A 140-GHz 9-mW Self-Calibrating Quadrature Generator

A quadrature generator based on RC-CR circuits maintains a 90° phase separation independent of input frequency, while its amplitude imbalance is sensed by a novel amplitude detector and automatically corrected by an analog feedback loop. Implemented in 28-nm CMOS technology, the prototype draws 9 mW of power, and achieves 0.56-dB amplitude error and a ±1.3° phase error after de-embedding the systematic offset.