Flash converters

The ultra fast analog to digital converters are called flash converters. They are also called simultaneous converters. Flash converters have two digital output lines. An analog circuit called comparator is used here. Comparator is always represented by a triangle symbol with two inputs and one output. When the voltage at the upper input is relatively positive with respect to the lower input, comparator output will be ‘1’. When the upper input is negative with respect to the lower input, comparator output will be ‘0’. Flash converters of many varieties exist. Flash converters of various sizes and different speeds are available. The latest ultra fast single-chip converters perform 8-bit conversions at a 100 million conversions per second rate. The major problem here is the requirement of very large number of comparators.