ELECTRONIC SAMPLING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a sampling circuit which measures the difference between two or more analog signals by using an analog-to-digital converter whose costs are lower and whose number of bits is smaller. SOLUTION: A linear lamp at a square-wave voltage is applied to a first electrode which is immersed in a solution. A current which is obtained by an adjacent electrode is converted into a voltage for a sampling operation. A pair of sample-and-hold circuits 40, 42 store signals which are sampled in the peak of square-wave pulses and in an adjacent valley. An analog difference circuit 44 which follows subtracts two signals. A signal which is obtained as a result is converted into a digital code by an analog-to-digital converter 46 which is low-cost and whose number of bits is small, and it is stored on a microprocessor 48. A sampling process is repeated with reference to continuous square waves along the lamp.