LOW POWER SINGLE ENDED VCO DESIGN WITH IMOS VARACTOR FOR WIRELESS APPLICATIONS

Abstract

This article presents a low power single-ended voltage-controlled oscillator (VCO) design with an inversion mode MOS (IMOS) varactor in delay stages. VCO consists of two complementary metal-oxide-semiconductor (CMOS) inverters with a PMOS transistor as a bridge to create a single-ended VCO design. The output frequency tuning has been carried out at different bias voltage of bridge transistor along with the varying tuning voltage of the IMOS varactor connected at the output nodes to achieve constant power dissipation and wider tuning range. This VCO achieves a frequency tuning range of 31% from 2.335 GHz to 3.181 GHz and power dissipation of 0.710 mW for 1.8V power supply. The results with different width of the IMOS varactor show that frequency decreases with an increase in varactor width. Proposed VCO tunes the output frequency with IMOS varactor loading without changing the overall power dissipation of the circuit. The proposed VCO circuit shows a phase noise of -93.45 dBc/Hz at 1 MHz offset with the corresponding figure of merit (FoM) of -153.47 dBc. A comparison with earlier reported VCOs shows that proposed VCO provides an improvement in performance.