Bit synchronizer

Abstract

A bit synchronizer for the interpretation of a bit data stream received in a receiver when strobed by an isochronous or plesiochronous clock signal which lies in the receiver time domain is disclosed. This is achieved by alternate activation and deactivation of a first and a second phase aligner respectively, based on monitoring a delay controlled voltage of the active phase aligner. These phase aligners each utilizes differential delay lines which are comprised of differential delay elements, which in turn are comprised of pairs of inverting devices, where both devices of each pair have a controllable delay for positive edges and a pulse form restoring function for negative edges, alternatively a controllable delay for negative edges and a pulse form restoring function for positive edges. Because each DDE is constructed symmetrically, feedback from the outputs Q and Q on INV2 can be easily effected to the inputs FB and FB on INV1, and from the outputs Q and Q on INV1 in a delay element can be readily fed back to the inputs FB and FB respectively on INV2 in the preceding delay element. Because the feedback route quickly changes the ramp edge to full logic level as soon as the threshold voltage has been reached in the inverting device, the preceding stage is prepared for the restoring function that it will have for the next data edge, thereby avoiding interference effects.