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US 2018/0205402 A1Published application
Spur cancellation system for modems
AssigneeCypress Semiconductor Corporation
InventorsYan Li, Wendy Yu, Kamesh Medapalli, Hongwei Kong, Patrick Cruise
Life of this patent
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Abstract
A modem includes a modulator and a demodulator. The demodulator includes a direct current removing (DCR) circuit to transition between an acquisition mode, where the DCR circuit operates with a first loop gain; and a tracking mode, where the DCR circuit operates with a second loop gain. The second loop gain is smaller than the first loop gain, and the timing of the transition between the acquisition mode and tracking mode is programmable.
Claims20
A demodulator, comprising:
- a receiver;
- and
- a direct current removing (DCR) circuit, the DCR circuit transitions between:
- an acquisition mode, wherein the DCR circuit operates with a first loop gain to identify a spur resulting from a clock frequency;
- and
- a tracking mode, wherein the DCR circuit operates with a second loop gain,
- wherein:
- the second loop gain is smaller than the first loop gain;
- a timing of the transition between the acquisition mode and tracking mode is programmable;
- and
- the DCR circuit re-identifies the spur whenever the receiver is cycled from an off power state to an on power state.
8 more elements
A demodulator, comprising:
- a receiver;
- and
- a direct current removing (DCR) circuit, the DCR circuit transitions among:
- an acquisition mode, wherein the DCR circuit operates with a first loop gain to identify a spur resulting from a clock frequency;
- a tracking mode, wherein the DCR circuit operates with a second loop gain;
- and
- a holding mode, wherein the DCR circuit freezes a loop gain of the DCR circuit for data demodulation,
- wherein:
- the second loop gain is smaller than the first loop gain;
- a timing of the transition between the acquisition mode and tracking mode is programmable;
- the transition to the holding mode occurs upon completion of synchronization;
- and
- the DCR circuit re-identifies the spur, beginning with the frozen loop gain, whenever the receiver is cycled from an off power state to an on power state.
10 more elements
A method for demodulating a signal, comprising:
- placing a direct current removing (DCR) circuit into an acquisition mode having a first loop gain;
- setting an acquisition mode timer;
- identifying a spur resulting from a clock frequency;
- placing the DCR circuit into a tracking mode having a second loop gain based on at least one of the acquisition mode timer expiring or identifying the spur;
- and
- re-identifying the spur whenever a receiver is cycled from an off power state to an on power state,
- wherein the second loop gain is smaller than the first loop gain.
4 more elements
Dependencies are inferred from the claim text.