An mm-Wave Synthesizer With Robust Locking Reference-Sampling PLL and Wide-Range Injection-Locked VCO

In this article, a two-stage millimeter (mm)-wave frequency synthesizer with low in-band noise and robust locking reference-sampling techniques is presented. Using a two-stage scheme allows separately dealing with the low phase noise (PN) frequency synthesis in the first stage and the mm-wave frequency multiplication in the second stage, achieving the best overall power efficiency. In the first stage, a voltage domain reference-sampling phase detector (RSPD)-locked loop (RSPLL) is adopted to achieve both low PN and robust locking without additional frequency locking loop. A reference reshaping buffer is implemented to improve the phase detector gain and in-band PN. The reference rising/falling time is programmable to achieve optimal RSPLL performance even under external disturbances. The second stage employs an injection-locked voltage-controlled oscillator (ILVCO) for 4× frequency multiplication. A low-power digital frequency tracking loop (FTL) detecting actual frequency errors is implemented in order to achieve wide operation range for the ILVCO while using a high Q tank with low power. The prototype synthesizer was fabricated in a 45-nm partially depleted silicon on insulator (PDSOI) CMOS technology. The first stage 9-GHz RSPLL achieves 144-fs integrated jitter with 7.2-mW power consumption, achieving a figure of merit (FoM) of -248 dB and the overall mm-wave synthesizer achieves 251-fs integrated jitter with 20.6-mW power consumption at 35.84 GHz, achieving an FoM of -238.9 dB.