A Low-Jitter Cell-Based Digitally Controlled Oscillator With Differential Multiphase Outputs

A low-jitter digitally controlled oscillator (DCO) with multiphase differential outputs and good linearity is presented. The DCO is composed of four differential delay cells and can achieve linear tuning over a wide frequency range. The proposed fully differential delay cell comprises logic cells in standard library and varactors. The measured rms jitter and pk-pk jitter from 2.5-GHz carrier are 2.827 and 29 ps, respectively. The power consumption is 6 mW from a 1.2 V supply. An experimental prototype is designed using 65-nm CMOS technology, and the chip area is 156 μm × 92 μ².