Frequency Range Enhancement in Differential Ring VCO while Maintaining Phase Noise Performance

Abstract

<p>This paper presents a differential delay cell-based ring voltage-controlled oscillator (RVCO). The proposed RVCO (PRVCO) introduces auxiliary charging and discharging paths in conventional ring VCO (CRVCO) that enhance the maximum operating frequency and frequency range. Adding auxiliary paths does not increase the maximum current in PRVCO within different time instants in one period compared to other available RVCOs. Thus, it maintains the phase noise performance. The post-layout simulations of the four-stage PRVCO were performed in 65nm CMOS technology with 1V supply voltage. The maximum operating frequency of the four-stage CRVCO, and PRVCO, are 585MHz and 3.2 GHz, respectively. The PRVCO improves the maximum operating frequency significantly compared to CRVCO. The PRVCO has a linear tuning range from 1.8 GHz to 3.2 GHz, which is 78% better than the CRVCO. The phase noise of the PRVCO is -103.8 dBc/Hz at an offset frequency of 1 MHz. The figure of merit (FoM) is improved by 11 dB compared to CRVCO in the same technology node of 65nm CMOS.</p>