A UWB-Based Sensor-to-Time Transmitter for R F-Powered Sensing Applications
Abstract: An ultrawideband (UWB)-based sensor-to-time transmitter consisting of a remote control ( ) time-constant interface and an ultralow-power pulse generator is presented. The sensing information is directly extracted and transmitted in the time domain, exploiting UWB pulses with a high time-domain resolution. This approach eliminates the need for an analog-to-digital converter and baseband blocks of sensor tags; meanwhile, it reduces the number of bits to be transmitted for energy saving. The sensor interface measures the discharging time of the time constant proportional to the sensor variation. The UWB pulses are triggered with intervals of the discharging time, without any digitizing or modulations. The circuit prototype is implemented in the standard 0.18CMOS process. Resistance measurement results show that the proposed system exhibits an effective number of resolution bits (ENOB) of 7.7 bits with an average relative error of 0.42% in the range of 200–1500 . The overall energy consumption of conversion and transmission per sample is measured to be 0.58 nJ with a 1.27-Vp-p pulse amplitude, which is favorable to radio-frequencypowered wireless sensing applications.