US 6,642,751 B1Granted

Configurable track-and-hold circuit

AssigneeXilinx, Inc.

InventorPatrick J. Quinn

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Abstract

A track-and-hold circuit including a pair of circuits each receiving input signals and providing half of a differential output signal. Each of the circuits of the pair includes an amplifier, and a configurable switch circuit coupled to a selectable reference voltages based on an expected input signal type. Each circuit includes a first switched capacitor circuit to sample its respective first input signal in response to a first clock phase, and to couple the sampled first input signal between the output and the negative input of the amplifier in response to a second clock phase. A second switched capacitor circuit samples its respective second input signal relative to an external common mode voltage in response to the first clock phase, and couples the sampled second input signal to a positive amplifier input relative to the selected reference voltage in response to the second clock phase. The amplifiers collectively provide a differential version of the difference between the sampled input signals as shifted by the selected reference voltage.

Claims33

Dependent claims

A track-and-hold circuit comprising:

(a) a pair of circuits each receiving first and second input signals and providing half of a differential output signal, wherein the first and second input signals received by each respective circuit are reversed relative to each other, and wherein each circuit comprises:
(i) an amplifier;
(ii) a configurable switch circuit coupled to a selected one of a plurality of selectable reference voltages based on a predetermined input signal type;
(iii) a first switched capacitor circuit to sample its respective first input signal relative to an external common mode voltage in response to a first clock phase, and to couple the sampled first input signal in a feedback configuration between an output and a negative input of the amplifier in response to a second clock phase;
and
(iv) a second switched capacitor circuit to sample its respective second input signal relative to the external common mode voltage in response to the first clock phase, and to couple the sampled second input signal to a positive input of the amplifier relative to the selected one of the selectable reference voltages in response to the second clock phase;
(b) wherein the amplifiers of the circuit pair collectively provide the differential output signal as a differential version of the difference between the sampled first and second input signals as shifted by the selected one of the selectable reference voltages.

4 more elements

A track-and-hold circuit, comprising:

(a) a first circuit comprising:
(i) a first amplifier having an output to provide a first half of a differential output signal;
(ii) first and second sampling circuits to respectively sample first and second input signals relative to an external common mode voltage in response to a first clock phase;
(iii) a first switching circuit coupled to the first amplifier to provide the sampled first input signal to a negative input of the first amplifier;
(iv) a first configurable switch circuit to select one of a plurality of selectable reference voltages based on an input signal type;
and
(v) a second switching circuit coupled between the first configurable switch circuit and the first amplifier to provide the sampled second input signal to a positive input of the first amplifier relative to the selected one of the selectable reference voltages in response to a second clock phase;
(b) a second circuit comprising:
(i) a second amplifier having an output to provide a second half of the differential output signal;
(ii) third and fourth sampling circuits to respectively sample the second and first input signals relative to the external common mode voltage in response to the first clock phase and contemporaneously with sampling by the first and second sampling circuits;
(iii) a third switching circuit coupled to the second amplifier to provide the sampled second input signal to a negative input of the second amplifier;
(iv) a second configurable switch circuit to select one of a plurality of selectable reference voltages based on the input signal type;
and
(v) a fourth switching circuit coupled between the second configurable switch circuit and the second amplifier to provide the sampled first input signal to a positive input of the second amplifier relative to the selected one of the selectable reference voltages in response to the second clock phase;
and
(c) wherein the first and second amplifiers collectively output the differential output signal as a differential version of the difference between the first and second input signals as offset by the selected one of the selectable reference voltages.

13 more elements

Dependencies are inferred from the claim text.