3D Simultaneous Multi-Material Printed RF Signal Processing Wideband Tunable True Time Delay Circuit

A 3D printed wideband tunable RF signal processing true time delay (TTD) circuit is proposed from a wideband RF Hilbert transformer and tunable transmission line. The RF Hilbert transformer rotates the phase of the waveform with a constant slope across the wideband without magnitude distortion, and a tunable transmission line adds a configurable phase offset to the constant slope, thereby realizing a frequency-independent tunable TTD characteristic. A double ring with star link structure is developed to extend the bandwidth of RF Hilbert transformer. The proposed wideband TTD circuit is fabricated using additive manufacturing method capable of simultaneously printing conductive and dielectric layers. The measurement results align with theory and simulation, achieving a tunable delay range of approximately ±82ps with less than 2 dB transmission loss across a bandwidth of approximately 4 GHz.