A 2.4-GHz Digitally Controlled Ring Oscillator Based on MOS Capacitors

This paper presents a digitally controlled ring oscillator (DCRO) which has a high frequency resolution. The proposed oscillator includes three tuning stages and regulates its frequency by using MOS capacitors in the output of each delay cell. The DCRO implemented in a 130 nm CMOS process operates at the center frequency of 2.4 GHz under a supply of 1.2 V. The phase noise of the presented DCRO at 1 MHz offset frequency is -106.3 dBc/Hz and the power consumption is 0.58 mW. The figure of merit obtained for the DCRO is -176.3 dBc/Hz.