Abstract: Aiming at the problem that the output of general measuring bridge circuit is analog signal，a measuring bridge circuit with analog-to-digital conversion function applying digital potentiometer is proposed． The circuit is composed of a digital potentiometer，a microprocessor and a voltage comparator． A conversion rate of 226 ～ 926 μs and an error less than 0． 15% are realized． The circuit can adjust balance automatically，and the digital value of variable resistor in bridge circuit or the digital of signal to be surveyed can be measured and output in real time． The circuit expended the function of bridge circuit，and eliminated the A/D conversion chip in the bridge circuit system and simplified the structure of circuit．

Key words: digital potentiometer, bridge circuit, voltage comparator, analogue-to-digital ( A/D)