AMASS PLL: An Active-Mixer-Adopted Sub-Sampling PLL Achieving an FOM of −255.5DB and a Reference Spur of −66.6DBC

An active-mixer-adopted sub-sampling (AMASS) PLL is presented that replaces the passive-mixer-like sample-and-hold switches and charge-pump of a sub-sampling PLL with an active-mixer and gm-cell, which reduces spurious content by 20dB while enabling sub-mW power consumption. Fabricated in 65nm, the AMASS PLL achieves an RMS jitter of 174fs from 10kHz to 100MHz with a spur of -66.6 dBc, all at a power of 0.93mW, for an FOM of -255.5dB.