A positive-peak detector with adaptive micro-current compensator for wideband VCOs

摘要

A precise positive-peak detector with adaptive micro-current compensator is proposed to trace the tank amplitude VT of wideband VCOs. The compensator includes three micro-current Imicro branches controlled by automatic frequency calibration (AFC). A decoding circuit is connected between the AFC and the compensator. If oscillation frequency of VCO increases, by use of the decoding circuit, the branch with smaller Imicro would be adaptively chosen for precisely tracing the VT. In TSMC 0.18μm CMOS technology, when the proposed positive-peak detector is used for a VCO with output frequency from 1.52GHz to 3.2GHz, the maximum detection error is 80mV under different corners and temperature from −40°C to 80°C.