Question

Draw the block diagram of an eight-bit Successive Approximation Converter (Analog to
Digital converter), and explain its operation by considering the expected output digital
sequence for a given input analog signal as 01100101.

Answer 1

Explanation:

A successive approximation A/D converter consists of a comparator, a successive approximation register (SAR), output latches, and a D/A converter.

The main part of the circuit is the 8-bit SAR, whose output is given to an 8-bit D/A converter. The analog output Va of the D/A converter is then compared to an analog signal Vin by the comparator. The output of the comparator is a serial data input to the SAR. Till the digital output (8 bits) of the SAR is equivalent to the analog input Vin, the SAR adjusts itself. The 8-bit latch at the end of conversation holds onto the resultant digital data output.