DIRECT CONVERSION RECEIVER

摘要

A homodyne receiver according to the present invention includes a signal input and first and second mixers coupled to the signal input. A local oscillator provides a reference signal at the frequency of modulation of the input signal. The reference signal output by the local oscillator is passed through a switchable phase change element, the output of which is coupled directly to the first mixer and indirectly to the second mixer through a second phase change element. The switchable phase change element changes the phase of an input signal by a predetermined phase based on the state of a control input, such that the output of the phase change element in one state is pi radians out of phase with the output of the phase change element in the other state. The second phase change element changes the phase of an input signal by pi /2 radians. The outputs of the mixers are coupled to a pair of switchable inverters and low pass filters. Switching of the switchable phase change element and the switchable inverters is controlled by a switching oscillator.