Srinivas N Neti

US Patent:

6774942, Aug 10, 2004

Filed:

Aug 17, 2000

Appl. No.:

09/642613

Inventors:

Jose A. Salcedo - Livermore CA
Srinivas N. Neti - San Jose CA
Charles A. Rogers - San Jose CA

Assignee:

Exar Corporation - Fremont CA

International Classification:

H04N 964

US Classification:

348243, 348257

Abstract:

An improved offset correction circuit for an image digitizing system having a correlated double sample and hold circuit, a programmable gain amplifier and an analog-to-digital converter. The output of the analog-to-digital converter is provided to a dual offset correction circuit. The dual offset correction circuit provides both first and second correction values as feedback signals. In one embodiment, the first correction value is a coarse correction which is applied prior to amplification by the programmable gain amplifier. The second correction value is a fine correction offset which is applied as feedback after the programmable gain amplifier.