Method and apparatus for reducing DC offsets in a communication system

• US 20070086548A1
• Filed: 02/17/2006
• Published: 04/19/2007
• Est. Priority Date: 11/09/2001
• Status: Active Grant

• Current Assignee: ParkerVision, Inc.
• Original Assignee: ParkerVision, Inc.
• Inventors: Brown, Kevin, Sorrells, David, Rawlins, Michael, Rawlins, Gregory
• Granted Patent: US 7,653,158 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H03G 3/20 Automatic control H03G3/005 takes precedence; combined with volume compression or expansion H03G7/00
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

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.

Claims

1-41. -41. (canceled)

42. An apparatus for gain control in a communication channel, comprising:

a multiplier that receives a first automatic gain control (AGC) signal and outputs a second AGC signal;

a first AGC amplifier that receives said first AGC signal; and

a second AGC amplifier that receives said second AGC signal.

50. A method for gain control in a communication channel, comprising the steps of:

(1) multiplying a first automatic gain control (AGC) signal by an amount to generate a second AGC signal;

(2) providing the first AGC signal to a AGC amplifier; and

(3) providing the second AGC signal to a second AGC amplifier.