US 8,710,896 B2Granted

Sampling switch circuit that uses correlated level shifting

AssigneeFreescale Semiconductor, Inc.

InventorsSteven P. Allen, Mohammad Nizam U. Kabir

Life of this patent

Estimating the term…

Loading patent…

Abstract

A sampling switch circuit uses correlated level shifting. The sampling switch circuit includes: a sampling switch having a first terminal, a control terminal, and an output terminal, wherein the first terminal is connected to an input voltage node; a boosting circuit connected to first and second supply voltage nodes and coupled to the control terminal of the sampling switch; and a correlated level shifting buffer circuit. The correlated level shifting buffer circuit includes: an amplifier having first and second inputs and an output, wherein the first input is connected to the input voltage node, and the output and second input are coupled to the boosting circuit; and a level shifting capacitor coupled to the second input and output of the amplifier, to the boosting circuit, and to a level shifting voltage node.

Claims19

Dependent claims

A sampling switch circuit that uses correlated level shifting, the sampling switch circuit comprising:

a sampling switch having a first terminal, a control terminal, and an output terminal, wherein the first terminal is connected to an input voltage node;
a boosting circuit connected to first and second supply voltage nodes and coupled to the control terminal of the sampling switch;
a correlated level shifting buffer circuit comprising:
an amplifier having first and second inputs and an output, wherein the first input is connected to the input voltage node, and the output and second input are coupled to the boosting circuit;
and
a level shifting capacitor coupled to the second input and output of the amplifier, to the boosting circuit, and to a level shifting voltage node;
wherein when an input voltage is connected to the input voltage node, a first supply voltage is connected to the first supply voltage node, and a second supply voltage is connected to the second supply voltage node, the sampling switch circuit is configured to generate, using only one estimate phase and one level shift phase, a sampling signal at the control terminal of the sampling switch, wherein the sampling signal comprises a portion that is equal to the input voltage plus a difference between the first and second supply voltages.

4 more elements

A method for using correlated level shifting in a sampling switch circuit, the method comprising:

during a first clock phase:
receiving an input voltage into a correlated level shifting buffer circuit;
generating, in the correlated level shifting buffer circuit, an amplifier output voltage based on the input voltage;
storing a level shifting voltage and the amplifier output voltage in the correlated level shifting buffer circuit;
storing a first supply voltage and a second supply voltage in a boosting circuit;
during a second and next clock phase:
receiving the input voltage into the correlated level shifting buffer circuit and into an input terminal of a sampling switch;
level shifting the amplifier output voltage based on the level shifting voltage to supply to the boosting circuit a voltage level that is equal to the input voltage;
generating, by the boosting circuit, a sampling signal at a control terminal of the sampling switch, wherein the sampling signal has a value that is equal to the input voltage plus a difference between the first and second supply voltages, wherein the sampling signal turns on the sampling switch to allow the input voltage to pass from the input terminal to an output terminal of the sampling switch.

6 more elements

Dependencies are inferred from the claim text.