Patent ID: 8228109

Claim:
A transmission gate circuit, the transmission gate circuit comprising: a first transmission gate comprising a first switching device having a first current electrode, a second current electrode, and a control electrode; a second transmission gate comprising a second switching device having a first current electrode, a second current electrode, and a control electrode, and wherein the first current electrode of the second switching device is coupled to the second current electrode of the first switching device; a first terminal coupled to the first current electrode of the first switching device; a second terminal coupled to the second current electrode of the second switching device; and control circuitry coupled to the first transmission gate and the second transmission gate, wherein in a first mode, the control circuitry places the first transmission gate and the second transmission gate into a conductive state to provide a conductive path between the first terminal and the second terminal through the first transmission gate and the second transmission gate, and when the control circuitry is in a second mode, the control circuitry places the first transmission gate and the second transmission gate into a non-conductive state, wherein when the control circuitry is in the second mode and a voltage of the first terminal is outside a safe operating voltage area of at least one of the first switching device and the second switching device, the first switching device remains within its safe operating voltage area and the second switching device remains within its safe operating voltage area; wherein the first switching device is further characterized as a first PMOS transistor, and wherein the second switching device is further characterized as a second PMOS transistor, wherein the first transmission gate comprises a first NMOS transistor coupled in parallel with the first switching device and the second transmission gate comprises a second NMOS transistor coupled in parallel with the second switching device.