Low-power MEMS-based CMOS Transceivers

An ISM 915-MHz FSK transceiver for low power internet-of-things (IoT) applications is presented in this paper. The system supports a shared antenna interface of FSK-matched filter for TRX and a matching network for the FSK RX. To consume less power, the transmitter employs an adaptive fast switching technique for FSK modulator, and uses a high-Q MEMS resonator to get frequency stability. In addition, for better interference filtering, the MEMS-based modulator is shared to provide LO in FSK RX as it owns inherent side-lobe suppression. Fabricated in 65-nm CMOS process, the TX generates FSK signals of -8.2dBm output power at ISM-915 MHz and the data rate is up to 10Mb/s. At 1 MHz offset, the measured phase noise is -139.4dBc/Hz and -138.7dBc/Hz at 911.9 MHz and 923.1 MHz, respectively. By sharing the modulator, the RX exhibits -30.7dB in-band SIR, -72dBm sensitivity at BER of 10-3. The TX and FSK RX consume 753 μW@10 Mb/s and 700.5 μW@10 Mb/s, leading to the energy efficiency of 75. 3pJ/b and 70 pJ/b, respectively.