Radios
ASSIST is also building Bluetooth-compatible radios that can communicate with standard BL radios but with a significant reduction in power consumption.
Three major techniques are used to reduce the total power consumption of only 0.5 mW, which is an 8X reduction over a state of the art COTs BLE radio: 1) the TX only transmits in one advertising channel packet with open-loop direct modulation after every frequency calibration cycle; 2) a successive approximation register (SAR)-assisted frequency locked loop (FLL) is implemented by utilizing a RF/4 frequency ring oscillator (RO) with 4X phases; and 3) a switch-capacitor digital PA (SCDPA) optimized for high efficiency below -5dBm.