ABSTRACT
The function of sample and hold is to freeze the analog input signal for discrete-time sampled-data processing. It is the basic functional block for all switched-capacitor filters and data converters. Digital-to-analog converters, called decoders in communications terms, are devices through which digital processors communicate with the outside analog world. The jitter effect is prominent in all sampled-data processing, such as analog-to-digital and digital-to-analog conversions. The clock jitter greatly affects the noise performance of the sampled signal and is the most critical factor to consider when sampling and reconstructing high-frequency components. If the input common-mode shift becomes an issue, dummy transistors of half the size can be connected and driven using the inverted sampling clock to absorb the charge from the top-plate switch. After sampling, the charge injection and feed-through from the top-plate switches lower the input common mode. In addition to the charge injection and feed-through error just discussed, the nonlinearity of the sampling switch greatly affects the sampling accuracy.
