Offset compensation in a receiver
AssigneeAnalog Devices, Inc.
InventorsKevin Glenn Gard, Robert C. Glenn
Life of this patent
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Abstract
Aspects of this disclosure relate to compensating for an offset in a receiver. In one embodiment, the receiver comprises a mixer, a feedback amplifier, and an offset correction circuit. The offset correction circuit can generate an indication of an offset in a differential input to the feedback amplifier and apply an offset compensation signal at an offset compensation node. The offset compensation node can be in a signal path of the feedback amplifier. Such offset compensation can reduce or eliminate leakage from a local oscillator at an input port of the mixer and/or at an antenna port of the receiver.
Claims20
An apparatus comprising a receiver with offset compensation, the receiver comprising:
- a mixer configured to downconvert an input signal and generate a differential signal;
- an amplifier configured to amplify the differential signal;
- a feedback path between an output terminal of the amplifier and an input terminal of the amplifier, the feedback path comprising a feedback element electrically connected to a feedback node disposed between the mixer and the input terminal of the amplifier;
- and
- an offset compensation circuit configured to:
- generate an indication of an offset in the differential signal;
- and
- apply, based at least partly on the indication of the offset in the differential signal, an offset compensation signal at an offset compensation node configured to receive a signal based on at least a combination of an output signal provided by the mixer and a feedback signal provided by the feedback path, wherein the offset compensation node is in a signal path between the feedback node and the output terminal of the amplifier, and wherein the offset compensation circuit is separate from the feedback path.
An apparatus with offset compensation, the apparatus comprising:
- a local oscillator configured to generate a local oscillator output;
- a mixer coupled to the local oscillator, the mixer configured to downconvert a radio frequency signal based at least partly on the local oscillator output;
- an amplifier configured to receive an output from the mixer at an input terminal of the amplifier;
- a feedback path comprising a feedback element coupled between an output terminal of the amplifier and the input terminal of the amplifier, wherein the feedback element is electrically connected to a feedback node disposed between the mixer and the input terminal of the amplifier;
- and
- an offset compensation circuit configured to:
- generate an indication of an offset present at the input terminal of the amplifier;
- and
- apply, based at least partly on the indication of the offset, an offset compensation signal at an offset compensation node configured to receive a signal based on at least a combination of an output signal provided by the mixer and a feedback signal provided by the feedback path, wherein the offset compensation node is in a signal path between the feedback node and the output terminal of the amplifier, and wherein the feedback path is separate from the offset compensation circuit;
- wherein the offset compensation signal is configured to cause leakage current from the local oscillator at an input port of the mixer to be reduced.
An electronically implemented method of compensating for an offset in a receiver, the method comprising:
- providing, by a passive mixer of a receiver, a differential signal to input terminals of a transimpedance amplifier, wherein the transimpedance amplifier comprises an amplifying circuit and a feedback path between one of the input terminals and an output terminal of the transimpedance amplifier, wherein the feedback path comprises a feedback element electrically coupled to a feedback node disposed between the passive mixer and the one of the input terminals;
- detecting an offset in the differential signal received by the transimpedance amplifier;
- and
- applying an offset compensation signal to a combined signal at an offset correction node to compensate for the detected offset, wherein the combined signal is a combination of at least an output signal from the passive mixer and a feedback signal from the feedback path, and wherein the offset correction node is in a signal path between the feedback node and an output of the transimpedance amplifier.
Dependencies are inferred from the claim text.