A △∑-Modulator-Less Digitally-Controlled Oscillator using Fractional Capacitors for Cellular Transmitter

摘要

A △∑-modulator (DSM)-less digitally controlled oscillator (DCO) based on 65-nm CMOS technology, incorporating a fractional-capacitor and ground-shield techniques, for a GSM/EDGE transmitter was developed. The fractional-capacitor and ground-shield techniques, respectively, achieve high frequency resolution (0.6 kHz) without a conventional DSM and small differential non linearity (DNL) of DCO gains (0.12 LSB). A transmitter using the DCO exhibits both low phase error (0.9°) and in-specification receiver-band noise (<-65 dBc/Hz) thanks to the high frequency resolution and small DNL.