An $S$ -Band GaAs Multifunction Chip for Transmit/Receive Modules

In this article, a highly integrated S-band prototype multifunction chip (MFC) featuring high integration level, bidirectional operation, reduced number of pads, and optimized power consumption is demonstrated with a GaAs 0.15-μm pHEMT technology. In order to pursue a high integration level, the MFC utilizes four amplifiers, two bidirectional mixers, and compact integrated passive filters. For the sake of power supply pads, the self-biasing technique is adopted with the onchip power-combining technique. As for the power consumption minimization, when the system voltage is constant, the current reuse technique is selected with optimized transistor size without degradation of the key specifications. The main function for the MFC is to provide double-conversion and gain amplification both in the transmission path and the receiving path on one chip. In transmit mode, the MFC achieves 0-dB gain and 7-dBm P_-1dB from 2.6 to 3.2 GHz. The obtained local oscillator (LO)-radio frequency (RF) isolation is better than 50 dB, and the intermediate frequency (IF)-RF isolation is 85 dB. In receive mode, it achieves -5-dB gain with <; 10-dB noise figure from 2.6 to 3.2 GHz. The measured LO-IF isolation is more than 65 dB, and the RF-IF isolation is more than 50 dB. The VDD of the MFC is 5 V. The fabricated MFC occupied 5 mm × 5 mm, which is the largest record area that the process can withstand.