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Analysis and Design of a Multiple-Input Multiple-output (MIMO) Transmitter in the 60 GHz Band with a Beam Steering Capability Using All-digital Phase-locked Loop Chip

Salarpour, Mahdi | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52176 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Farzaneh, Forouhar
  7. Abstract:
  8. Multiple-Input Multiple-Output (MIMO) communications at millimeter-wave (mm-wave) frequencies (e.g., in the 60 GHz band) is a modern technology recently considered for various applications, such as emerging 5G services for multi-user MIMO (MU-MIMO) and high-resolution frequency-modulated continuous wave (FMCW) MIMO radars to support multi-gigabit throughputs in short-range environments via spatial multiplexing-diversity. Nevertheless, the impairments of communication channels in this frequency band, including significant propagation loss and severe blockage effect, are quite challenging to allow an efficient communication link. Hence, beamforming/beam steering can play a crucial role in 60 GHz MIMO systems to overcome the destructive influences of the communication channel. In principle, beam steering is much more practical and advantageous at the transmitter side than at the receiver side. The beam steering operation yields considerable improvements in the channel budget and capacity of the MIMO communications. As mm-wave antenna arrays are directional with very narrow beams, the accuracy of beam steering is quite vital in ensuring suitable wireless communication.In this thesis, a paradigm of MIMO transmitter in the 60 GHz band is proposed to fulfil the required accuracy for mm-wave beam steering. To provide such accuracy, this MIMO architecture is formed upon an array of all-digital phase-locked loop (ADPLL)-based transmitter elements and antennas whereby each transmitter chain is dedicated and in close proximity to an individual antenna unit with half-wavelength inter-element spacing. Our proposed solution is compact and cost-effective with very low-loss mm-wave interconnects and supports high precision for phase tuning (needed for highly-accurate mm-wave beam steering) using digitally-intensive approaches. As a proof-of-concept, a MIMO transmitter demonstrator is designed and developed employing the available ADPLL integrated circuit (IC) chips realized in 65 nm CMOS technology for 57-63 GHz frequency range. The performance of beam steering is verified via MATLAB system modelling and the final implementable transmitter hardware is derived. Due to importance of amplitude-phase alignment calibration to meet the required digital beam steering accuracy, a calibration technique based on signal cancellation method is explored as both on-wafer calibration on fused silica substrate for the demonstrator and over-the-air calibration for the intended paradigm. The calibration performance is validated by an experimental setup and the ADPLL phase noise is discovered to impact on the phase-alignment accuracy significantly. Therefore, the ADPLL phase noise effects on the cancellation technique are investigated by both theoretical analysis (mathematical formulation) and numerical simulations. Based on those simulations, the appropriate ADPLL specifications are derived to meet the required phase noise profile for highly-accurate beam steering in order to realize the proposed 60 GHz MIMO transmitter
  9. Keywords:
  10. All Digital Phase Locked Loop ; Antenna Array ; 60 GHz Band ; Beam Steering ; Cancellation Method ; Millimeter Wave ; Multiple Input Multiple Output (MIMO)System ; Phase Noise

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