A low-power CMOS BFSK transceiver for health monitoring systems

A CMOS low-power transceiver for implantable and external health monitoring devices operating in the MICS band is presented. The LNA core has an integrated mixer in a folded configuration to reuse the bias current, allowing high linearity with a low power supply levels. The baseband strip consists of a pseudo differential MOS-C band-pass filter achieving demodulation of 150kHz-offset BFSK signals. An all digital frequency-locked loop is used for LO generation in the RX mode and for driving a class AB power amplifier in the TX mode. The MICS transceiver is designed and fabricated in a 0.18μm 1-poly, 6-metal CMOS process. The sensitivities of -70dBm and -98dBm were achieved with NF of 40dB and 11dB at the data rate of 100kb/s while consuming only 600μW and 1.5mW at 1.2V and 1.8V, respectively. The BERs are less than 10^-3 at the input powers of -70dBm at 1.2V and -98dBm at 1.8V at the data rate of 100kb/s. Finally, the output power of the transmitter is 0dBm for a power consumption of 1.8mW.