This paper present a 20-GHz differential push-push voltage controlled oscillator (VCO) for 60-GHz frequency synthesizer. The 20-GHz VCO consists of a 10-GHz in-phase injection-coupled QVCO (IPIC-QVCO) with tail-filter and a differential output push-push doubler for 20-GHz output. The VCO fabricated in 65-nm CMOS technology, it achieves tuning range of 3 GHz from 17.5 GHz to 20.4 GHz with a phase noise of -113.8 dBc/Hz at 1 MHz offset. The core oscillator consumes up to 71 mW power and a FoM of -180.2 dBc/Hz is achieved.

A subharmonic injection-locked oscillator (ILO) MMIC chain is proposed for the local oscillators and synthesizers used at millimeter-wave frequencies. A fabricated, primary 11-GHz-band injection-locked oscillator MMIC for the first stage ILO in the ILO-chain MMIC, achieves a wide subharmonic-injection-locking range at the subharmonic factors, 1/n (n=1, 2, 3, ), of 1/1, 1/2 and 1/3. The ILO MMIC abilities for synthesizer applications were confirmed with an injection-locking time of only 100-200 nsec, which is less than 1/100 that of PLL oscillators, and also with free-running oscillation performance and a wide injection locking range within a temperature range of -30 and 80.