Parallel analog-to-digital converter

摘要

An analog signal is converted into an n bit digital signal by n comparator circuits which compare the analog input to 2n-1 reference inputs. Each comparator output alternates as the analog signal increases through the reference levels. Logic circuitry including n-1 exclusive-OR gates decodes the comparator outputs into an n bit code. A comparator circuit for comparing the analog input signal with each of several reference levels and providing an alternating output includes a pair of differential input transistors and a current sink transistor associated with each reference level. The collectors of the differential transistor pairs are cross coupled to two output resistors which are connected to a differential exclusive-OR gate. A latching circuit is operable to latch the comparator output when the comparator is in other than the comparing mode.