Effects of AC Response Imperfections in True-Time-Delay Lines

A true-time-delay line distorts wideband pulses and introduces errors if it has a nonlinear phase or a non-constant magnitude. In this brief, the energy of the error due to phase and magnitude deviations is analyzed. It is shown that the error energy is proportional to integral of the sum of squares of phase and magnitude deviations. This metric is used to draw design insights for equalizing the ac response non-idealities and to evaluate the efficacy of some of the active all-pass filter based true-time-delay lines reported in the literature. The proposed metric is shown to be a more reliable predictor of wideband pulse distortion than other measures that have been used in the literature.