Abstract:
A new scheme for a fully-digital Clock and Data Recovery (CDR) circuit is proposed which combines immediate acquisition with a continuous frequency range. It uses a Time to Digital Converter (TDC) that measures the position on the time axis of the incoming data edges. This time information is passed to a decision block which extracts the clock and data information. A waveform generator is then used to reconstruct the original data along with the synchronized clock. A survey on TDCs is given followed by a comparison of the new CDR architecture with known topologies. A design example of a prototype TDC is presented with a wide operation range and adjustable time resolution.