Abstract: This paper presents fully integrated X-band and Ka-band T/ R multifunctional chips (MFCs) using 0. 13 滋m SiGe BiCMOS technology. 5-bit phase shifter, low noise amplifier, power amplifier, and T/ R control switches are inte- grated in a single chip. Via adopting distributed structures in small signal amplifiers and stacked structure in power amplifiers during MFCs'design, our proposed two MFCs both have wideband performance with high gain and high output power. The X-band MFC achieves receive/ transmit gain of 25/22 dB and transmit output P-1dB of 28 dBm; the Ka-band MFC achieves receive/ transmit gain of 17/14 dB and transmit output P-1dB of 20. 5 dBm. With competitive technical targets compared with state-of-the-arts, the proposed X-band and Ka-band MFCs using silicon-based technology provide good conditions for the min- iaturization and cost down of phased array systems.