Abstract: An X-band multi-function chip(MFC) with phase and amplitude control is designed and fabricated in 0.5 μm GaAs pHEMT technology, which can significantly improve the integration of transmit/receive (T/R) radar module. The MFC consists of a 2-bit true time delay(TTD), a 6-bit digital phase shifter, a 6-bit digital attenuator and two drive amplifiers. In terms of architecture design, a 2-bit TTD is introduced at the first time to achieve wideband operation while lowering beam squinting, and realizing the independent control of amplitude, phase and time delay on a single chip. The high-low pass phase shifting network and switch-path-type attenuation topology are employed in order to achieve high-precision phase and amplitude performance. The measurement results show that the RMS phase and amplitude error of 64-state phase shifter is 3.5° and 0.3 dB max, the RMS amplitude and phase error of 64-state attenuator is less than 0.4 dB and 2.5°, and the delay error of 3-state TTD is less than 1.5 ps over the 8 GHz to 12 GHz frequency band. The chip size is 5.0 mm×3.5 mm including the test pads.