A high-sensitivity battery-less wake-up receiver for 915 MHz ISM band applications

A high-sensitivity fully passive 902-928MHz ISM band wake-up radio (WuRx) receiver for implantable biomedical devices is presented. The WuRx does not have an external power source and harvests the entire energy from the radio-frequency (RF) signal received at the antenna. A high-efficiency differential RF-to-DC converter rectifies the input RF signal and supplies the circuit blocks including a low-power comparator and reference generators; and at the same time retrieves the envelope of the On-Off Keying (OOK) wake-up signal. To enhance the power conversion efficiency (PCE) of the proposed rectifier when the input power is low, appropriate gate-drive voltages for each stage of the rectifier are generated using a chain of auxiliary cells. The WuRx is designed and implemented in 0.13 μm CMOS and achieves a sensitivity of -43 dBm for a 100 kbps wake-up signal.