Signal gain determination circuit and signal gain determination method

A signal gain determination circuit for a sensing integration circuit, comprising:

• a first register configured to store a predetermined count;
• a second register configured to store a first count;
• wherein the sensing integration circuit generates the first count according to a first sensing signal during a first integration time;
• a digital comparator coupled to the first register and the second register, and configured to compare the first count with the predetermined count to generate a comparison result after the first integration time;
• a digital controller coupled to the digital comparator, and configured to determine a signal gain according to the comparison result so as to generate a control signal for indicating the signal gain to a signal amplifier of the sensing integration circuit;
• wherein the signal amplifier is configured to adjust the first sensing signal according to the signal gain to generate a second sensing signal, so that the sensing integration circuit is configured to generate a second count corresponding to the second sensing signal during a second integration time, and the second register is configured to store the second count after the second integration time;
• a third register coupled to the digital controller, and configured to store the signal gain;
• an arithmetic module coupled to the third register and the second register, and configured to generate an output count corresponding to the first sensing signal according to the second count and the signal gain after the second integration time;
• and
• a fourth register coupled to the arithmetic module, and configured to store the output count.