“…In real transistors current does not abruptly cut-off below threshold, but drops off exponentially as given by equation (1). This sub-threshold leakage current for V GS < V T is given by In these equations I DS0 is current at threshold( dependent on process and device geometry), V T0 is the zero bias threshold voltage, γ -is the linearized body effect coefficient, η represents the effect of V DS on threshold voltage, n is the sub- [4], Dual V T CMOS [5], DRG Cache [6], multiple power gating [7], sleepy keeper [8], VCLEART [9], LECTOR [10], GALLEOR [11], Sleepy Pass Gate [12], low leak stable SRAM [13], ultra low leak and state retention for inverters [14] , are some of the techniques for leakage reduction. Each method has its own merits and demerits.…”