An RF Based Analog Linear Demodulator

Quadrature homodyne receivers have been used extensively for wireless life sign monitoring applications. In this letter, a new single mixer receiver architecture is proposed, that uses a phase tuning method to reach optimum demodulation point, and remove the dc offset associated with homodyne receivers. This method significantly simplifies the receiver architecture, and eliminates the demodulation step of processing baseband data. Experimental results obtained with this system demonstrate that physiological signals have been obtained without distortion, and with estimated heart rate accuracy of 99% for a stationary subject.