A Millimeter-Wave (40-45 GHz) 16-Element Phased-Array Transmitter in 0.18-μm SiGe BiCMOS Technology

This paper demonstrates a 16-element phased-array transmitter in a standard 0.18-mu m SiGe BiCMOS technology for Q-band satellite applications. The transmitter array is based on the All-RF architecture with 4-bit RF phase shifters and a corporate-feed network. A 1:2 active divider and two 1:8 passive tee-junction dividers constitute the corporate-feed network, and three-dimensional shielded transmission-lines are used for the passive divider to minimize area. All signals are processed differentially inside the chip except for the input and output interfaces. The phased-array transmitter results in a 12.5 dB of average power gain per channel at 42.5 GHz with a 3-dB gain bandwidth of 39.9-45.6 GHz. The RMS gain variation is < 1.3 dB and the RMS phase variation is < 8.8 degrees for all 4-bit phase states at 35-50 GHz. The measured input and output return losses are < - 10 dB at 36.6-50 GHz, and < - 10 dB at 37.6-50 GHz, respectively. The measured peak-to-peak group delay variation is +/- 20 ps at 40-45 GHz. The output P-1dB is -5 +/- 1.5 dBm and the maximum saturated output power is -2.5 +/- 1.5 dBm per channel at 42.5 GHz. The transmitter shows < 1.8 dB of RMS gain mismatch and < 7 degrees of RMS phase mismatch between the 16 different channels over all phase states. A -30 dB worst-case port-to-port coupling is measured between adjacent channels at 30-50 GHz, and the measured RMS gain and phase disturbances due to the inter-channel coupling are < 0.15 dB and < 1 degrees, respectively, at 35-50 GHz. All measurements are obtained without any on-chip calibration. The chip consumes 720 mA from a 5 V supply voltage and the chip size is 2.6 x 3.2 mm(2).