PSoC® 4 is like a Swiss Army Knife; it solves a lot of problems without it being designed for any one particular problem...pg. 28

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Pre-compliance

TESTING with a Microwave OVEN?

By Alan Lowne, Saelig Co. Inc.

4

PROJECT

“Quick-and-dirty� bench testing is becoming more necessary than ever for discovering if your new product design stands a chance of passing the required emissions standards. Booking time and space in an approved, certified test facility to make sure your new product meets EMI emissions limits is very expensive, but it’s even more costly if your product fails. This would mean back to the bench to fix unwanted radiation, and return for a retest.

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Pre-compliance testing has fortunately now become extremely affordable and early detection can provide a good idea of problems before they get very expensive to fix.

Many designers and manufacturers don’t have their own RF test lab with an EMI-proof chamber or even the matching expensive RF test-gear.

However, pre-compliance testing has fortunately now become extremely affordable and early detection can provide a good idea of problems before they get very expensive to fix. Standards vary by country, but common EMC regulations for USA are described in FCC Part 15, with subsections depending on whether the product is a consumer item or not. For Europe’s CE mark, EN55011 is the common standard, while some products have even stricter requirements.

It is now quite inexpensive to purchase a useful RF spectrum analyzer with associated near-field probes or antennas so you can get a first look at basic EMC/EMI problems. Very affordable spectrum analyzers are now available—even as small as a USB thumb drive (see Figure 1), which can be connected to a Windows PC or tablet for operation. Fighting EMI problems with a convenient set of sniffer probes— which look a bit like children’s bubble wands—can quickly find both the sources of problem radiation, and the success of proposed quick fixes. While it’s true that the probes can disturb the field being measured (bringing added capacitance in proximity to an unwanted

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oscillator), experience will reveal how useful and valuable this EMI tool can be.

Sniffer probes can also be used with digital oscilloscopes using the scope’s FFT spectrum analyzer setting, but oscilloscopes are often not sensitive enough for much useful information.

Shielded enclosures—either benchtop metal boxes or quick-erecting portable EMI tents—are useful for excluding ambient radiation and are well within the economical reach of most companies.

If you can’t afford a shielded box, you may already have something suitable nearby: a non-working microwave oven. Not only does the oven enclosure make for a suitable shielding box, but you may even be able to make use of its manually-moved turntable.

Provisions will need to be made for antenna and power wires to exit the oven, however, so that may be the end of its normal use.

Small sniffer probes can be used for near-field testing or a wide-band antenna can be used for a 3-meter field test. This should preferably be done inside an EMI tent (see Figure 3) to avoid interference from outside sources and power lines.

A log-periodic antenna is suited to frequencies below 1GHz, while a horn antenna should be used for higher frequencies.

PROJECT You can often quickly discover the source of EMI emissions with near-field probes (see Figure 2). Near-field magnetic (H-field) and electric (E-field) probes let you detect the origin of EMI problems—whether they be particular circuit layouts, cables, or shielding issues. H-field probes use a conductive loop to detect magnetic fields produced by circuit board signals or switching power supplies. The probes produce a voltage corresponding to the magnetic field in front of the loop. To find emissions on individual pins or PCB traces, you can use E-field probes in direct contact with circuit traces. More than one size of H-field probe may help you evaluate emissions. Probe kits often include a few sizes of E- and H-field probes.

Openings in enclosures and shielding cans can allow emissions to escape and cause current to flow in surrounding metal enclosures. Closing gaps with EMI gaskets or improving soldering techniques may reduce the offending signal. You can use an H-field probe to compare fixes ‘before and after’ inside an enclosure, or a cable’s RF energy that’s picked up from the source because of poor connector shielding. A near-field probe will help identify a cable that’s acting as a radiating antenna. Once you find that cable, you should use current probes around the cable to measure common-mode current that causes emissions. A dipole antenna will reveal far-field emissions and is useful for checking fixes that produce a drop in emissions. Then, you’re ready to perform another round of pre-compliance tests.

Figure 1. Near-field probe testing with USB Spectrum Analyzer.

Figure 2.

Near-field Probe Set.

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After you discover an unwanted radiator, modifying the layout or circuit can be challenging. To improve these EMC issues, you can do one of the following: change the IC or component, add capacitors or inductors, change the PCB layout, move a trace to another layer instead of top or bottom layer, increase the grounding scheme, add a shielding can, or redesign the PCB using a multilayer board with ground planes on the outermost layers.

A gap in shielding cans will cause unwanted emissions. Changing the shielding configuration or soldering points can reduce the radiation. Typical problems that might be found include bypass capacitors too far away from ICs, poor power and ground tracks showing show ringing, gaps in shielding, layout issues, etc. When RF emission emanates from power lines, adding an inductor or ferrite bead in the power

Figure 4. Microwave Oven used as a shielded box.

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The frugal solution of modifying an old microwave oven may be good enough to serve as a competent shielded box that can make somewhat calibrated measurements.

track may be all that’s needed. Clock lines are often another emission source at low frequency, so avoid long PCB clock traces on an outside layer.

A shielded box or tent is certainly a cheaper alternative to an RF chamber, but the frugal solution of modifying an old microwave oven may be good enough to serve as a competent shielded box that can make somewhat calibrated measurements (see Figure 4). In order to approximately calibrate the level of emissions (to estimate a rough order of magnitude of the problem) put two antennas into the shielding box, one connected to a RF signal generator (“emitter”), another antenna (“receiver”) connected to the external Spectrum Analyzer (“SA”). Set the RF signal generator output level at Lref (-40dBm), this antenna will simulate

PROJECT the unit under test (UUT) emission at shielding box. The SA will receive the signal from the antenna with the Lref signal. Test the signal level and record it as reference Sref (here Sref=-65dBm).

Then remove the emitting antenna, and put the UUT into the shielding box. Test

throughout the wavelengths of interest, and compare the signal level with Sref.

If the signal is larger than Sref, there is a problem. If the signal is close to the Sref, it may still require attention. Record the frequency of each troublesome emission point, and then investigate them afterwards using a near-field test probe.

Figure 3. Fast-up EMI shielded tent.

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Figure 5. RF Spectrum Display on PC before fix.

Figure 6. RF Spectrum Display on PC after fix.

Near-field Testing with a Spectrum Analyzer

About the Author

From the shielded box tests, you can get an idea of which frequencies will not pass or be marginal. For frequencies greater than 1GHz, stub probes can be helpful; lower than 100MHz, a 40mm loop probe or 15mm loop probe is the tool to use. If the frequency is between 100MHz to 1GHz, use both a stub and a loop probe. Try moving the probe while positioned close to the circuit and find the biggest signal.

British-born Alan Lowne is CEO of Saelig Co. Inc. an importing distributor of unique test and measurement products from around the world. Previously an electronics design engineer with a multinational company, he founded Saelig (which means “happy, prosperous, and blessed”) in 1988 in Rochester, NY. Saelig has a growing reputation for finding and sourcing easy-to-use control and instrumentation products.

The professional RF test lab will be using a turning table which will be able to find emission from every possible direction.

But after you’ve done all your homegrown bench-top tests, making sure that unwanted emissions are small, you can send your product to the RF test lab with increased confidence.

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Electromagnetic

Conformance

TESTING 12

TECH REPORT

O

ver the last century, the use of the electromagnetic spectrum has undergone a monumental change. What was, at the end of the 1800s, an unregulated, sparsely populated band of electromagnetic waves has today become a highly regulated, extremely saturated region. All wireless communications today need to fit into their appropriated portion of the spectrum, whether it is for television, cell phones, military communications, or amateurs. In the United States, the Federal Communication Commission (FCC) was formed in 1934 to regulate all wired and wireless communications and as a part of that regulation,

they require testing on certain products. This ensures that the products have achieved electromagnetic conformance (EMC), indicating conformance with the requirements mandated by the FCC. If a device, whether intentionally radiating or not, is encroaching into certain bands and creating interference, there can be serious performance issues and legal consequences.

Each country has its own entity, similar in function to the FCC, that has its own unique requirements and thresholds. It is essential to understand the concept of electromagnetic interference (EMI), know what the conformance tests for your market entail, and see if your products require them.

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Sharp Edges Mean More Emissions

You may sometimes hear the terms EMC and EMI used interchangeably; however, they are distinctly different.

Electromagnetic interference is an occurrence that describes the radiation of electromagnetic waves and the effect on the recipients of those waves. This interference can be purposely generated by man-made objects, such as radios or wi-fi, or as an unwanted byproduct, such as spark generators in cars, or by natural phenomena, such as lightning or solar wind. EMI, at its most basic, is the result of voltage or current changing quickly and, as a result, creating spikes of radio energy. EMC, on the other hand, is simply a reference to whether or not a product acts appropriately when dealing with EMI. For our purposes,

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EMC will refer to conformance to FCC’s Part 15. Most consumer products fall under Part 15 as it is specific to products that emit electromagnetic energy but do not require a license to operate.

EMC can be broken down into two separate categories - emissions and immunity. A product needs to demonstrate that it will not emit EMI above the required threshold and that it is immune to receiving certain amounts of interference without affecting operation.

In this regard, the FCC only requires testing on emissions, however, CE marking for the European market requires both emissions and immunity testing.

While immunity testing is not required for the FCC, the statement found on every

TECH REPORT

Emissions

FCC certified product addresses both: This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference, and 2. This device must accept any interference received, including interference that may cause undesired operation.

There are a series of tests which confirm that the emissions are within limits as well as separate tests to confirm the operation of the device under extremely harsh electromagnetic conditions. These tests are performed by accredited third-party companies on behalf of the FCC in controlled lab environments, special testing chambers, or in very remote open air locations.

Immunity

The facilities that are used for EMC testing fall under one of two categories, an anechoic chamber or an open area testing site (OATS). Anechoic chambers are specialized chambers that vary wildly in size with the smallest chambers being approximately 3-meters square with the largest at over 20-meters tall and 80- meters long, capable of fitting full-sized cargo planes. They are lined with special materials that absorb electromagnetic energy, effectively isolating the device under test (DUT) from external sources. For emissions, this allows sensitive detection equipment to detect the output of the DUT without the concern of contamination from external sources. For immunity, it also allows greater control over what the DUT is subjected to while also providing a shield for the testers against the high powered emissions. OATS are falling out of favor as they generally provide less favorable testing conditions. Testing

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is weather dependent, and there is no shielding during immunity testing, which requires a special license for operation.

When testing emissions, either in an anechoic chamber or an OATS, the DUT is placed on a table and set up in the least optimal conditions. The intent is to create the greatest amount of electromagnetic interference that the DUT is capable of, which depends greatly on the product.

For example, for memory chips, the chips are run to read and write as quickly as they can, forcing the greatest changes in voltage and current, therefore creating the greatest electromagnetic radiation.

Once the DUT is ready, the table starts to spin while an antenna, a set distance

from the DUT slowly moves up and down, mapping the electromagnetic output at different orientations and heights. The peak output recorded must be below the guidelines for the device to pass. This test can be done at different distances, dependent on the frequency range being measured, but 3-meter and 10-meter distances are most common.

For testing immunity, the DUT is remotely operated while being subjected to large amounts of EMI. Typical values are from 3 volts per meter to 10 volts per meter from a minimum of 3 meters away. This minimum is set to ensure the DUT is in the far-field of the antenna’s radiated field. Near-field emissions

Device Under Test in Anechoic Chamber

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TECH REPORT are much more complex and difficult to accurately generate, so a highlevel far-field emission is used as the standard. A successful test occurs when the product is completely unaffected under the most extreme test scenario.

According to the FCC, every device that has electrical oscillations above 9kHz needs to be tested to verify conformance.

This includes any traces on a circuit board or even a microcontroller that oscillates above 9kHz but doesn’t have high frequency traces. Also, if a product integrates an FCC certified module, such as Bluetooth, into a larger assembly, that entire assembly may still need to be tested. Depending on if the tests pass the first time, the entire process for certification can take less than a month.

However, as there may be problems, particularly with smaller companies with less experience with EMI, the process can take considerably longer. When a device successfully passes the tests at an accredited testing facility, the facility will generate test reports and other paperwork as required to prove conformance and submit to the FCC, if necessary. The appropriate markings,

statements, and FCC ID, if applicable, are then placed in an easily accessible and viewable portion of the product.

EMC can be a confusing and intimidating topic to tackle; however, the legal, economic, and performance ramifications of compliance can be extremely significant. It is imperative that you seek further information from an authorized EMC testing company as you start your design process. Fortunately, by being aware of the issue and knowing the overall process, you have started in the right direction to making sure your products are ready for the marketplace.

Advanced Assembly was founded to help engineers assemble their prototype and lowvolume PCB orders. Based on years of experience within the printed circuit board industry, Advanced Assembly developed a proprietary system to deliver consistent, machine surface mount technology (SMT) assembly in 1-5 days. It’s our only focus. We take the hassle out of PCB assembly and make it easy, so you can spend time on other aspects of your design.

20100 E. 32nd Pkwy #225 | Aurora, CO 80011 | www.aapcb.com | 1-800-838-5650 aa-pcbassembly.com

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The Wide World of

REGULATORY

TESTING CERTIFICATIONS and

for New Product Introductions

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TECH REPORT

T

he average consumer product today has a dozen safety and certification marks, stamps, or seals that most consumers do not understand. These marks, when appropriately used, can indicate a great deal about the quality and safety of the product; they show that the product has been independently tested to verify its conformance to industry standards and regulations.

Some markings are voluntary while others, in certain cases, are mandatory.

Even if they are not mandatory, they can make the difference between acceptance and rejection when going through customs. Many times the success of a product is contingent on its certifications. However, learning which certifications are needed and how to receive them can seem overwhelming at first.

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One of the first steps during product design should be researching and working toward certification compliance. It is much simpler to implement certain criteria at the start of project than it is to try to change or retrofit the project after the fact. Once the product objective has been defined, you should begin working with the appropriate agencies to start the certification process. This article will elaborate on some of the more well known certifications, what they represent, and in what countries they are accepted.

UL One of the most widely known and respected marks is that of Underwriter Laboratories, or UL. UL was established in 1894 to find out if products being developed were safe, which remains the company’s primary goal to this day. Underwriter Laboratories has expanded into many different fields, ranging from consumer products to construction, but its focus is still safety in each of those fields. UL can certify products at the component level by giving the “Recognized Component Mark,” which indicates that the component is certified but not necessarily the end product. This is an important distinction because ULcertified PCB manufacturers often will stamp their PCBs with the “Recognized Component Mark,” but that does not mean that the overall project is UL listed. All UL markings have a number near the mark, which is searchable in the UL database.

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Before working with UL, it is advisable to review the different fields options and select the one that best fits your product.

This may change once you start the process, but it will help you understand what UL looks for and how it divides fields. After contacting UL, you will be assigned an account manager who will help you through the process. One of the first questions that a UL account manager will ask is where the product will be marketed. UL has collaborated with similar safety certifications around the world and can provide special markings to indicate that your product has been certified in the US, Canada, China, as well as a variety of countries in Europe and South America. Once the locations have been selected, the account manager will create an overview of the process and discuss what will come next. At this stage, UL provides a cost estimate and you can decide whether or not to continue in the certification process. Once you commit to the process, help is available every step of the way to make sure that your product reaches the standards set forth

by UL. You can expect to have at least one physical visit from a UL representative to view your facilities and make sure the process is being followed correctly.

Ultimately, you will receive a certification certificate and a corresponding number that end users can use to confirm that the product is legitimately UL-certified.

While UL is a nonprofit organization and a Nationally Recognized Testing Laboratory (NRTL) by OSHA,

TECH REPORT it is not a government agency, meaning certification is not mandatory. Although this testing is not mandatory in general, there are certain markets, organizations, and even municipalities that require a UL mark on selected product categories.

For example, if your product deals with hazardous energy in any way—whether it is electricity, gas, or steam—it is more likely that a UL listing will be required or strongly recommended.

CE The CE mark, or mark of the Conformité Européenne, is not an organization but simply a mark that indicates conformance to European Union (EU) standards and limits. Depending on the type of product, these standards could be for safety, environment, or even health related certifications. Perhaps the most famous directive, RoHS is an example of the many directives that fall under CE. If a product falls under one of the CE directives, it is required to meet the EU standards before it can be distributed within the European economic area, which includes the European Union and other countries, such as Turkey and Norway, that have adopted the CE mark and made it a requirement for certain imports.

Many products do not need external review but can bear the CE mark after internal processes confirm conformance.

As there is no independent review and no way to verify the legitimacy of the self-certified marks, CE cannot be

depended on as a mark of safety like UL. The products that do require external review will have a “notified body” who will independently test and decide whether or not it conforms to the standards. It should be noted that UL is one of the testing agencies allowed to perform these conformance tests. If the product passes, then an identification number will accompany the mark that can be verified online. With either the internal or external review, manufacturers and distributors need to maintain the proper paperwork indicating that due diligence was taken. This needs to be provided upon demand and, if it is found that the product does not actually qualify, the penalties can include civil and criminal charges against the company and its officers.

With the CE mark, the first steps are the simplest. Begin by searching for the different directives and note if your product fits under any of the categories.

For electronics manufacturers, it is likely that at least the RoHS 2 directive will be applicable, with the low voltage directive and the electromagnetic compatibility (EMC) directive being applicable as well.

Once all of the applicable directives have been identified, you will then need to determine if a notified body must be involved in the certification process or if you can self-certify. Even if self-certification is permitted, you can use a notified body to perform an external certification if so desired.

If self-certifying, the next step is to confirm that your product conforms to the applicable directives, and if not, make the appropriate changes. Once the product is in conformance, you will then

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document the conformance using the EC Declaration of Conformity along with any supporting technical reports. Once these steps have been completed, you can place the CE marking on the product itself or its packaging. It is in your best interests to make the marking as visible as possible in order to reduce the amount of packaging that customs will need to remove during their inspections. It is recommended to put the marking on both the final product and the packaging.

ROHS RoHS 2,the 2011 update of the original 2003 Reduction of Hazardous Substances,sets limits on the amount of certain substances in electronics. While it is merely one of many directives in the CE, its widespread effect across the globe has made it nearly a household term. RoHS is frequently referred to as the “lead-free directive” by everyone from hobbyists to manufacturers as the move to lead-free solder is the most apparent change in the certification. However, this is inaccurate because the directive covers several other hazardous materials as well. In addition to lead, RoHS limits the amount of mercury, cadmium, hexavalent chromium (to enhance corrosion protection of solder), polybrominated biphenyls (a flame retardant used in PCBs), and polybrominated diphenyl ether (another flame retardant used in PCBs). There are a multitude of exceptions to this directive, the largest

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being lead-acid batteries. Fluorescent bulbs are also exempt as mercury is required to function. All medical devices were originally exempt, but with RoHS 2, the exemption has narrowed and now only certain types of medical devices are exempt. It is a good idea to check to see if your product fits under one of these exemptions and, if it doesn’t, take care to properly conform. Breaking the threshold of any of these substances will close off practically the entire European market.

Oddly enough, if your product qualifies as an exemption, it can still bear the RoHS mark as it is technically in compliance.

When the RoHS directive was implemented, many engineers and designers simply switched to RoHS compliant equivalent parts without changing their designs. However, all of these hazardous substances were included in the PCBs and solder to improve performance, so their removal has, in most cases, reduced that performance. When planning on RoHS compliance, it is necessary to use not only RoHS-compliant parts and manufacturing processes, but also to analyze the effects of these changes in performances and temperatures.

There may be more subtle changes needed in component selection and mounting to ensure that the PCBs are still structurally and electrically robust.

WEEE The objective of the WEEE (Waste Electrical and Electronic Equipment) directive

TECH REPORT is to reduce the amount of electrical and electronic equipment waste. It also promotes the reuse, recycling and recovery of such wastes in order to limit the impact on landfills. To comply with WEEE regulations companies must participate in the Producer Compliance Scheme, which encourages producers and environment agencies as well a number of services to work together to recycle or reuse electrical equipment.

RoHS and WEEE were published at the same time and are designed to work together, however the WEEE Directive is broader and more complex.

ETL The ETL listed mark was originally a mark of the Electrical Testing Laboratories, LISTED founded in part by Thomas Edison in 1896.

Over the years, it has absorbed many different testing laboratories and is now called the Intertek Group, a worldwide testing company based out of London. Also a Nationally Recognized Testing Laboratory by OSHA, Intertek specializes in testing consumer goods and performs a wide variety of tests.

These tests are not mandatory but are performed to ensure the highest quality and safety of a product. In general, an ETL mark can be accepted as equivalent to a UL mark, but its comparative renown can be debated.

The steps to achieve ETL certification are extremely similar to UL. Upon contacting Intertek Group, you will work with an account manager who will help you through the certification process.

There are variations of the ETL mark depending on the anticipated country in which your product will be marketed.

Unlike the CE mark, which is not a guarantee of safety or quality, the ETLEU mark verifies that a product has been officially tested and deemed safe and in conformance with EU laws. The serial number associated with the mark can be verified either online or via an Intertek telephone hotline. Intertek can also be used as a notified body for the CE mark.

CANADIAN STANDARDS ASSOCIATION The Canadian Standards Association (CSA) is similar in setup to UL and Intertek Group in that it performs tests and certifies that products meet certain criteria. Originally created to define standards after World War I, CSA helps with interoperability issues among different systems. Like other certifiers, CSA has expanded in its scope beyond its original war-time specific goals and now covers a variety of fields from consumer products to industrial equipment to environmental standards.

CSA has also expanded out of Canada and is recognized in several countries in the Americas, Europe, and Asia.

While preeminently focused on safety, CSA also tests product quality and even

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electromagnetic interference. As with UL and ETL, CSA serializes its products and a product can be verified as truly CSA certified via an online form.

ELECTROMAGNETIC COMPATIBILITY CERTIFICATIONS FCC In addition to the large number of safety and health certifications, there are also several certifications specific to the emissions of electromagnetic energy.

Foremost is the Federal Communications Commission, a government organization dedicated to making wired and wireless communication available to all those living in the United States of America. As a small part of this overall goal, it organizes the wireless spectrums to reduce overlap and makes sure that unauthorized devices are not creating too much spurious RF energy in the wrong spectrum bands. To this end, the FCC requires EMC testing.

For certain items, such as cell phones, these tests and the FCC mark are required before they can hit the market. However, any item that has communication lines or traces that go above 9kHz are expected to be tested, although this is not enforced unless the product is causing electromagnetic interference issues and is reported to the FCC. The inspections for compliance are done by accredited third party vendors who will perform tests on the devices under

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a variety of different settings to make sure that maximum thresholds are not exceeded. If the device passes these tests, the device can bear the FCC mark and will be listed as compliant. If the device exceeds the maximum threshold, then you will need to have discussions with the testing agency to devise a way to reduce emissions.

Japan has a voluntary EMC testing and compliance mark called the VCCI, which is similar in intent to the US FCC mark.

While legally and technically voluntary, it has become a de facto requirement for entrance into the Japanese market.

The VCCI mark is unique in that it is required to work for both voltages and frequencies that are used in Japan.

As Japan is divided with 100VAC/50 Hz on the eastern half of Japan and 110VAC/60HZ on the western half of Japan, certification has to be completed on both inputs to receive certification.

C-TICK Australia’s and New Zealand’s equivalent to the FCC emissions standards is the C-Tick, a mandatory requirement for all products covered by Australia’s EMC regulatory arrangements. The C-Tick is only authorized for manufacturers based out of Australia or New Zealand or who use authorized agents. Testing under C-Tick is run at the standard voltages operating in Australia and New Zealand, namely 230VAC/50HZ.

TECH REPORT BSMI Taiwan’s Bureau of Standards, Metrology and Inspection sets the EMC standards for Taiwan, which are similar to FCC’s, in part due to the similar voltages of the USA and Taiwan. Taiwan accepts the results of testing facilities outside of the country, making it considerably easier to perform the testing. Due to Taiwan’s rising prominence in the high tech industry, this mark is becoming more prevalent and necessary.

KC The Korea Certification (KC) mark was changed as of January 2011 from the Korea Communications Commission mark. The requirements are very similar to those in Europe, but testing is performed at 220VAC/60Hz in

accordance with South Korea’s electrical infrastructure. Previously, the KC or KCC marks required in-country testing, but it has expanded to allow testing centers outside of Korea to certify products.

The above mentioned certifications are encountered mostly frequently when introducing new electronic products to the market. However, this is a small sample of the very large world of regulatory testing and certifications.

While there is a great deal of overlap between many of the certifications, it is still imperative to anticipate the market needs of your product. Whether it’s for the Americas, Europe, Australia, or Asia, it is important to design and certify for each specific market. Doing so will save time and money, and prevent many headaches associated with trying to retroactively incorporate the standards. Finally, being able to easily and legally distribute your end product worldwide could make the difference between success and failure of your product and your company.

Advanced Assembly was founded to help engineers assemble their prototype and lowvolume PCB orders. Based on years of experience within the printed circuit board industry, Advanced Assembly developed a proprietary system to deliver consistent, machine surface mount technology (SMT) assembly in 1-5 days. It’s our only focus. We take the hassle out of PCB assembly and make it easy, so you can spend time on other aspects of your design.

20100 E. 32nd Pkwy #225 | Aurora, CO 80011 | aa-pcbassembly.com www.aapcb.com | 1-800-838-5650

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CLICK HERE

CLICK HERE

The Future of

Wireless Cypress’ PSoC Products Enable Next Generation IoT Applications

T

28

he landscape of the wireless

chip that integrates a Bluetooth low

industry is dramatically

energy (BLE) radio—tailor-made for

changing. The rise of the

the development of IoT applications.

Internet of Things has spurred tech

The PSoC 4 BLE solution features

companies to begin developing low-

the PSoC architecture’s hallmark

power, yet robust devices that will

adaptability and customization,

support the increasing needs of the

making it the perfect solution for a

world’s biggest network. For Cypress

rapidly changing industry. EEWeb

Semiconductor, a diverse wireless

spoke with John Weil, VP of Marketing

portfolio is nothing new; the company

for the Programmable Systems

has offered RF products before the

Division at Cypress, about how the

IoT began to take shape. Recently,

company adapts to market demands

Cypress released a new version of its

and how their PSoC will enable the

PSoC® 4 programmable system-on-

future wireless markets.

INDUSTRY INTERVIEW

Our PSoC programmable system-on-chip integrates a microcontroller core, a programmable digital fabric, and a programmable analog subsystem —all into a unique, customizable, one-chip embedded solution.

Interview with John Weil – VP of Marketing for the Programmable Systems Division at Cypress Semiconductor Corp.

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How do you identify where Cypress’ PSoC products need to be in terms of what the market trends are dictating?

Cypress’ PSoC® programmable systemon-chip line allows customers to adapt to new market trends. In a way, with PSoC, we are providing insurance to customers and are letting them design products that solve a problem that wasn’t originally thought of. It’s like a Swiss Army Knife; it solves a lot of problems without it being designed for any one particular problem.

That said, we spend a lot of time with our customer base, so we work closely with consumer and industrial customers gathering requirements for product definition. The key here is looking across those industries and seeing if you can connect dots along the way— maybe the industrial companies have thought of something that consumer companies are already working on.

What are some of Cypress’ wireless solutions for IoT development?

Cypress has had a wireless portfolio for a while, preceding the rise of the Internet of Things. The thing that has been missing in this industry for a long time is a good, standardized RF connection that provides a low-power interface. With this in mind, Cypress has invested in the Bluetooth low energy (BLE) platform. We believe it provides ubiquitous connectivity to all different types of applications. We released our first Bluetooth product, PSoC 4 BLE, in the fall of 2014, and we have another one coming to market at the end of this quarter. We also

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have a module-based product coming out later. We are building a strong portfolio of BLE products very quickly.

What is unique or different about Cypress’ BLE product portfolio?

The differentiation for our BLE portfolio comes from the programmability of our PSoC heritage. Most of our customers are still defining exactly what they need right now to build their next IoT device. We see customers building everything from internet-connected coffee mugs to light bulbs to personal healthcare devices.

When you look at all of these devices, the interfaces required are quite varied. If you look at the BLE providers in the market today, most are expecting another microcontroller in the solution. However, with a fixed-function microcontroller, if the customer goes with Vendor A and the marketing group tells the engineering group they need some additional features, then Vendor A needs to have a BLE solution that caters to those needs or else the whole product is stuck.

We integrated a BLE radio into our PSoC family—specifically our PSoC 4 family— so users can reconfigure our analog and digital fabric in the chip to make it emulate and handle the functions of a wide variety of microcontrollers.

If the customer wants to change the number of UARTs, it requires just a change in the schematic configuration tool, and we then re-program the fabric of PSoC to create extra UARTs. This allows the customer to have one chip that provides hundreds of solutions.

INDUSTRY INTERVIEW Could you give us a brief definition of PSoC and how it is different from other microcontrollers?

Our PSoC programmable system-onchip integrates a microcontroller core, a programmable digital fabric, and a programmable analog subsystem – all into a unique, customizable, one-chip embedded solution.

PSoC® 4 BLE THE INTERNET OF THINGS ON A CHIP

Our latest generation is called PSoC 4, which is an ARM Cortex-M0-based SoC. It has a complex programmable logic device (CPLD) fabric embedded in it. Each one of these CPLD blocks has an arithmetic logic unit in it and two different CPLD blocks, which allows the user to do combinational or registered logic. These blocks can be connected together to create more complex logic; you can write a few lines of Verilog to create the logic, just like an FPGA, or you can design statemachines. In a way, each digital block represents a pico-processor that can be used to accelerate and perform tasks.

Another key ingredient of PSoC is the programmable analog subsystem. We treat our chip as much as an analog chip as it is a digital chip. For example, every pad on PSoC 4 is an analog pad with digital capability. This means the pad can be turned on with a signal connected to it, and the signal can be routed into a pin on the chip and out through another pin. This feature cannot be found in any other microcontroller on the market. The various blocks that make up the analog subsystem include standard off-the-shelf components like

The PSoC® 4 is like a Swiss Army Knife; it solves a lot of problems without it being designed for any one particular problem.

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opamps, analog muxes, comparators, analog-to-digital converters, etc. that can perform a multitude of analog signal conditioning tasks.

What has the customer reception been like for the PSoC 4 BLE solution in the IoT and wearables markets?

It has been remarkable. There is tremendous growth potential in this market. I lived through the ZigBee days and have promoted many different wireless technologies and even I underestimated what BLE was capable of.

We sampled some of our first customers in late October; and one had a product they were working on already with a competitor and found there were some aspects of it that were not possible because the BLE solution did not have the analog they needed. They were able to swap out that chip with one of Cypress’ solutions to solve their analog problem, so that they could measure temperature, pressure, and mineral count in water—all with our single chip. They were then able to take that product to market in 30 days.

Another example of our customers moving quickly is with personal healthcare devices. With wearable technology monitoring health vitals, we can now garner another layer of information from things you interact with in our everyday lives. Some of our customers in this sphere are moving their products to market in just a few months— which is remarkably fast. That speed of product development lends itself nicely to PSoC. Our customers’ marketers are

32

coming to their engineers and saying they need certain capabilities in a matter of months, and they don’t know how to deliver a solution with what they have.

They can build a PSoC solution, certify and build their design, get their RF working, and are able to make any last minute adjustments without having to swap out the part. That speed to market is exactly why PSoC 4 BLE is taking off.

Could you talk about your CapSense® technology?

I tell people that CapSense is a little bit like Kleenex—we invented it and everyone uses the word CapSense to refer to capacitive sensing. A lot of our competitors have a similar technology available now, but when you look at their technology, there is really no comparison to ours. For Cypress, capacitive sensing is an analog concept.

The reason why all 36 pads on our PSoC 4 are analog, is because all 36 I/O are CapSense measurement engines. We are able to measure very small amounts of capacitance changes, which allows us to do some very interesting things.

For example, CapSense technology is integrated into our PSoC 4 BLE products. They can control when the radio goes on and off based on how the user is interacting with the touch-sensing controls of the end product, which really helps minimize power consumption and prolong battery life. There are also some unique non-touch applications, such as liquid-level sensing.

INDUSTRY INTERVIEW If you think about it, all of the things that surround you at any given time will have a small capacitance change relative to some copper electrode. I tell our customers that they can sense their world with our capacitive sensing blocks.

Take countertop IoT devices like coffee machines for example: the user can now plug personal preferences into specific apps developed by the appliance maker.

These preferences go over a BLE link when the user walks into the kitchen and the coffee machine senses their smartphone and cues up their favorite drink. Our capacitive sensing technology can drive the touchscreen on the coffee machine and it can also report how much water is in the machine using mutual capacitance.

What is the vision you have for Cypress and enabling these next generation IoT products?

Over the last decade, we have spent a lot of time with customers helping them build cool user interfaces. PSoC really came to fame handling the touch-sensing in the original iPod click wheel. We have gone on to produce some really great touchscreens for flagship cellphones and are now moving on to the wearables market.

We have now added an RF link to allow our touch and human-machine interface capability to communicate wirelessly with other objects. This could be everything from light switches to gesture-recognition door handles—all with our CapSense technology. We are working with our customers to help them invent new ways to connect their end users’ world with an RF link.

The differentiation for our BLE portfolio comes from the programmability of our PSoC heritage.

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By Alex Lidow, CEO Efficient Power Conversion (EPC)

34

TECH SERIES

Wi GaN:

Radiated EMI Comparison Between Class E and ZVS Class D Amplifiers in 6.78 MHz Wireless Power Transfer

In the previous installment of Wi GaN, we presented the superior performance 速 ofCLICK eGaNHERE FETs employed in Class E and ZVS Class D amplifiers driving a wide range A4WP class 3 compliant load. In this article, we present an analysis of the radiated EMI comparison between the same amplifiers. EMI is a subject that needs to be addressed in any power electronic design, and wireless power is no exception. Wireless power systems operating at 6.78 MHz are classified as

intentional radiators and are therefore subject ISM band regulations [1, 2].

If the spectral content of the energy introduced into the radiator falls outside the transmission bandwidth limits, it will radiate as electromagnetic interference (EMI) [3]. This radiated interference is difficult to reduce because traditional power circuit EMI abatement techniques [4, 5, & 6] will have a significant impact on the performance of the coil and matching circuits.

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The radiated EMI limits, spanning the frequency range from 6 MHz through 1 GHz, present the greatest challenge to wireless power products falling under class B regulations, which have the lowest limits. The intentional ISM band radiator standards restrict the frequency bandwidth of the radiated energy, but essentially allow unlimited radiated power, with a few exceptions [7], in the frequencies targeted for wireless power.

Radiated EMI Overview A radiated EMI system is comprised of five basic components: a source, a transmission path, a radiator (antenna), a receiver, which is a defined as a circuit that can be corrupted, and EMI standards, which set the limits for radiated electromagnetic energy [1, 2, & 3]. These five components are shown in Figure 1. Filtering is not considered a component of an EMI system but rather a means to limit the magnitude of EMI radiated within a specific frequency range.

The Radiator in Wireless Power Systems In a wireless power system the source coil becomes the main radiator due to its size, construction and function. The source coil is simply a large inductor with high impedance.

Current is injected into the coil by the amplifier, and assisted by series-tuning the coil with a capacitor to yield low impedance path as shown in Figure 2. The current in the coil generates an H-field that will radiate; therefore any frequency present in the current will also be present in the H-field. Most of those frequencies will be unwanted and must be prevented from being present in the current prior to entering the source coil. Since there is current present in the source coil inductance, it will have a corresponding voltage (V2) associated with it. Furthermore, it is not possible to ground reference the entire coil, and hence the coil will also serve as an E-field radiator as shown in Figure 2.

Figure 1: Radiated EMI system Overview.

Figure 1: Radiated EMI system Overview.

The receiver should not be confused with the specific receiver for EMI testing, but rather any receiver (circuit) that can be corrupted by unwanted frequencies and electromagnetic energy. The absence of any one of the EMI system components results in no radiated EMI, however, given the presence of the radiated EMI standards and associated receivers, the EMI problem falls solely on the product itself.

36

Figure 2: The wireless power transfer coil as EMI radiator.

TECH SERIES Voltage (V1) generated by the amplifier couples directly through the series-tuning capacitor, which provides a low impedance path from the output of the amplifier to the coil and adds to the voltage (V2) generated by the coil current.

This will exacerbate the radiated EMI problem due to the increase in unwanted magnitude and frequency content of the E-field and which is considered the most difficult to abate.

Figure 3: SchemaCc of the Class E (leF) and ZVS Class D (right) amplifiers simulated Figure 3: Schematic of the Class E (left) and ZVS Class D (right) amplifiers simulated

Two topologies, the class E and ZVS class D shown in Figure 3, will be analyzed in an LTspice [8] simulation, using the same source coil and operating conditions, to determine the differences in radiated EMI generation. Both amplifiers will be realized using applicable eGaN FETs [9, 10, & 11].

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Figure 4: Hi Res V(coil)

420V

I(Lcoil)

1.2A

350V

1.0A

280V

0.8A

210V

0.6A

140V

0.4A

70V

0.2A

0V

0.0A

-70V

-0.2A

-140V

-0.4A

-210V

-0.6A

-280V

-0.8A

-350V 0ns

60ns

120ns

180ns

240ns

300ns

360ns

420ns

480ns

540ns

-1.0A

Figure 4: Time domain coil current and voltage driven by the class E amplifier.

Class E Amplifier Radiated EMI Analysis A single-ended class E amplifier driving an equivalent circuit A4WP class 3-compliant source coil set to deliver 14W into the load was analyzed first. The time domain current in the coil and voltage across the coil is shown in Figure 4.

A Fourier analysis on the time domain waveforms from 1 MHz through 1 GHz and shown in Figure 5 reveals that both waveforms have significant frequency content. As predicted, the current waveform frequency content will be fully

Figure 5: Hi Res

2·∙f0

60dB

20dB 0dB -20dB

V(coil)

f0

2·∙f0

0dB

4·∙f0

40dB

present on the voltage waveform, with additional frequencies and corresponding magnitudes from the amplifier. High-magnitudes of even-order harmonics on both the current and voltage waveforms are present. These harmonics are considered the most difficult to reduce and bring within acceptable limits. The difficulty is that even-order harmonics impact the fundamental frequency asymmetrically and can cause power fluctuations. Even-order harmonics are present in a class E amplifier due to the dual resonant frequency structure of the topology.

4·∙f0

-20dB

-40dB

I(Lcoil)

f0

-60dB

-40dB -80dB

-60dB -80dB

-100dB

-100dB

Voltage

-120dB -140dB

10MHz

100MHz

1GHz

Figure 5: Frequency domain coil current and voltage driven by the class E amplifier.

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Current

-120dB

-140dB

10MHz

100MHz

1GHz

Figure 6: Hi Res

TECH SERIES

V(coil)

420V

I(Lcoil)

1.2A

350V

1.0A

280V

0.8A

210V

0.6A

140V

0.4A

70V

0.2A

0V

0.0A

-70V

-0.2A

-140V

-0.4A

-210V

-0.6A

-280V

-0.8A

-350V

-1.0A

-420V 0ns

60ns

120ns

180ns

240ns

300ns

360ns

420ns

480ns

540ns

-1.2A

Figure 6: Time domain coil current and voltage driven by the ZVS class D amplifier.

ZVS Class D Amplifier Radiated EMI Analysis A single-ended ZVS class D amplifier is then analyzed in the same manner and with the same operating conditions as the class E amplifier.

The time domain results for both the source coil current and voltage are shown in Figure 6.

The current and voltage waveforms appear to be very clean with the exception of the voltage waveform during the amplifier output transition.

This is due to the low impedance of the matching capacitor and amplifier output together with the high impedance of the source coil that allows a

portion of the output voltage transition of the amplifier to appear on the source coil voltage waveform.

A Fourier analysis on the time domain waveforms from 1 MHz through 1 GHz and shown in Figure 7, reveals that both waveforms also have significant frequency content.

Figure 7: Hias predicted, Res the current waveform Again,

2·∙f0

60dB

0dB -20dB

V(coil)

f0

2·∙f0

0dB

4·∙f0

40dB 20dB

frequency content will be fully present on the voltage waveform with additional frequencies

4·∙f0

-20dB

-40dB

I(Lcoil)

f0

-60dB

-40dB -80dB

-60dB -100dB

-80dB -100dB

Voltage

-120dB -140dB

10MHz

-120dB

-140dB

100MHz

1GHz

Current 10MHz

100MHz

1GHz

Figure 7: Frequency domain coil current and voltage driven by the ZVS class D amplifier.

39

and corresponding magnitudes. In the case of the ZVS class D amplifier, the absence of evenorder harmonics in both current and voltage is notable. This is due to the symmetrical nature of the amplifier and was further found to be independent of variations in duty cycle that may arise from propagation mismatch due to various components in the circuit.

The radiated EMI content in the frequency range from 50 MHz through 300 MHz is higher than the class E amplifier, circled in Figure 7, which is due to the rapid voltage transition of the amplifier output. Since this frequency range is significantly higher than the operating frequency, it should not pose too much of a challenge to reduce for radiated EMI compliance. However, caution should be exercised with EMI mitigation techniques as they can affect the tuning of the source coil.

40

Summary In this column, both class E and ZVS class D amplifier topologies using eGaN FETs were evaluated for radiated EMI generation. It was shown that the class E amplifier fundamentally generates high magnitudes of even-order harmonics, which are very difficult to remove, particularly if the frequencies are close to the fundamental. The ZVS class D amplifier however does not generate even-order harmonics, despite generating higher magnitudes at higher frequencies which are easier to remove, making it a cleaner choice with respect to radiated EMI. click eGaNhere FETs also make for better devices, with

respect to EMI, when used in either amplifier topology due to their lower input capacitance (CISS), output capacitance (COSS), excellent miller ratio, and lack of reverser recovery (QRR), which combined leads to a significant reduction in EMI generation of the amplifier. The lower CISS, typically four times lower than comparable on-state resistance (RDS(on)) MOSFETs, results in a lower gate current and hence lower EMI source magnitude. The lower Miller ratio establishes a higher impedance path for EMI propagation from the gate to the drain and in combination with the lower CISS results in lower gate circuit generated EMI from corrupting the output of the amplifier. The lower COSS, typically two times lower than comparable on-state resistance (RDS(on)) MOSFETs, is beneficial when either of the amplifiers is driving off-ideal impedance loads where the smaller COSS reduces EMI generated energy.

MOSFETs also have QRR which plays a significant role in the ZVS Class D amplifier because the output voltage switching transition time (Δtvt) is typically much shorter than the reverse recovery time (tRR), thereby adding additional EMI energy to the amplifier output. Combining all these factors results in higher frequency content EMI generated by eGaN FETs than MOSFETs making EMI abatement techniques easier to implement.

TECH SERIES

References [1] FCC Code of Federal Regulations Title 47, Vol. 1, Part 18 B (Industrial, Scientific, and Medical Equipment), 1998 [2] Electromagnetic Compatibility (EMC), European Directive (2004/108/EC) [3] European Norm. EN55011 Group 2 Class B [4] “A Solution for Peak EMI Reduction with Spread Spectrum Clock Generators”, On-Semi Application Note AND9015, July 2011.

[5] “Design for EMI,” Intel Application Note AP-589, February 1999.

[6] M. J. Schneider, “Design Considerations to Reduce Conducted and Radiated EMI,” College of Technology Masters Theses, Paper 4, 2010, http://docs.lib.purdue.edu/ techmasters/4 [7] J. Roman, R. Paxman, N. Zou, Y. Nakagawa, J. Cho, ”Inductive Wireless Power Regulations,” Wireless Power Summit, Berkeley CA, U.S.A., November 2014.

[8] www.linear.com/ltspice [9] A. Lidow, “Wi GaN: eGaN® FETs Yield High Efficiency in Wireless Energy Transfer,” EEWeb: Wireless & RF Magazine, pp. 13–17, November 2014.

[10] EPC2012 datasheet, http://epc-co.com/ epc/Products/eGaNFETs/EPC2012.aspx [11] EPC8009 datasheet, http://epc-co.com/ epc/Products/eGaNFETs/EPC8009.aspx

eGaN® FET is a registered trademark of Efficient Power Conversion Corporation.

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