Source transistor configurations and control methods

Abstract

Source transistor configurations are described for reducing leakage and delay within integrated circuits. Virtual power and ground nodes are supported with the use of stacked transistor configurations, such as a two transistor stack between a first virtual supply connection and VSS, and a second virtual supply connection and VDD. Gate drives of these stacked transistors are modulated with different voltage levels in response to the operating power mode of the circuit, for example active mode, active-standby mode, and deep power-down mode. Means for driving these source stacks are described. In one embodiment separate virtual nodes are adapted for different types of circuits, such as buffers, row address strobe, and column address strobe. Other techniques, such as directional placement of the transistors is also described.