Signal conversion circuit and fingerprint identification system

A fingerprint identification system, comprising:

• a pixel array circuit, configured to receive a contact of a finger, and convert a capacitance formed between the pixel array circuit and the finger into a pixel output signal;
• a signal conversion circuit, connected to the pixel array circuit, and configured to generate a first digital signal according to a first analog signal, wherein the signal conversion circuit comprises:
• a comparator, comprising:
• a first input terminal, configured to receive the first analog signal;
• a second input terminal connected to a reference voltage generator, and configured to receive a reference voltage;
• an output terminal, configured to output a second digital signal;
• a counter connected to the output terminal, and configured to generate a first digital signal;
• and
• a fingerprint judging module, connected to the signal conversion circuit, and configured to judge, according to the first digital signal, whether the pixel output signal corresponds to a finger ridge or a finger valley.