A Spur-Reduced Power-Efficient Fully Differential VCO-based Operational Transconductance Amplifier

In this paper a spur-reduced fully differential VCO-based operational transconductance amplifier (VCO-OTA) is presented. This work extends a state-of-the-art (SOTA) implementation, where a combination of a phase-frequency detector (PFD) and a charge pump (CP) is utilized. The architecture is enhanced by splitting the CP into three CPs while the total current remains the same. Compared to the SOTA architecture our implementation features significantly reduced ripples, i.e., a spur reduction of 13.9 dB, while shifting harmonics to three times higher frequencies due to the higher interleaved clock of the output stage. With a combination of the three CP blocks into a single unit, these improvements are achieved without spending significantly more power or area as compared to the SOTA VCO-OTA.