This paper presents a Ku-band monolithic multifunction transmitter and receiver chipset fabricated in 0.25-μm GaAs pseudomorphic high-electron mobility transistor technology. The chipset achieves a high level of integration, including a 4-bit 360° digital phase shifter, 5-bit 15.5-dB digital attenuator, amplifier and 9-bit digital serial-to-parallel converter for digital circuit control. Since the multifunction chipset includes a medium power amplifier and a low-noise amplifier, it features high P1dB and low noise figures over the full Ku-band frequencies. The multifunction transmitter shows a peak gain of 16.5 dB with output P1dB of 19.2 dBm at 15 GHz. The multifunction receiver shows a peak gain of 17.3 dB with noise figure of 2.5 dB at 15 GHz. The attenuation range is 15.5 dB with a step of 0.5 dB and the phase shift range is 360° with a step of 22.5°. Each chip area of the transmitter and receiver is 4.2 × 2.8 mm2.