CMOS 120 GHz phase-locked loops based on two different VCO topologies

This work describes the development and comparison of two phase-locked loops (PLLs) based on a 65-nm CMOS technology. The PLLs incorporate two different topologies for the output voltage-controlled oscillator (VCO): LC cross-coupled and differential Colpitts. The measured locking ranges of the LC cross-coupled VCO-based phase-locked loop (PLL1) and the Colpitts VCO-based phase-locked loop (PLL2) are 119.84-122.61 GHz and 126.53-129.29 GHz, respectively. Th e output powers of PLL1 and PLL2 are -8.6 dBm and -10.5 dBm with DC power consumptions of 127.3 mW and 142.8 mW, respectively. The measured phase noise of PLL1 is -59.2 at 10 kHz offset and -104.5 at 10 MHz offset, and the phase noise of PLL2 is -60.9 dBc/Hz at 10 kHz offset and -104.4 dBc/Hz at 10 MHz offset. The chip sizes are 1,080 μm × 760 μm (PLL1) and 1,100 μm × 800 μm (PLL2), including the probing pads.