Patent ID: 7978004

Claim:
A sub-circuit power supply circuit comprising: a first voltage rail that is adapted to provide a first voltage; a second voltage rail that is adapted to provide a second voltage; a third voltage rail that is adapted to provide a third voltage; a fourth voltage rail that is adapted to provide a fourth voltage; a first supply voltage output; a second supply voltage output; a footer circuit that is coupled to the third voltage rail, the fourth voltage rail, and the second supply voltage output; and a header circuit having: a transistor having a source, a drain, a gate, and body, wherein the source of the transistor is coupled to the first voltage rail, and wherein the drain of the transistor is coupled to the first supply voltage output, and wherein the gate of the transistor responsive to an activation signal so as to couple the first voltage rail to the first supply voltage output; and a connection unit that is coupled to the second voltage rail, the body of the transistor and the first supply voltage output, wherein the connection unit is responsive to the activation signal to couple the body of the transistor to the first supply voltage output so as to bias the body of the transistor to lower a threshold voltage of the transistor when the transistor is turned on, and to couple the body of the transistor to the second voltage rail to bias the body of the transistor to raise the threshold voltage when the transistor is turned off.