A subharmonic self-oscillating mixer using substrate integrated waveguide cavity for millimeter-wave application

A low-cost, compact, subharmonic self-oscillating mixer integrated with antenna is presented and demonstrated at 30GHz. This novel configuration makes use of substrate integrated waveguide (SIW) cavity as a resonator in the feedback loop to stabilize the fundamental oscillating frequency. This allows the possibility of building a complete planar receiver, with improved phase noise, as an integrated front-end for millimeter wave systems such as radar and wireless sensor network. It is also an attractive structure for MMIC design. A convenient method free from FET amplifier design is proposed in the work for this kind of self-oscillating mixer, which can also be applied in SIW oscillator design. The circuit, implemented as a down-converter, exhibits an average conversion loss of 8.6dB, and an IF phase noise of -86dBc/Hz at 100-kHz offset. The effects of DC variation on the oscillating frequency and the output P_1dB gain compression are measured and demonstrated.