True Time Delay line RFIC for X-band Timed Array Radars

In this paper, a novel design of RFIC-based 4-bit True Time Delay (TTD) line circuit at X-band (8–12 GHz) is presented for wideband Timed Array Radar application. The designed TTD line circuit is configured using eight numbers of 100 picoseconds delay elements along with distributed switching network to offer a maximum time delay of 800 picoseconds. The circuit is implemented in a compact size of 25 mm
²
using bulk 65 nanometer CMOS technology. The size of switches and characteristic impedance of the transmission lines are scaled optimally for low insertion loss variation across different delay states while maintaining flat delay performance over a wide bandwidth. The simulated circuit demonstrated input and output return loss of better than 10 dB, insertion loss of 13.5±1 dB, and group delay variation of ±6 picoseconds across 4 GHz bandwidth.