An X-Band High-Accuracy GaAs Multifunction Chip With Amplitude and Phase Control

This paper presents a high-accuracy multifunction chip (MFC) with amplitude and phase control in X-band. The MFC is designed with a common leg structure and incorporates a 6-bit attenuator (ATT), a 6-bit phase shifter (PS), two gain compensation amplifiers (GCAs), three single pole double throw switches (SPDTs), and fourteen logic control circuits. The interstage matching networks (IMNs) are inserted to compensate for the insertion phase and attenuation changes from the design due to the mismatches occurring when cascading the separately designed PS and ATT blocks. The receive and transmit modes switching is achieved by using four SPDTs. In addition, the resistance feedback is used in GCAs to compensate for passive losses and provide gain to the MFC. The proposed MFC is fabricated in 0.15- $\mu \text{m}$ GaAs pseudomorphic high-electron-mobility transistor (pHEMT) process. In the range of 8–11 GHz, the measured maximum root-mean-square (RMS) amplitude error of the MFC is less than 0.28 dB, and the maximum RMS phase error is less than 3.3°. Moreover, the MFC is achieved with a size of 4.3 mm $\times2.85$ mm. Excellent performance and compact size make the MFC great potential in spaceborne phased array applications.