Input charge distribution converters come in many flavors, including SAR, Pipeline, and Delta-sigma topologies. The most popular and versatile Analog-to-Digital Converter (ADC) has a Successive Approximation Register (SAR) topology. The modern SAR converters use an input capacitive array to capture the input signal. For optimum performance, these types of SAR-ADCs require the correct front-end buffer and passive filter. This class details the justification for the buffer amplifier and input filter to the SAR-ADC along with an analytical approach to selecting the filter components and op amp characteristics.