New strategies for fast ADC circuits

A new strategy of successive approximation for fast analog-to-digital converter (ADC) circuits is discussed. A 4-b converter of one-cycle conversion time is first described. The scheme is then modified for flash conversion. The use of a 4-b flash converter in multiplex mode is shown to result in an 8-b converter requiring half-cycle conversion time. The bit subrangeable flash ADC is presented as an attractive proposal. This scheme essentially requires only two major components per bit and uses n identical circuits in cascade for n-b conversion