Power-switched sample-and-hold provides accurate analog inputs for ADC in low-power system

This paper describes the design of a low-power, two-channel, 12-bit, data acquisition system with a conversion rate of 240 samples per second on each of the two input channels. Power switching the sample-and-hold module resulted in a power reduction of 140 mW compared with a continuously powered system. The total power consumption for the system was 102 mW. Preliminary information is given about the warm-up characteristics of a variety of operational amplifiers and a commercial sample-and-hold module; this is not available in the standard data books.