Design of Linear Low-Power Voltage-Controlled Oscillator with I-MOS Varactor and Back-Gate Tuning

Abstract

This paper reports a new design of CMOS voltage-controlled oscillator (VCO) using three-transistor XOR gate and inversion mode MOSFET varactor tuning concept. Output frequency in the VCO has been varied by varying the output node capacitance with the use of inversion mode MOSFET tuning and back-gate tuning. Further, variation in the output frequency has been obtained with the power supply tuning for different value of back-gate voltages. Inversion mode MOSFET tuning has been achieved by varying the source/drain voltage from 0.6 to 2.2 V which provides the frequency variation from 1.630 to 1.232 GHz with power consumption of 296.393 $$\upmu \hbox {W}$$ for inversion mode MOS varactor width of 5 $$\upmu \hbox {m}$$ . Results have also been obtained with inversion mode MOS varactor widths of 8 and 10 $$\upmu \hbox {m}$$ . Output frequency, power consumption and phase noise results have also been reported for the different values of back-gate and power supply voltages. A tuning range of 27.8, 32.7 and 34.3% has been achieved with the source/drain tuning for inversion mode MOS varactor width of 5, 8 and 10 $$\upmu \hbox {m}$$ , respectively. Moreover in power supply tuning the tuning range of approximately 134% has been obtained for different widths of inversion mode MOS varactor. VCO is showing the phase noise of $$-\,97.216$$ dBc/Hz with an offset of 1 MHz from the carrier. Proposed VCO shows a linear tuning, low-power consumption and good phase noise performance.