Correlated double sampling variable gain amplifier circuit for use in a digital camera

US7289145B2 · kind B2 · utility

Assignee

• CIRRUS LOGIC, INC. · US

Inventors

• Sandra M. Johnson · Kyle, US
• Shih-Chung Chao · Austin, US
• Nadi R. Itani · Austin, US
• Caiyi Wang · Austin, US
• Brannon Harris · Austin, US
• Ash Prabala · Austin, US
• Douglas R. Holberg · Wimberley, US
• Alan Wayne Hansford · Austin, US
• Syed Khalid Azim · Fremont, US
• David R. Welland · Austin, US

Key dates

• Filing date: May 1, 2006
• Grant date: Oct 30, 2007
• Expiry date: May 1, 2026

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N25/78
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

An image processor system for a charge coupled device (CCD) or CMOS imaging system includes a correlated double sample and variable gain (CDSVGA) circuit for receiving data from a CCD system and an automatic gain control (AGC) circuit which first controls gain by adjusting said CCD system and then for yet a higher gain level makes gain adjustments in said CDSVGA circuit AND a digital gain circuit to produce a combined target gain level. A processing system for an imager device includes a camera system for producing an imager signal, a correlated double sample (CDS) circuit for receiving data from an imager, a variable gain amplifier (VGA), an analog-to-digital converter (ADC) coupled to said CDS circuit, a digital gain circuit (DGC) coupled to said ADC, and an automatic gain control (AGC) circuit coupled to said DGC for controlling the CDS circuit and the DGC. The processing circuitry includes an analog front end and a digital signal processing system for capturing full motion video and outputting a CCIR 601 4:2:2 YCrCb video data output for presentation on a user selected display.