Self-oscillating mixer circuits, and FMCW radar

A frequency-modulated continuous-wave radar comprising an antenna, a sweep waveform generator for producing a modulating signal, and a circuit for producing an IF signal, said circuit comprising:

• a. a self-oscillating mixer for producing an RF signal, modulating the RF signal in response to the modulating signal, and mixing the modulated RF signal with a reflected return of said modulated signal, said mixer including:
• (1) an input electrically connected to the sweep waveform generator for receiving the modulating signal;
• (2) an RF line electrically connected to the antenna for carrying the modulated RF signal and the reflected return;
• (3) an output for providing an IF signal resulting from said mixing;
• and
• b. cancellation means for combining the IF signal with the modulating signal to cancel from the IF signal a modulation corresponding to that of the modulated RF signal, said cancellation means including a first input coupled to the output of the mixer, a second input electrically connected to the sweep waveform generator for receiving the modulating signal, and an output for producing a demodulated IF signal.