Abstract: A digital video system (2) is disclosed, in which an analog input video signal is sampled at an optimum sample phase (Pnc), and converted to a digital datastream for display. A phase-locked loop (12) generates a plurality of sample clock phases. One of the sample clock phases (Pnc) is applied to an analog-to-digital converter (10), which digitizes the analog input video signal accordingly. Phase alignment circuitry (20) is provided that includes three sample-and-hold circuits (22b, 22c, 22a) that sample the analog input video signal, in parallel with the analog-to-digital converter (10), at times before, at, and after the current sample clock phase used by the analog-to-digital converter (10). The earlier and later sampled voltages are compared against the current sampled voltages to generate difference voltages that are each compared against a threshold voltage (Vthr).

Abstract: A digital video system (2) is disclosed, in which an analog input video signal is sampled at an optimum sample phase (Pnc), and converted to a digital datastream for display. A phase-locked loop (12) generates a plurality of sample clock phases. One of the sample clock phases (Pnc) is applied to an analog-to-digital converter (10), which digitizes the analog input video signal accordingly. Phase alignment circuitry (20) is provided that includes three sample-and-hold circuits (22b, 22c, 22a) that sample the analog input video signal, in parallel with the analog-to-digital converter (10), at times before, at, and after the current sample clock phase used by the analog-to-digital converter (10). The earlier and later sampled voltages are compared against the current sampled voltages to generate difference voltages that are each compared against a threshold voltage (Vthr).