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.

This paper presents a differential delay cell (DDC) for a 3-stage current-starved ring voltage-controlled oscillator (CSRVCO). In the proposed delay cell, pass transistors and a pair of back-to-back transistors are connected in a symmetric structure that helps get less jittery output by providing similar charging and discharging paths from the load capacitor. The current flows from similar paths with the same type and number of transistors in the proposed DDC-based CSRVCO. For verifying the DDC operation, the 3-stage CSRVCO using the proposed DDC is implemented with a standard 65nm CMOS technology with 1V supply. Post-layout simulation results confirm the correct operation of the proposed DDC using the CSRVCO with minimal jitter at the output. The proposed CSRVCO can be tuned from 0.88 GHz to 2.76 GHz. The phase noise of -94.54 dBc Hz was measured at 1MHz offset frequency for the center frequency of 2.76 GHz. The CSRVCO was designed using the proposed DDC occupied area 1198.43 μm2, and dissipated power is 5.19mW.