Design and Analysis of Self-Tanked Stepwise Charging Circuit for Four-Phase Adiabatic Logic

Abstract

Adiabatic logic has been proposed as a method for drastically reducing power consumption in specialized low-power circuits. They often require specialized clock drivers that also function as the main power supply, in contrast to standard CMOS logic, and these power clocks are often a point of difficulty in the design process. A novel, stepwise charging driver circuit for four-phase adiabatic logic is proposed and validated through a simulation study. The proposed circuit consists of two identical driver circuits each driving two opposite adiabatic logic phases. Its performance relative to ideal step-charging and a standard CMOS across mismatched phase loads is analyzed, and new best practices are established. It is compared to a reference circuit consisting of one driver circuit for each phase along with a paired on-chip tank capacitor. The proposed driver uses opposite logic phases to act as the tank capacitor for each other in a “self-tanked” fashion. Each circuit was simulated in 15 nm FinFET across a variety of frequencies for an arbitrary logic operation. Both circuits showed comparable power consumption at all frequencies tested, yet the proposed driver uses fewer transistors and control signals and eliminates the explicit tank capacitors entirely, vastly reducing circuit area, complexity, and development time.