Variable Threshold MOSFET Approach (Through Dynamic Threshold MOSFET) For Universal Logic Gates

TL;DR

This paper introduces a Variable Threshold MOSFET (VTMOS) approach derived from DTMOS to significantly reduce power consumption in sub-threshold digital circuits, outperforming CMOS and DTMOS in power efficiency and delay.

Contribution

The paper proposes a novel VTMOS technique that dynamically biases the substrate to lower power consumption in sub-threshold logic circuits, demonstrating improved performance over existing methods.

Findings

VTMOS reduces power dissipation by up to 50% compared to CMOS and DTMOS.

VTMOS maintains similar switching characteristics to DTMOS while lowering power.

Performance parameters depend on frequency, with VTMOS showing superior power-delay metrics.

Abstract

In this article, we proposed a Variable threshold MOSFET(VTMOS)approach which is realized from Dynamic Threshold MOSFET(DTMOS), suitable for sub-threshold digital circuit operation. Basically the principle of sub- threshold logics is operating MOSFET in sub-threshold region and using the leakage current in that region for switching action, there by drastically decreasing power. To reduce the power consumption of sub-threshold circuits further, a novel body biasing technique termed VTMOS is introduced .VTMOS approach is realized from DTMOS approach. Dynamic threshold MOS (DTMOS) circuits provide low leakage and high current drive, compared to CMOS circuits, operated at lower voltages. The VTMOS is based on operating the MOS devices with an appropriate substrate bias which varies with gate voltage, by connecting a positive bias voltage between gate and substrate for NMOS and negative bias voltage between gate and substrate for PMOS. With VTMOS, there is a considerable reduction in operating current and power dissipation, while the remaining characteristics are almost the same as those of DTMOS. Results of our investigations show that VTMOS circuits improves the power up to 50% when compared to CMOS and DTMOS circuits, in sub- threshold region.. The performance analysis and comparison of VTMOS, DTMOS and CMOS is made and test results of Power dissipation, Propagation delay and Power delay product are presented to justify the superiority of VTMOS logic over conventional sub-threshold logics using Hspice Tool. The dependency of these parameters on frequency of operation has also been investigated.