A 6–18-GHz GaAs Multifunction Chip With 8-bit True Time Delay and 7-bit Amplitude Control

This paper presents a monolithic microwave integrated circuit multifunction chip implemented using a 0.25-μm gallium arsenide pseudomorphic high-electron-mobility transistor process for use in a phased array jammer transmitter. This chip, which operates in the frequency range of 6-18 GHz, provides several functions including 8-bit true time delay (TTD), 7-bit attenuation, wideband amplification, and digital serial-toparallel conversion for 15-bit control. The TTD and attenuation coverage are 255 ps with a step of 1 ps and 31.75 dB with a step of 0.25 dB, respectively. The TTD employing an artificial transmission line configuration demonstrates a root-mean-square delay error of less than 1.7 ps in the operating frequency range. The chip has a compact size of 4 mm × 5 mm and exhibits a typical gain of 12 dB and an output P1dB of 16.5 dBm over a frequency range of 6-18 GHz.