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Open Access Publications from the University of California

Millimeter-wave Wafer-Scale Phased Arrays and Wireless Communication Circuits and Systems in SiGe and CMOS Technology


This thesis presents a W-band wafer-scale phased array transmitter with high efficiency on-chip antennas. The 4x4 phased array is based on an RF beamforming architecture with an equiphase distribution network and 2-bit phase shifters placed in every element. The differential on-chip antennas are implemented using a 100 um thick quartz superstrate and have an efficiency of ̃45% at 110 GHz. The use of electromagnetically coupled antenna leads to wafer- scale phased array concept with simple integration method. The phased array transmitter is implemented in 0.18 [mu]m SiGe BiCMOS process, and the measurement shows an array gain of 26.5 dB, pattern directivity of 17.0 dBi, maximum EIRP of 23-25 dBm at 108-114 GHz. The direct pattern measurement from the phased array transmitter shows beam steering capabilities up to plus/minus ±30° in two orthogonal directions. This is the first demonstration of wafer-scale phased array in silicon technology. Millimeter -wave circuit components in 45nm SOI CMOS technology are also presented. Transmission-line based D-band common- source and cascode amplifers are designed with the peak gain of 8.7 dB at 147 GHz and 6.1 dB at 171 GHz, respectively. The experimental characterization of the technology shows that on-chip passive elements has low- quality factor, and it can offset performance advantage of the active devices. A 60 GHz active phased shifter with quadrature all-pass filter shows -4 dB insertion gain with <1.5 dB RMS gain error and <10° RMS phase error. An analysis shows the asymmetric loading to the all-pass filter can induce more phase error, and the use of series resistor is used as a mitigation. Also, an OOK transmitter in 90nm CMOS technology is presented. The OOK transmitter consists of a 30 GHz VCO, a resistive coupler, a frequency doubler, an OOK modulator based on a cascode amplifier, and a medium power amplifier. A single-ended architecture results in simple low-power implementation of a transmitter, and an output OOK spectrum up to Gbps range is observed, demonstrating OOK modulation scheme is suitable for low-power point-to-point high data-rate communication link in millimeterwave frequencies

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