Design and Analysis of Wide Tuning Range Ring VCO in 65nm CMOS Technology

Abstract

In this article a ring voltage controlled oscillator (VCO) with four stages consisting of differential delay cells with two control voltages is proposed. This VCO uses the dual-delay loop technique for high operation frequency. Each delay cell of the proposed VCO includes two pairs of PMOS and NMOS cross-coupled load transistors to form a latch. The strength of the added latch and the operation frequency are adjusted with a pair cross-coupled NMOS pass transistors. Furthermore, to adjust the frequency of the proposed VCO in higher frequencies, the effect of the secondary path of this VCO is changed. The proposed VCO is simulated in 65nm TSMC CMOS technology in Cadence software and 1.2 V supply voltage. The wide tuning range of the proposed VCO varies from 4.25 to 21.31 GHz (80.07%), its power is 12.36 mW at 4.25 GHz frequency. The phase noise is −90.47 dBc/Hz at 1 MHz offset frequency and −117.4 dBc/Hz at 10 MHz offset frequency from 4.25 GHz while its area is 535.99 µm².