Gain control in a communication channel
First Claim
1. An apparatus for gain control in a receiver, comprising:
- at least one frequency down-converter that receives at least one receiver channel signal and produces one or more baseband signal DC offset voltages in at least one baseband signal;
a level detector that performs the following;
monitors the at least one baseband signal to determine when the amplitude of the at least one baseband signal changes; and
upon determining that the amplitude of the at least one baseband signal has changed, generates first and second automatic gain control (AGC) signals;
a first AGC amplifier that receives said first AGC signal and amplifies the at least one baseband signal according to the first AGC signal;
a second AGC amplifier that receives said second AGC signal and amplifies the at least one receiver channel signal according to the second AGC signal;
the first and second AGC amplifiers that amplify the at least one baseband signal and the at least one receiver channel signal using the first and second AGC signals configured to reduce the one or more baseband signal DC offset voltages; and
a multiplier that receives the first automatic gain control (AGC) signal and outputs the second AGC signal, wherein said multiplier includes an operational amplifier, a first resistor and a second resistor arranged in a non-inverting amplifier configuration.
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Accused Products
Abstract
Methods and apparatuses for reducing DC offsets in a communication system are described. In a first aspect, a feedback loop circuit reduces DC offset in a wireless local area network (WLAN) receiver channel. The frequency response of the feedback loop circuit can be variable. In a second aspect, a circuit provides gain control in a WLAN receiver channel. The stored DC offset is subtracted from the receiver channel. First and second automatic gain control (AGC) amplifiers are coupled in respective portions of the receiver channel. In a third aspect, a feedback loop circuit reduces DC offset in a WLAN receiver channel. The feedback loop circuit includes a storage element that samples and stores receiver channel DC offset. The loop is opened, and the DC offset stored in the storage element is subtracted from the receiver channel. Circuits for monitoring DC offset, and for providing control signals for controlling the frequency response of the DC offset reducing circuits are also provided.
885 Citations
17 Claims
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1. An apparatus for gain control in a receiver, comprising:
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at least one frequency down-converter that receives at least one receiver channel signal and produces one or more baseband signal DC offset voltages in at least one baseband signal; a level detector that performs the following; monitors the at least one baseband signal to determine when the amplitude of the at least one baseband signal changes; and upon determining that the amplitude of the at least one baseband signal has changed, generates first and second automatic gain control (AGC) signals; a first AGC amplifier that receives said first AGC signal and amplifies the at least one baseband signal according to the first AGC signal; a second AGC amplifier that receives said second AGC signal and amplifies the at least one receiver channel signal according to the second AGC signal; the first and second AGC amplifiers that amplify the at least one baseband signal and the at least one receiver channel signal using the first and second AGC signals configured to reduce the one or more baseband signal DC offset voltages; and a multiplier that receives the first automatic gain control (AGC) signal and outputs the second AGC signal, wherein said multiplier includes an operational amplifier, a first resistor and a second resistor arranged in a non-inverting amplifier configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for gain control in a receiver, comprising the steps for :
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using at least one frequency down-converter that receives at least one receiver channel signal and produces one or more baseband signal DC offset voltages in at least one baseband signal; monitoring the at least one baseband signal to determine when the amplitude of the baseband signal changes; upon determining that the amplitude of the at least one baseband signal has changed, generating first and second automatic gain control (AGC) signals; amplifying the at least one receiver channel according to the second AGC signal; amplifying the at least one baseband signal according to the first AGC signal; reducing the one or more baseband signal DC offset voltages by amplifying the at least one baseband signal and the at least one receiver channel signal using the first and second AGC signals; and receiving the first automatic gain control (AGC) signal at a multiplier and outputting the second AGC signal, wherein said multiplier includes an operational amplifier, a first resistor and a second resistor arranged in a non-inverting amplifier configuration. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification