Time delay circuits: A quality criterion for delay variations versus frequency

This paper shows that the group delay of a delay circuit does not give sufficient information to predict the delay vs. frequency. A new criterion (f_φ=0) is proposed that characterizes the delay variations over a specified frequency range. The mathematical derivation of f_φ=0 for a single delay block and a cascade of delay blocks is shown. As examples the criterion is applied to the design of an RC and LC delay block. Delay predictions based on f_φ=0 compared with simulation results, showing reasonable agreement.