Four‐channel GaAs multifunction chips with bottom RF interface for Ka‐band SATCOM antennas

Abstract

Receiver and transmitter monolithic microwave integrated circuit (MMIC) multifunction chips (MFCs) for active phased‐array antennas for Ka‐band satellite communication (SATCOM) terminals have been designed and fabricated using a 0.15‐μm GaAs pseudomorphic high‐electron mobility transistor (pHEMT) process. The MFCs consist of four‐channel radio frequency (RF) paths and a 4:1 combiner. Each channel provides several functions such as signal amplification, 6‐bit phase shifting, and 5‐bit attenuation with a 44‐bit serial‐to‐parallel converter (SPC). RF pads are implemented on the bottom side of the chip to remove the parasitic inductance induced by wire bonding. The area of the fabricated chips is 5.2 mm × 4.2 mm. The receiver chip exhibits a gain of 18 dB and a noise figure of 2.0 dB over a frequency range from 17 GHz to 21 GHz with a low direct current (DC) power of 0.36 W. The transmitter chip provides a gain of 20 dB and a 1‐dB gain compression point (P1dB) of 18.4 dBm over a frequency range from 28 GHz to 31 GHz with a low DC power of 0.85 W. The P1dB can be increased to 20.6 dBm at a higher bias of +4.5 V.