A 20kHz frequency resolution DCO

This paper reports a Digitally Controlled Oscillator (DCO) with 20kHz frequency resolution. This is the first DCO implementing capacitor delta tuning and Dynamic Element Matching (DEM) to suppress process variations and mismatches between small capacitor deltas. The DCO is fabricated in 0.13μm CMOS IBM technology. The proposed DEM technique reduced the process variations and mismatches from 95% to 33.5% for the minimum capacitance step. The oscillator has a frequency tuning range from 108MHz to 133MHz with a centre frequency at 120.5MHz and forms part of an RF injection locked oscillator. The output frequency is covered by 8192 tuning steps. The measured frequency characteristics are provided in this paper. The DCO consumes 1.7mW power from a 1.185V voltage supply.