Robert J Reeves

US Patent:

6785529, Aug 31, 2004

Filed:

May 29, 2002

Appl. No.:

10/157259

Inventors:

Steven C. Ciccarelli - Encinitas CA
Arun Raghupathy - San Diego CA
Robert Reeves - Escondido CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04B 100

US Classification:

455324, 455323, 455296, 455302

Abstract:

A compensation circuit to correct for mismatch in a quadrature receiver comprises first and second mixers to receive a radio frequency (RF) modulated signal. One mixer receives an I local oscillator signal while the second mixer receives a Q local oscillator signal wherein the I and Q local oscillators have frequencies that are substantially identical. The output of the first and second mixers are coupled to first and second filters, respectively, which generate the I and Q output signals, respectively. Inherent circuit mismatch generate gain and/or phase errors that result in mismatch in the I and Q output signals. A correction circuit automatically applies a correction factor to at least one of the I and Q output signals to correct the gain and/or phase error by applying a multiplication factor to at least one of the I and Q output signals to thereby generate a corrected signal. The correction factors must be determined on a unit by unit basis. Testing in the final stages of factory assembly may be used to determine the value of the correction factor.

US Patent:

7915954, Mar 29, 2011

Filed:

Nov 12, 2004

Appl. No.:

10/987360

Inventors:

Arun Raghupathy - San Diego CA, US
Puay Hoe See - San Diego CA, US
Gurkanwal Kamal Sahota - San Diego CA, US
Robert Reeves - Escondido CA, US
Paul E. Peterzell - Plantation FL, US

Assignee:

QUALCOMM, Incorporated - San Diego CA

International Classification:

H03F 3/68

US Classification:

330149, 330151, 375316

Abstract:

Methods and apparatus for amplifier AM and PM predistortion and autocalibration. AM and PM amplifier distortion can be corrected using predistortion. The AM and PM distortion characteristics of the amplifier are determined using an autocalibration technique. The amplifier characteristics can be stored in distinct look up tables. Alternatively, the inverse of the amplifier characteristics can be stored in distinct look up tables. Signals that are to be amplified are characterized in polar format having a phase component with a normalized magnitude and a magnitude component. The phase component can be predistorted by applying the inverse of the PM distortion characteristics to the signal. Similarly, the magnitude component can be predistorted by applying the inverse of the AM distortion characteristics to the signal. The predistorted phase component can be amplified using the previously characterized amplifier. The predistorted magnitude component can be used to set the gain of the previously characterized amplifier.