1. A method of A/D conversion with feedback loop is worked out to increase A/D conversion resolution effectively. An application example is given.

2. This is referred to as analog-to-digital (A/D) conversion.

3. The analog residue can be further processed to increase the accuracy of the A/D conversion.

4. 17 The computer-aided spark voltage test system for working electrolyte is established with A/D conversion technology and sampling circuit.

5. A sensor output value S(n) is obtained by A/D conversion of the output from a sensor resistance converter circuit (14).

6. The A/D conversion circuit further includes a converter that is responsive to the variable attenuator and that converts analog input signals to digital output signals.