Latch circuit, double data rate ring counter based on the latch circuit, hybrid counting device, analog-digital converting device, and cmos image sensor

Abstract

Disclosed are a latch circuit receiving a negative output of a next stage latch circuit as a feedback input, a double data rate (DDR) ring counter based on the latch circuit to perform DDR counting of pulse periods and reduce the number of toggles, a hybrid counting device counting lower-bit portion by using the latch-based DDR ring counter and upper-bit portion by using a binary counter, and an analog-to-digital converting device and a CMOS image sensor employing the hybrid counting device. A double data rate ring counter may include a plurality of latches coupled in a ring type. The plurality of latches may include positive-edge-triggered latches and negative-edge-triggered latches arranged alternately. A current stage latch receives an output of a previous latch stage to shift to a next latch stage according to a counter clock, receives an output of the next latch stage to check a data shift to the next latch stage, and falls to a low level if the data shift is checked.