FM demodulator using injection locked oscillator having tuning feedback and linearizing feedback

摘要

A demodulator circuit (100) and method for producing a demodulated signal VOUT from an input signal VIN. A frequency detection circuit (101) produces a quadrature signal VQUAD which is compared to the input signal VIN to produce a detected output signal. The phase and frequency of the quadrature signal VQUAD are responsive to a control signal ICONTROL. The demodulator circuit (100) has an output terminal (114) which provides the demodulated signal VOUT. Nonlinearity in the demodulated output signal VOUT in relation to a modulating signal is reduced by a linearizing feedback circuit (102). Automatic tuning is provided by a tuning feedback circuit (103). The output signals produced at the respective output terminals (114) and (113) of the linearizing feedback circuit (102) and tuning feedback circuit (103) are summed to produce the control current ICONTROL.