Here is an example of a typical application for ADI’s low charge injection and low leakage parts. The PLC output Stage uses a Sample-and-hold per channel  architecture with switched capacitors and buffers as sample-and-hold amplifiers to store selected output samples from a single high-performance DAC. The samples are switched among the various capacitors, using an analog multiplexer. Since the accuracy of the system is determined by the droop rate of the capacitors, the multiplexer needs to have very low charge injection and leakage current.