公开(公告)号：JPH11317666A

公开(公告)日：1999-11-16

申请号：JP1940999

申请日：1999-01-28

Applicant: IBM

Inventor： SADEEL MANISWAMY GOUDA ,  HYUN YONG SHIN ,  WONG HON-SUM P ,  PETER HONG KISHAO ,  JANGOUK YOUNG

IPC: H04N5/14 ,  H03M1/18 ,  H04N5/243

Abstract: PROBLEM TO BE SOLVED: To provide an automatic gain control circuit in which an automatic gain control function is completely executed in a digital area. SOLUTION: This digital automatic gain control circuit for an image sensor, which has an ADC 104 which converts an analog electric signal from an image sensor into a corresponding digital code is provided with a minimum/maximum detector 106, which decides minimum and maximum electric signal values from the digital code of the ADC 104 for each frame of an image. A filter 108 connected to the detector 106 suppresses the instantaneous change in the minimum and maximum electric signal values by filtering and gives filtered minimum and maximum values. A DAC 110 generates minimum and maximum analog reference voltages, which respectively correspond to the filtered minimum and maximum values and supplies them to the ADC 104 and they control an amplitude that is related to the digital code given from the ADC 104.