A 284-µW 1.85-GHz 20-phase oscillator using transfer gate phase couplers

We propose a transfer gate phase coupler for a low-power multi-phase oscillator (MPOSC). The phase coupler is an nMOS transfer gate, which does not waste charge to the ground and thus achieves low power. The proposed MPOSC can set the number of outputs to an arbitrary number. The test circuit in a 180-nm process and a 65-nm process exhibits 20 phases, including 90° different angles. In a 65-nm process, the measured peak DNL and 3s period jitter are, respectively, less than ±1.2° and 5.82 ps. The minimum I/Q angle error is 0.019°. The power is 284 µW at 1.85 GHz.