Patent ID: 8525574

Claim:
Apparatus having a bootstrap switch circuit comprising: a switch device connected between an input node and an output node; a first capacitor connected between the input node and a gate of the switch device; and bootstrap circuitry selectively interconnecting a first plate of the first capacitor to the gate of the switch device and a second plate of the first capacitor to the input node, wherein: during a first phase, the bootstrap circuitry is configured to (i) turn off the switch device and (ii) charge the first capacitor to a pre-charge voltage level which is no higher than a supply voltage level; during a second phase, the bootstrap circuitry is configured to (i) cease charging the first capacitor and (ii) connect the first capacitor between the input node and the gate of the switch device, such that a voltage difference between the gate and a channel node of the switch device is maintained at or below a voltage tolerance level for the switch device; and the bootstrap circuitry comprises: a first switch connected between a first supply voltage node and the first plate of the first capacitor, wherein a gate of the first switch is connected to the gate of the switch device; a second switch connected between the second plate of the first capacitor and a second supply voltage node; a third switch connected between the second plate of the first capacitor and the input node; a first inverter connected between the first supply voltage node and the second plate of the first capacitor; and a second inverter connected to an output signal of the first inverter and connected between the first and second plates of the first capacitor, wherein an output signal of the second inverter is connected to the gate of the switch device.