Method and apparatus for automatic gain control in a digital receiver
First Claim
1. An automatic gain control apparatus comprising an adjustable gain amplifier, said adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, said automatic gain control apparatus comprising:
- means for generating a received power signal based on the power of said output signal;
saturating integrator means for comparing, in response to an integration enable signal, said received power signal to a reference signal and for generating said gain control signal; and
decision means for creating said integration enable signal in response to the value of said gain control signal, the value of said received power signal, and the value of said reference signal.
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Accused Products
Abstract
An automatic gain control (AGC) apparatus for a digital receiver is disclosed herein. The AGC apparatus includes an adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal. The AGC apparatus further includes a measurement circuit for generating a received power signal based on the power of the output signal. A saturating integrator compares the received power signal to a reference signal and generates an gain control signal in response to a result of the comparison. The saturating integrator includes a decision circuit for enabling integration based on values of the received power signal, the reference signal, and the gain control signal. In a preferred implementation the utilization of an input limiter in conjunction with an analog to digital converter enables accommodation of an increased input signal dynamic range. Accordingly, the AGC apparatus is capable of being used in digital demodulation of FM signals. The AGC apparatus may also be employed within a dual mode receiver designed to process both FM and code division multiple access (CDMA) input signals.
121 Citations
39 Claims
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1. An automatic gain control apparatus comprising an adjustable gain amplifier, said adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, said automatic gain control apparatus comprising:
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means for generating a received power signal based on the power of said output signal; saturating integrator means for comparing, in response to an integration enable signal, said received power signal to a reference signal and for generating said gain control signal; and decision means for creating said integration enable signal in response to the value of said gain control signal, the value of said received power signal, and the value of said reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for automatic gain control using an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control method comprising the steps of:
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generating a received power signal based on the power of said output signal; integrating in response to an integration enable signal the difference between said received power signal and a reference signal and generating said gain control signal; and providing said integration enable signal based on values of said received power, said reference signal, and said gain control signal. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A dual-mode digital receiver for processing signals from CDMA and FM cellular communication systems, the digital receiver having an automatic gain control apparatus comprising an adjustable gain amplifier wherein the adjustable gain amplifier comprises an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control apparatus comprising:
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select means for selecting a CDMA gain control mode and for selecting an FM gain control mode; first means for filtering the output signal upon selection of the CDMA gain control mode, and second means for filtering the output signal upon selection of the FM gain control mode; means for generating a received power signal based on power of the output signal; means for integrating the received power signal as compared to a reference signal and producing the gain control signal; and means for enabling the means for integrating based on values of the reference signal, the received power signal and the gain control signal.
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17. An automatic gain control apparatus including an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control apparatus comprising:
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means for generating a received power signal based on power of said output signal; saturating integrator means for comparing said received power signal to a reference signal and for generating an error signal in response to a result of the comparison, said saturating integrator means including means for providing said gain control signal by accumulating said error signal exclusively over one or more integration intervals and decision means for defining said one or more integration intervals based on values of said error and gain control signals. - View Dependent Claims (18, 19)
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20. An automatic gain control apparatus including an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control apparatus comprising:
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means for generating a received power signal based on power of said output signal; and saturating integrator means for comparing said received power signal to a reference signal and for generating an error signal in response to a result of the comparison, said saturating integrator means including means for providing said gain control signal by selectively integrating said error signal based on values of said error and gain control signals. - View Dependent Claims (21, 22, 23, 24, 31, 32, 33, 34)
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25. A method for automatic gain control using an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control method comprising the steps of:
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generating a received power signal based on power of said output signal; comparing said received power signal to a reference signal and generating an error signal in response to a result of the comparison; and providing said gain control signal by selectively integrating said error signal in accordance with values of said error and gain control signals. - View Dependent Claims (26, 27, 28, 29, 30)
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35. A dual-mode digital receiver for processing signals from CDMA and FM cellular communication systems, the digital receiver having an automatic gain control apparatus including an adjustable gain amplifier wherein the adjustable gain amplifier includes an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control apparatus comprising:
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select means for selecting a CDMA gain control mode and for selecting an FM gain control mode; first means for filtering said output signal upon selection of said CDMA gain control mode, and second means for filtering said output signal upon selection of said FM gain control mode; means for generating a received power signal based on power of said output signal; and means for comparing said received power signal to a reference signal and for generating an error signal in response to a result of the comparison; saturating integrator means for providing said gain control signal by selectively integrating said error signal based on values of said error and gain control signals.
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36. An automatic gain control apparatus including an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control apparatus comprising:
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means for generating a received power signal based on power of said output signal; and a saturating integrator having a first input for receiving a reference signal and a second input to which is switchably connected said received power signal, said saturating integrator being disposed to selectively integrate said received power signal so as to generate a gain control signal within a predefined control range. - View Dependent Claims (37, 38)
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39. A method for automatic gain control using an adjustable gain amplifier, the adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal, the automatic gain control method comprising the steps of:
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generating a received power signal based on power of said output signal; selectively integrating said received power signal so as to provide a gain control signal within a predefined control range wherein said selective integration of said received power signal is performed on the basis of magnitude of said gain control signal and on magnitude of said received power signal.
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Specification