A Simple DC to 110 GHz MMIC True Time Delay Line

A simple miniaturized ultra-wideband true time delay line (TTD) is demonstrated using Indium Phosphide (InP) MMIC technology. An unprecedented bandwidth from close to dc to beyond 110 GHz is measured. The TTD has around 200 ps delay, a maximum insertion loss of only ~4.5 dB at 110 GHz, and better than 15 dB return loss across the majority of the band. This configuration significantly reduces the chip size, weight and cost. It demonstrates that wideband large time delay line is viable for planar IC implementation. To the authors' knowledge, this is the widest bandwidth ever reported for MMIC true time delay lines with relatively large time delay and compact size.