Ultra Low Power Transceiver for Wireless Patient Vital Sign Monitoring

An ultra low power analog transceiver front end module for an FSK based fully differential 2.4 GHz transceiver in 0.18 mum CMOS technology is described in this paper. The transceiver consists of a programmable class C power amplifier, passive ring mixer and a matching circuit which provides the required load for the PA as well as matches the mixer input impedance to the antenna similar to that described in [1]. A new baseband module produces a pulse train corresponding to the transmitted information. Both the PA and the passive mixer are driven by a 2.4 GHz VCO similar to that described in [2], modified for low voltage operation. The simulated overall power consumption of the receiver chain is 150 uW and the overall PA efficiency is 36% for 240 muW transmitted power. The simulated phase noise of the 2.4 GHz VCO is -90dBc/Hz at 1 MHz offset and the power consumption of the VCO is 103 muW. The output frequency of the VCO can be varied by means of a control voltage to generate FSK modulation.