Abstract:

An X/Ku-band bi-directional True-time delay is presented in 0.25 μm GaAs pHEMT E/D technology.The bi-directional operation is realized by adding two-way selecting switches to the new trombone structure,and it has the advantage of low insertion loss variation among different delay states.Fourth-order and second-order inductive coupled all-pass networks are adopted to form two delay lines.The delay differences are controlled by selecting the delay path through the bi-directional active switches.The true-time delay operates with the bandwidth of 6~18 GHz,and it realizes a 3-bit delay with a minimal delay step of 15 ps and a maximal delay of 106 ps.Simulation results show insertion loss of 8.1~15 dB and the loss variation with delay is ±2 dB.The group delay Root-Mean-Square error less than 10 ps and return loss more than 15 dB are implemented with the chip size of 1.91 mm².The direct current consumption is 110 mW and the input P1dB is more than 7 dBm.

Key words: time delay, delay circuit, gallium arsenide, all-pass filters, low loss variation with delay