Low voltage, low phase noise ring VCO design

Abstract

This thesis presents a ring VCO for low phase noise and wide tuning range. Since the phase noise of the ring VCO is inherently poor, many have tried to improve the phase noise. However, the formally proposed ring VCOs have the problem of large noise or frequency tuning at low supply voltage. In order to solve the problems at the low supply, a ring VCO is proposed. The proposed ring VCO reduces the noise current and is applied to negative skewed delay. Therefore, the phase noise and frequency tuning are improved. For verification of the idea, the proposed ring VCO is compared with two conventional ring VCO at low supply voltage. The proposed ring VCO shows the better performances (phase noise, frequency tuning) than that of two conventional ring VCOs. The proposed ring VCO is implemented in 65nm CMOS technology. The supply voltage is 1V as a low voltage. The proposed ring VCO oscillates from 401.7MHz to 882.6MHz. At near 400MHz, the phase noise of the proposed ring VCO is -78.04 and -107.4 dBc/Hz at 100 KHz and 1 MHz offset frequency, respectively. The proposed ring VCO consumes 6.1~8.5mA from 1V supply.