Switch bootstrapping for precise sampling beyond supply voltage

Bootstrapped switches are used in a variety of applications including DC-DC converters, pipelined analog-to-digital converters and high voltage switches and drivers. Current work on highly integrated power management applications often requires the ability to measure voltage quantities that exceed the supply voltage in magnitude. This is primarily due to a basic need to maximize efficiency by running the power management IC on as low supply voltage as possible, while still maintaining the ability to sample and measure quantities from the surroundings that could well exceed the battery voltage. In this paper, a new bootstrapped switch is presented. The switch enables the precise sampling of input signals well greater than the chip supply voltage with no static power consumption, and without activating on-chip parasitic body diodes. The bootstrapped switch, presented here, is designed to sample an input signal with a 0-5.5-V range at a supply voltage of 2.75 V. Measurement data shows functionality for a 0-6-V input signal range with a supply voltage as low as 1.2 V.