Power gating structure having data retention and intermediate modes

Abstract

The present invention provides a power gating structure having data retention and intermediate modes and able to operate under multiple modes. A conventional power gating structure has only turn-on and turn-off functions, and is used to suppress a leakage current problem which has become more and more serious in advance manufacture processes, under a turn-off mode. However, in a memory circuit, such as latch, register and SRAM, when the power gate is turned off, a new power gating structure is required for data retention. The power gating structure of the present invention can be set into one of 4 different operational modes: a data retention mode for maintaining the static noise margin of the memory, an intermediate mode for reducing the interference on ground and power levels, an active mode used when the circuit operates in normal condition, and a standby mode used when the circuit does not operate.