Single-detector automatic gain control circuit

Claim 2

An automatic gain control (AGC) circuit for a signal-processing module, the AGC circuit comprising: a variable attenuator adapted to vary the level of an input signal and apply the attenuated input signal to the signal-processing module, which generates an output signal; switched detector circuitry adapted to selectively detect either a sample of the input signal or a sample of the output signal; and a processor adapted to generate a control signal based on the detected input signal sample and the detected output signal sample, wherein the control signal adjusts the attenuation of the variable attenuator to compensate for a change in gain of the signal-processing module.

Claim 3

The invention of claim 1 , wherein: the signal-processing module is an RF amplifier; the variable attenuator is a voltage-controlled attenuator; and the AGC circuit further comprises a passive attenuator adapted to attenuate the output signal sample prior to application to the switched detector circuitry.

Claim 4

The invention of claim 1 , wherein the switched detector circuitry comprises: a first switch adapted to select either the input signal sample or the output signal sample; and a detector adapted to detect the selected sample from the first switch.

Claim 5

The invention of claim 3 , wherein the switched detector circuitry further comprises: a second switch connected to receive the detected sample from the detector; and first and second sample-and-hold (S&H) circuits connected to receive signals from the second switch and provide signals to the processor, wherein the second switch is adapted to provide the detected sample to one of the first and second S&H circuits, wherein: the first and second switches are synchronized to selectively provide the detected input signal sample to the first S&H circuit and the detected output signal sample to the second S&H circuit.

Claim 6

The invention of claim 3 , wherein the switched detector circuitry further comprises: a series input switch connected to apply the input signal sample to the first switch; and a series output switch connected to apply the output signal sample to the first switch, wherein the series input and output switches provide additional isolation between the input and output signal samples.

Claim 7

The invention of claim 3 , wherein: the first switch is further adapted to select a sample of a reflected signal from a load connected to an output of the AGC circuit for detection by the detector; and the processor is further adapted to monitor the detected reflected signal from the load.

Claim 8

The invention of claim 1 , wherein the AGC circuit further comprises a temperature sensor adapted to sense temperature of the signal-processing module, wherein the processor is adapted to control the variable attenuator based on the sensed temperature from the temperature sensor.

Claim 9

The invention of claim 1 , wherein the signal-processing module is part of the AGC circuit.

Claim 10

The invention of claim 1 , wherein: the signal-processing module is an RF amplifier; the variable attenuator is a voltage-controlled attenuator; the AGC circuit further comprises a passive attenuator adapted to attenuate the output signal sample prior to application to the switched detector circuitry; and the switched detector circuitry comprises: a first switch adapted to select either the input signal sample or the output signal sample; and a detector adapted to detect the selected sample from the first switch.

Claim 11

The invention of claim 9 , wherein the switched detector circuitry further comprises: a second switch connected to receive the detected sample from the detector; and first and second sample-and-hold (S&H) circuits connected to receive signals from the second switch and provide signals to the processor, wherein the second switch is adapted to provide the detected sample to one of the first and second S&H circuits, wherein: the first and second switches are synchronized to selectively provide the detected input signal sample to the first S&H circuit and the detected output signal sample to the second S&H circuit.

Claim 12

The invention of claim 9 , wherein the AGC circuit further comprises a temperature sensor adapted to sense temperature of the signal-processing module, wherein the processor is adapted to control the variable attenuator based on the sensed temperature from the temperature sensor.

Claim 13

The invention of claim 9 , wherein the signal-processing module is part of the AGC circuit.

Claim 14

The invention of claim 1 , wherein: the switched detector circuitry is further adapted to selectively detect a sample of a reflected signal from a load connected to an output of the AGC circuit; and the processor is further adapted to monitor the reflected signal from the load.

Claim 15

The invention of claim 13 , the AGC circuit further comprises: a sampling device adapted to sample the reflected signal from the load; and a passive attenuator adapted attenuate the reflected signal sample prior to application to the switched detector circuitry.

Claim 16

The invention of claim 14 , wherein the sampling device is a directional coupler.

Claim 17

The invention of claim 14 , wherein the sampling device is a circulator.

Claim 18

The invention of claim 1 , wherein: the signal-processing module is an RF amplifier; the variable attenuator is a voltage-controlled attenuator; the AGC circuit further comprises: a first passive attenuator adapted to attenuate the output signal sample prior to application to the switched detector circuitry; a sampling device adapted to sample the reflected signal from the load, wherein the sampling device is a directional coupler or a circulator; and a second passive attenuator adapted attenuate the reflected signal sample prior to application to the switched detector circuitry; and the switched detector circuitry comprises: a first switch adapted to select either the input signal sample, the output signal sample, or a sample of a reflected signal from a load connected to an output of the AGC circuit for detection by the detector; a detector adapted to detect the selected sample from the first switch and monitor the detected reflected signal from the load; a second switch connected to receive the detected sample from the detector; first, second, and third sample-and-hold (S&H) circuits connected to receive signals from the second switch and provide signals to the processor, wherein the second switch is adapted to provide the detected sample to one of the first, second, and third S&H circuits, wherein: the first and second switches are synchronized to selectively provide the detected input signal sample to the first S&H circuit, the detected output signal sample to the second S&H circuit, and the detected reflected signal sample to the third S&H circuit; a series input switch connected to apply the input signal sample to the first switch; and a series output switch connected to apply the output signal sample to the first switch, wherein the series input and output switches provide additional isolation between the input and output signal samples.

Claim 19

The invention of claim 17 , wherein the AGC circuit further comprises a temperature sensor adapted to sense temperature of the signal-processing module, wherein the processor is adapted to control the variable attenuator based on the sensed temperature from the temperature sensor.

Claim 20

The invention of claim 17 , wherein the signal-processing module is part of the AGC circuit.

Claim 21

An integrated circuit having an AGC circuit for a signal-processing module, the AGC circuit comprising: a variable attenuator adapted to attenuate an input signal and apply the attenuated input signal to the signal-processing module, which generates an output signal; switched detector circuitry adapted to selectively detect either a sample of the input signal or a sample of the output signal; and a processor adapted to generate a control signal based on the detected input signal sample and the detected output signal sample, wherein the control signal adjusts the attenuation of the variable attenuator to compensate for a change in gain of the signal-processing module.

Claim 22

An integrated circuit having an AGC circuit for a signal-processing module, the AGC circuit comprising: a variable attenuator adapted to attenuate an input signal and apply the attenuated input signal to the signal-processing module, which generates an output signal; switched detector circuitry adapted to selectively detect either a sample of the input signal or a sample of the output signal; and a processor adapted to generate a control signal based on the detected input signal sample and the detected output signal sample, wherein the control signal adjusts the attenuation of the variable attenuator to compensate for a change in gain of the signal-processing module.