Semiconductor integrated circuit having current leakage reduction scheme

Abstract

A semiconductor integrated circuit includes a CMOS controlled inverter consisting of series-connected PMOS and NMOS transistors. The source of the NMOS transistor is coupled to a ground line through an additional NMOS transistor for power gating of voltage VSS. The source of the PMOS transistor can be coupled to a power supply line through an additional PMOS transistor for power gating of voltage VDD. The inverter receives an input signal IN and its complementary version that has transitioned earlier than the input signal. In response to the input signal, the inverter produces an output signal. A NAND gate that receives the output signal and the complementary input signal controls the power gating NMOS transistor. A NOR gate that receives the output signal and the complementary input signal controls the power gating PMOS transistor. The power gating to the CMOS inverter is performed by feedback of the output signal and the complementary input signal, with the result that current leakage reduction through the CMOS controlled inverter is achieved. A self leakage reduction with power gating transistors is applicable to another type of logic gates such as NAND, NOR and Exclusive-OR, AND, OR.