Design of low-frequency constant time delay lines

A TIME DELAY LINE for low-frequency signals normally consists of a cascade connection of inductance-capacitance networks employing lumped constants. There are a number of types of low pass sections that are particularly useful where constant delay of signals ranging in frequency from near zero to some arbitrary upper limit, is required. Several of these, such as the M-derived and the bridged-T, have received considerable attention and have been discussed.¹ However, one whose delay characteristic and simplicity of construction compares very favorably with others is the Pierce unsymmetrical section.