Methods and apparatus for a track and hold amplifier
AssigneeSemiconductor Components Industries, LLC
InventorShankar Ramakrishnan
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Abstract
Various embodiments of the present technology may provide methods and apparatus for a track-and-hold amplifier configured to sample and amplify an analog signal. Methods and apparatus for a track-and-hold amplifier according to various aspects of the present invention may provide an isolation circuit configured to isolate transient current in a track-and-hold capacitor during a track phase. According to various embodiments, selective activation of the isolation circuit provides a settling time that is independent of the gain of the amplifier.
Claims19
A track-and-hold amplifier circuit, comprising:
- a gain setting circuit configured to receive an input signal;
- a cascode circuit comprising a first terminal, a second terminal, and a third terminal, wherein the cascode circuit is connected to:
- the gain setting circuit at a first node via the first terminal, and at a second node via the second terminal;
- and
- a ground node via the third terminal;
- a track-and-hold capacitor comprising:
- a first capacitor terminal connected to an output node, wherein the output node is selectively connected to the first node;
- and
- a second capacitor terminal;
- and
- an isolation circuit connected to the second capacitor terminal at a third node and the ground node, and wherein the isolation circuit and the cascode circuit share a fourth node.
A system, comprising:
- a plurality of pixel columns;
- a plurality of track-and-hold amplifier circuits, wherein:
- each pixel column is connected to one track-and-hold amplifier circuit from the plurality of track-and-hold amplifier circuits;
- and
- each track-and-hold amplifier circuit comprises:
- a gain setting circuit configured to receive an input signal;
- a cascode circuit connected to the gain setting circuit at a first node and a second node;
- a track-and-hold capacitor comprising:
- a first capacitor terminal connected to an output node, wherein the output node is selectively connected to the first node;
- and
- a second capacitor terminal;
- and
- an isolation circuit connected to:
- the second capacitor terminal at a third node;
- the cascode circuit at a fourth node;
- and
- a ground node.
A track-and-hold amplifier circuit, comprising:
- a gain setting circuit configured to receive an input signal;
- a cascode circuit connected to the gain setting circuit at a first node and a second node;
- a track-and-hold capacitor comprising:
- a first capacitor terminal connected to an output node, wherein the output node is selectively connected to the first node;
- and
- a second capacitor terminal;
- and
- an isolation circuit comprising:
- a transistor connected to:
- the second capacitor terminal at a third node;
- and
- the cascode circuit at a fourth node;
- and
- a clamp device connected to:
- the fourth node;
- and
- a ground node;
- and
- a switch connected between the fourth node and the ground node.
Dependencies are inferred from the claim text.