Design of Millimeter-Wave Phase Shifters and Power Combiners in CMOS Technology

• Author / Creator

  Shamsadini, Shila

• The bandwidth equipment for future high-data-rate wireless communication systems can only be met by development of these systems at millimeter wave frequencies and beyond because of bandwidth scarcity in crowded low GHz frequencies. In the millimeter wave spectrum, 60-GHz band offers 7-GHz of unlicensed bandwidth and relaxed maximum signal power constraints of 10 W. However, the signal attenuation caused by path loss in the band and the narrow beam width of the electromagnetic waves make the detection of the wireless signals particularly challenging. To compensate for the path losses, an electronically steered narrow beam is required to focus the signal power in the desired direction. The beam of a phased-array antenna can be electrically steered to the desired radiation direction by progressively varying the phase of the signals feeding the array elements. Phase shifters are required to produce the progressive shifts in phased-array systems. The low cost of CMOS technology as well as its high level of integration make the technology a great candidate for the design of highly complex phased-array operating at mm-wave frequencies. In this dissertation, we present novel structures of phase shifters, power combiners, and merged phase shifters and combiners for mm-wave phased-arrays in 65-nm CMOS process technology that either enhance their performance or lower their cost (reducing their chip areas).First, we describe a 60-GHz artificial transmission line phase shifter designed in 65-nm CMOS technology. To increase the phase shift range and preserve the matching over the entire phase shift range, the fixed series inductors in the standard line cell are substituted by tunable inductors. The required tunable inductors are constructed using a transformer with the transformer secondary loaded by a varactor. To verify the operation principle, the phase shifters, including one-, two- and three-cell, were manufactured. The experimental phase shift range is 45° for the one-cell, 92° for the two-cell, and 133° for the three-cell line shifters. These figures are nearly 80% larger than the corresponding phase shifts in the lines consisting of cells with fixed inductors. The input/output return loss is less than 10 dB for all cases over the entire phase shift range. The average insertion loss is 3.2 dB for one-cell, 5.6 dB for two-cell, and 7.8 dB for three-cell transmission line phase shifters. The proposed continuous phase shifter achieves the highest phase shift range per area among the millimeter-wave transmission line and switch-type phase shifters reported to date. Second, a 60-GHz power combiner is proposed based on a distributed amplifier topology, applicable in phased-array antenna systems. A multi-input single-output power combiner is constructed by removing the input transmission lines of a distributed amplifier, the input signal delays are equalized by adding input delay/matching networks so that the amplified input signals are added constructively at the combiner’s output. Fabricated in 65-nm CMOS process, the measured results show a maximum insertion loss of 1 dB, and input/output reflections losses of better than 12 dB over the entire band of 57-GHz to 64-GHz while consuming 67 mW (56 mA) from a 1.2 V DC supply.Finally, a circuit merging an LNA, a phase shifter, and a power combiner is introduced to reduce the chip area and package cost based on a distributed amplifier topology by removing the gate transmission line and connecting the individual inputs to phase array antenna elements. The proposed block consists of a common source stage at the input, a loaded line phase shifter/combiner, and an output amplifier stage. Each circuit has been designed and optimized at 60-GHz. The proposed block has been designed and simulated for two inputs and one output. The s-parameters were simulated between each input-output pair with port 1 and 2 as the inputs and port 3 as the output. The simulated insertion losses of S31 and S21 are +5 dB and +4 dB at 60-GHz and has a noise figure lower than 7 dB. The simulated input and output return losses of the structure are better than 12 dB over the entire 57-GHz to 64-GHz frequency band. This block achieves 900 phase shift coverage and consumes 75 mW and occupies only 0.16 mm2 of die area.

• Subjects / Keywords

  • Phase Shifter
  • mmWave
  • CMOS

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-amr7-te41

• License

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