Linearized digital automatic gain control
First Claim
1. A linearized digital control apparatus for automatic gain control (AGC) in a radio having a transmit AGC amplifier and a receive AGC amplifier, the apparatus comprising:
- a received signal strength detector, coupled to the receive AGC amplifier, for generating a digital power level signal from a received signal;
an integrator, coupled to the received signal strength detector, for generating a digital AGC adjust signal;
a receive linearizer having a plurality of receive slope values and a plurality of receive offset values, coupled to the integrator, for generating a linearized receive adjust signal in response to one of the plurality of receive slope values and one of the plurality of receive offset values;
a receive digital to analog converter coupled to the receive linearizer for converting the linearized receive adjust signal into an analog receive adjust signal, the analog receive adjust signal controlling the gain of the receive AGC amplifier;
a transmit linearizer having a plurality of transmit slope values and a plurality of transmit offset values, coupled to the integrator, for generating a linearized transmit adjust signal in response to one of the plurality of transmit slope values and one of the plurality of transmit offset values; and
a transmit digital to analog converter coupled to the transmit linearizer for converting the linearized transmit adjust signal into an analog transmit adjust signal, the analog transmit adjust signal controlling the gain of the transmit AGC amplifier.
1 Assignment
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Accused Products
Abstract
The present invention provides linear, digital automatic gain control (AGC) in a radio. A received signal is demodulated to provide I and Q digital baseband signals. A received signal strength indication is determined from these signals and the resulting digital signal is adjusted to provide a logarithmic response. This signal is then integrated to provide a digital receive AGC adjust signal. For the transmit AGC adjust, the digital receive AGC adjust signal is filtered and then summed with a scaled closed loop power control command. The closed loop power control commands are ignored if they would result in increasing the transmit gain beyond the amplifier'"'"'s designed maximum output. The result of the sum operation converted from digital to analog for adjusting the amplifier. The outputs of the transmit and receive AGC amplifiers are linearized by transmit and receive linearizers, respectively, which pre-distort the digital AGC adjust signals prior to digital to analog conversion.
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Citations
14 Claims
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1. A linearized digital control apparatus for automatic gain control (AGC) in a radio having a transmit AGC amplifier and a receive AGC amplifier, the apparatus comprising:
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a received signal strength detector, coupled to the receive AGC amplifier, for generating a digital power level signal from a received signal; an integrator, coupled to the received signal strength detector, for generating a digital AGC adjust signal; a receive linearizer having a plurality of receive slope values and a plurality of receive offset values, coupled to the integrator, for generating a linearized receive adjust signal in response to one of the plurality of receive slope values and one of the plurality of receive offset values; a receive digital to analog converter coupled to the receive linearizer for converting the linearized receive adjust signal into an analog receive adjust signal, the analog receive adjust signal controlling the gain of the receive AGC amplifier; a transmit linearizer having a plurality of transmit slope values and a plurality of transmit offset values, coupled to the integrator, for generating a linearized transmit adjust signal in response to one of the plurality of transmit slope values and one of the plurality of transmit offset values; and a transmit digital to analog converter coupled to the transmit linearizer for converting the linearized transmit adjust signal into an analog transmit adjust signal, the analog transmit adjust signal controlling the gain of the transmit AGC amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A linearized digital control apparatus for automatic gain control (AGC) in a radio having a transmit AGC amplifier and a receive AGC amplifier, the transmit AGC amplifier being coupled to a power amplifier, a low noise amplifier being coupled to the receive AGC amplifier through a bandpass filter, the apparatus comprising:
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a received signal strength detector, coupled to the receive AGC amplifier, for generating a digital power level signal from a received signal, the digital power level signal being adjusted to provide a logarithmic response; an integrator, coupled to the receive signal strength detector, for generating a digital AGC adjust signal; a filter, coupled to the integrator, for filtering the digital AGC adjust signal; a low noise amplifier gain control, coupled to the integrator and the low noise amplifier, for adjusting the gain of the low noise amplifier; a receive linearizer having a plurality of receive slope values and a plurality of receive offset values, coupled to the low noise amplifier gain control, for generating a linearized receive adjust signal in response to one of the plurality of receive slope values and one of the plurality of receive offset values; a receive digital to analog converter coupled to the receive linearizer for converting the linearized receive adjust signal into an analog receive adjust signal, the analog receive adjust signal controlling the gain of the receive AGC amplifier; a transmit power limiting circuit, coupled to the filter, for limiting the digital AGC adjust signal to a maximum gain adjustment; a transmit linearizer having a plurality of transmit slope values and a plurality of transmit offset values, coupled to the integrator and transmit power limiting circuit, for generating a linearized transmit adjust signal in response to one of the plurality of transmit slope values and one of the plurality of transmit offset values; and a transmit digital to analog converter coupled to the transmit linearizer for converting the linearized transmit adjust signal into an analog transmit adjust signal, the analog transmit adjust signal controlling the gain of the transmit AGC amplifier.
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13. A method for linearized digital automatic gain control (AGC) in a radio having a transmit AGC amplifier, a receive AGC amplifier, a transmit linearizer having a plurality of transmit slope values and a plurality of transmit offset values, and a receive linearizer having a plurality of receive slope values and a plurality of receive offset values, the method comprising the steps of:
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the radio receiving a signal; generating a digital power level signal from the received signal; integrating the digital power level signal to generate a digital AGC adjust signal; generating a linearized digital receive adjust signal in response to one of the plurality of receive slope values and one of the plurality of receive offset values; converting the linearized digital receive adjust signal into an analog receive adjust signal, the analog receive adjust signal controlling the gain of the receive AGC amplifier; generating a linearized digital transmit adjust signal; and converting the linearized digital transmit adjust signal into an analog transmit adjust signal, the analog transmit adjust signal controlling the gain of the transmit AGC amplifier. - View Dependent Claims (14)
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Specification