Millimeter-wave HBT MMIC synthesizers using subharmonically injection-locked oscillators

A subharmonically injection-locked MMIC harmonic VCO for use as a synthesized local oscillator in the 60 GHz band has been experimentally investigated. The designs using HBT MMICs are based on the use of 2nd subharmonic injection locking of the harmonic VCOs to upconvert to millimeter-wave frequency and broaden the locking range. The use of the 4th harmonic signal from the VCOs allows a factor of eight increase in the locking range. The transmission type injection-locked MMIC VCO with the refractive type load circuit increases not only the locking range, but also the high-order harmonic output power in the locked VCO output.