Analog image signal processing circuit for CMOS image sensor
View Patent ↗An image signal processing circuit for CMOS image sensor comprises a differential operational amplifier, input stage capacitors, and output stage capacitors. The input stage capacitors comprise a first positive input stage switching capacitor array and a first negative input stage switching capacitor array. The first positive input stage switching capacitor array is configured to input analog image signals, a control end of the first positive input stage switching capacitor array is connected to a color gain control signal end, and an output end of the first positive input stage switching capacitor array is coupled to a positive input end of the differential operational amplifier. The first negative input stage switching capacitor array is configured to input a reference level signal, a control end of the first negative input stage switching capacitor array is connected to the color gain control signal end, and an output end of the first negative input stage switching capacitor array is coupled to a negative input end of the differential operational amplifier. The output stage capacitors are connected between the output end and the input end of the differential operational amplifier. In the present invention, two or more control functions are implemented with a single circuit, therefore, with the imaging effects guaranteed, the circuit structure is simplified, the size of the CMOS image sensor chip is reduced, and thus the cost is reduced. The present invention meets the developing trend of product miniaturization.
1. An analog image signal processing circuit for CMOS image sensor, which comprises a differential operational amplifier configured to convert single-end analog image signals into differential signal output, with an output end of the differential operational amplifier coupled to an A/D converter;
wherein the analog image signal processing circuit for CMOS image sensor further comprises input stage capacitors and output stage capacitors, the input stage capacitors comprise a second positive input stage switching capacitor array and a second negative input stage switching capacitor array;
an input end of the second positive input stage switching capacitor array is configured to input analog image signals and a first offset voltage signal, and an output end of the second positive input stage switching capacitor array is coupled to a positive input end of the differential operational amplifier;
an input end of the second negative input stage switching capacitor array is configured to input a second offset voltage, and an output end of the second negative input stage switching capacitor array is coupled to a negative input end of the differential operational amplifier;
wherein the output stage capacitors comprise a positive output stage switching capacitor array and a negative output stage switching capacitor array, the positive output stage switching capacitor array is being coupled between a positive output end and the negative input end of the differential operational amplifier, the negative output stage switching capacitor array is being coupled between and negative output end and the positive input end of the differential operational amplifier; the control ends of the positive output stage switching capacitor array and the negative output stage switching capacitor array being coupled to an exposure gain control signal end;
wherein a control end of the second positive input stage switching capacitor array and a control end of the second negative input stage switching capacitor array are coupled to the exposure gain control signal end.
2. The processing circuit according to claim 1 , wherein the input stage capacitors further comprise a first positive input stage switching capacitor array and a first negative input stage switching capacitor array;
an input end of the first positive input stage switching capacitor array is configured to input analog image signals, a control end of the first positive input stage switching capacitor array is coupled to a color gain control signal end, and an output end of the first positive input stage switching capacitor array is coupled to the positive input end of the differential operational amplifier;
an input end of the first negative input stage switching capacitor array is configured to input a reference level, a control end of the first negative input stage switching capacitor array is coupled to the color gain control signal end, and an output end of the first negative input stage switching capacitor array is coupled to the negative input end of the differential operational amplifier.