Comparison and Performance Analysis of Ring Oscillators and Current-Starved VCO in 180-nm CMOS Technology

This paper presents a comparative study between two Ring oscillators architecture (CMOS, NMOS) and current- starved Voltage-controlled oscillator (CS-VCO) on the basis of their performance parameters (Power consumption, Phase- Noise and Output Swing). All the design has been done in 180- nm CMOS technology node and 2.5 GHz Centre frequency have been opted for the comparison because of their applications in Wi-Fi and Bluetooth regime. An intuitive idea of the stated performance parameters has been achieved through the comparative study. The comparative data shows that NMOS based Ring oscillator is best option in terms of the phase noise performance. In this study NMOS Ring Oscillator have achieved a phase noise -72.94 dBc/Hz at 1 MHz offset frequency from 2.5 GHz centre frequency. The comparative data also mirrors that CMOS Ring oscillator is the best option in terms of power consumption. In this work CMOS Ring oscillator drained a power of 4.61 μW which is quite low.