Application of quasi floating-gate MOS transistor in the design of ring oscillator

Abstract

This paper presents the design of high performance ring oscillator using quasi floating-gate MOSFET (QFGMOS) which is suitable for low voltage and low power design in the modern submicron technologies. The floating gate MOSFET has been employed to make the frequency of oscillation tunable in the architecture of CMOS ring oscillator because of the dependence of its threshold voltage on the bias voltage. Since the presence of large capacitances in FGMOS structure prevents the generation of high frequency oscillations, so QFGMOS has been used to enhance the oscillation frequency of ring oscillator. It has been found from the comparative study of CMOS, FGMOS and QFGMOS ring oscillators that the frequency of oscillation of QFGMOS based ring oscillator is 8.33 GHz where as it is 6.7 GHz for FGMOS and 5 GHz for CMOS. The functionality of these circuits has been verified through PSpice simulations carried out using level 7 parameters in 0.13 μm CMOS technology with a supply voltage of 1 V and it conforms to the mathematical formulations.