Patent ID: 7733395

Claim:
A variable-gain amplifier circuit, for receiving and amplifying an image sensing signal, comprising: a first variable path and gain amplifier circuit, having a first variable gain amplifier (VGA), for making the signal at the output end to be the signal at the input end either being amplified by the first VGA or bypassing without being amplified by the first VGA according to a first control signal; a second variable path and gain amplifier circuit, having a second VGA, for making the signal at the output end to be the signal at the input end either being amplified by the second VGA or bypassing without being amplified by the second VGA according to a second control signal; and a controller coupled to the first and the second variable path and gain amplifier circuits, generating the first control signal and the second control signal according to a digital signal of an analog-to-digital converter, so as to control paths in the first and second variable path and gain amplifier circuits, wherein the output end of the variable-gain amplifier circuit is coupled to the analog-to-digital converter, and when the signal at the output end of the variable-gain amplifier circuit is the image sensing signal being amplified by the first VGA and the second VGA, the analog-to-digital converter reduces the resolution of the output digital signal.