Wide tunable CMOS multiple-nested-feedback ring type L-C oscillator

Abstract

A new CMOS multiple-nested-feedback ring type L-C oscillator (MFLCO) is presented. The new oscillator shows a wide tuning range and fast speed at low voltage operation. The phase noise is expected to be approximately that of a monolithic L-C oscillator. For three and four-stage MFLCOs, 200 MHz and 520 MHz tuning ranges are achieved without varactor diodes, respectively. The maximum speed exceeds 3 GHZ, which reaches approximalely f(T)/3 with 0.8 mu m CMOS technology. The proposed oscillators are suitable for RF frequency synthesisers and multiphase applications.