A Ku-Band Actively Coupled-Line True Time Delay

This article presents an integrated microwave true time delay (TTD) phase shifter with active amplitude control for wireless frontends. The phase control is based on distributed digital control of wave propagation in an artificial transmission line. We implement a chip prototype based on this concept in the TSMC 65 nm process. The measured group delay resolution is 0.28 ps with a loss variation of less than 1 dB. The active tuning enables up to 15 dB amplitude control and ≤ -27 dB of reverse isolation across the Ku-band. The proposed structure enables broadband linear delay control for multiband phased arrays.