Texas Instruments Corporation

Richard David Nicholson

Bradford Lawrence Hunter

Tsing Hsu

Hakan Oner

Wallace Edward Matthews

The disclosure presented herein provides example embodiments of systems for accurate multiplexing. The systems and methods presented may be suitable for non-limiting examples of analog to digital conversion with a switched input voltage (for a switched capacitor application) or any circuit with high voltage/high accuracy voltage multiplexing. In an example embodiment, pulsed current sources may be implemented to rapidly turn on and turn off the selected and unselected multiplexer ports while maintaining relatively low power consumption. A Kelvin input port may allow a high voltage input to be accurately sensed by avoiding a voltage drop associated with a selected pass gate p-channel FET channel resistance and parasitic wire resistance. The Kelvin input port biases the gate of a pass FET structure whose body terminals are allowed to remain floating.

Systems for accurate multiplexing

A regulated charge pump power supply is implemented with a QP regulation loop providing QP clocking to control pumping operation based on sensing output voltage using residual charge on a flying capacitor Cfly. Cfly is used not only in normal charge pumping operation as an active charge shuttle element, but also to determine/measure output voltage VOUT. Voltage sensing using measured residual charge on Cfly is accomplished by introducing a sample phase into the normal charge pumping operation&#x2014;after the pump phase and before the charge phase. In the sample phase, VOUT is determined (sampled) based on the residual charge on Cfly corresponding to (Vsense=VOUT&#x2212;VIN). During the sample phase, the Cfly bottom plate is connected to ground, and the Cfly top plate is sampled (such as with a sense capacitor), with the sample phase completed prior to initiating a charge phase (by connecting the Cfly top plate to VIN).

Charge pump power supply with output voltage sensing using residual charge on a flying capacitor

Systems and devices for dynamically scaled charge pumping are presented. Example embodiments of the disclosed systems of dynamically scaled charge pumping enable regulation of the output voltage at a particular ratio and to dynamically control the ratio based on the input voltage. A charge pumping circuit is enabled by an oscillator. The charge pump oscillator is enabled by the output of a comparator. The comparator compares an input voltage to a comparator voltage, which is a divided version of the output voltage. The output voltage is referenced to a regulated voltage and the comparison voltage is divided between the two voltages by a resistor divider. The regulated voltage remains flat until the input voltage equals the reference voltage. At that point, the regulated voltage will begin to rise and follow the input voltage. Before the reference voltage is reached, the output voltage equals the input voltage multiplied by the resistor divider ratio. Once the input voltage reaches the reference voltage, the difference between the output voltage and the input voltage becomes a constant.

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Austin, TX, United States of America

Richard David Nicholson