Direct conversion receiver architecture
First Claim
1. An automatic gain control (AGC) apparatus operable during direct conversion of RF signals comprising:
- an analog variable gain amplifier for amplifying with a gain control value derived at least in part from a determined value of a DC offset of the baseband;
a digital variable gain amplifier coupled to an output of the analog variable gain amplifier;
a gain controller adapted to measure a signal strength and to control the gains of the analog and digital variable gain amplifiers; and
a DC offset canceller interposed between the output of the analog variable gain amplifier and an input of the digital variable gain amplifier, the DC offset canceller operative in a plurality of possible DC operating modes including an acquisition mode and a tracking mode, wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal.
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Accused Products
Abstract
A direct downconversion receiver architecture having a DC loop to remove DC offset from the signal components, a digital variable gain amplifier (DVGA) to provide a range of gains, an automatic gain control (AGC) loop to provide gain control for the DVGA and RF/analog circuitry, and a serial bus interface (SBI) unit to provide controls for the RF/analog circuitry via a serial bus. The DVGA may be advantageously designed and located as described herein. The operating mode of the VGA loop may be selected based on the operating mode of the DC loop, since these two loops interact with one another. The duration of time the DC loop is operated in an acquisition mode may be selected to be inversely proportional to the DC loop bandwidth in the acquisition mode. The controls for some or all of the RF/analog circuitry may be provided via the serial bus.
110 Citations
23 Claims
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1. An automatic gain control (AGC) apparatus operable during direct conversion of RF signals comprising:
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an analog variable gain amplifier for amplifying with a gain control value derived at least in part from a determined value of a DC offset of the baseband; a digital variable gain amplifier coupled to an output of the analog variable gain amplifier;
a gain controller adapted to measure a signal strength and to control the gains of the analog and digital variable gain amplifiers; anda DC offset canceller interposed between the output of the analog variable gain amplifier and an input of the digital variable gain amplifier, the DC offset canceller operative in a plurality of possible DC operating modes including an acquisition mode and a tracking mode, wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of operating an automatic gain control (AGC) loop in combination with a DC loop comprising:
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selecting a particular DC operating mode for the DC loop from among a plurality of possible DC operating modes that include an acquisition mode operable for a particular time duration inversely proportional across a loop bandwidth for the DC loop for the acquisition mode;
operating the DC loop in the selected DC operating mode to correct for DC offset in a signal;selecting a particular AGC operating mode for the AGC loop from among a plurality of possible AGC operating modes based on the selected DC operating mode; and
operating the AGC loop in the selected AGC operating mode to provide variable gain for the signal, the variable gain including control for RF circuitry derived at least in part from a determined value of a DC offset in a baseband of the signal, wherein the plurality of possible DC operating modes include the acquisition mode and a tracking mode, and wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A direct conversion receiver unit in a wireless communication system, comprising:
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a DC loop configurable to operate in one of a plurality of possible DC operating modes that include an acquisition mode operable for a particular time duration inversely proportional across a loop bandwidth for the DC loop for the acquisition mode to correct for DC offset in a signal; and an automatic gain control (AGC) loop configurable to operate in one of a plurality of possible AGC operating modes to provide variable gain for the signal, wherein the particular AGC operating mode to be used is determined based on the particular DC operating mode selected for use for the DC loop, the variable gain including control for RF circuitry derived at least in part from a determined value of a DC offset in a baseband of the signal, wherein the plurality of possible DC operating modes include the acquisition mode and a tracking mode, and wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal. - View Dependent Claims (14, 15)
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16. An apparatus, comprising:
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means for selecting a particular operating mode for a DC loop in a receiver unit from among a plurality of possible operating modes that include an acquisition mode; and means for, if the selected operating mode is the acquisition mode, operating the DC loop in the acquisition mode for a particular time duration to correct for DC offset in a desired signal, wherein the particular time duration is inversely proportional across a loop bandwidth for the DC loop for the acquisition mode, and transitioning out of the acquisition mode after the particular time duration into a tracking mode, wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal. - View Dependent Claims (17, 18, 19)
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20. A method, operable with a DC loop in a receiver unit, the DC loop comprising a first integrated circuit, the first integrated circuit comprising an analog variable gain amplifier and a DC offset canceller, and a second integrated circuit, the second integrated circuit comprising a digital variable gain amplifier, and a gain controller adapted to measure a signal strength and to control the gains of the analog and variable digital variable gain amplifiers, the method comprising:
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selecting a particular operating mode for the first integrated circuit from among a plurality of possible operating modes that include an acquisition mode; and if the selected operating mode is the acquisition mode, operating the first integrated circuit in the acquisition mode for a particular time duration to correct for DC offset in a desired signal, wherein the particular time duration is inversely proportional across a loop bandwidth for the DC loop for the acquisition mode, and transitioning out of the acquisition mode after the particular time duration into a tracking mode, wherein the acquisition mode has a wider loop bandwidth than that of the tracking mode and is used to more quickly remove a large DC offset in the signal. - View Dependent Claims (21, 22, 23)
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Specification