A Millimeter-Wave Partially Overlapped Beamforming-MIMO Receiver: Theory, Design, and Implementation

2016

Next-generation mobile technology (5G) aims to provide an improved experience through higher data-rates, lower latency, and improved link robustness. Millimeter-wave phased arrays offer a path to support multiple users at high datarates using high-bandwidth directional links between the base station and mobile devices. To realize this vision, a phased-array-based pico-cell must support a large number of precisely controlled beams, yet be compact and power efficient. These system goals have significant mm-wave radio interface implications, including scalability of the RFIC+antenna-array solution, increase in the number of concurrent beams by supporting dual polarization, precise beam steering, and high output power without sacrificing TX power efficiency. Packaged Si-based phased arrays [1-3] with nonconcurrent dual-polarized TX and RX operation [2,3], concurrent dual-polarized RX operation [3] and multi-IC scaling [3,4] have been demonstrated. However, support for concurrent dual-po...

IEEE Circuits and Systems Magazine, 2019

Millimeter wave (mmW) communications is viewed as the key enabler of 5G cellular networks due to vast spectrum availability that could boost peak rate and capacity. Due to increased propagation loss in mmW band, transceivers with massive antenna array are required to meet a link budget, but their power consumption and cost become limiting factors for commercial systems. Radio designs based on hybrid digital and analog array architectures and the usage of radio frequency (RF) signal processing via phase shifters have emerged as potential solutions to improve radio energy efficiency and deliver performances close to the conventional digital antenna arrays. In this paper, we provide an overview of the state-ofthe-art mmW massive antenna array designs and comparison among three array architectures, namely digital array, partiallyconnected hybrid array (sub-array), and fully-connected hybrid array. The comparison of performance, power, and area for these three architectures is performed for three representative 5G downlink use cases, which cover a range of pre-beamforming signal-to-noise-ratios (SNR) and multiplexing regimes. This is the first study to comprehensively model and quantitatively analyze all design aspects and criteria including: 1) optimal linear precoder, 2) impact of quantization error in digital-to-analog converter (DAC) and phase shifters, 3) RF signal distribution network, 4) power and area estimation based on state-of-theart mmW circuits including baseband digital precoding, digital signal distribution network, high-speed DACs, oscillators, mixers, phase shifters, RF signal distribution network, and power amplifiers. Our simulation results show that the fully-digital array architecture is the most power and area efficient compared against optimized designs for sub-array and hybrid array architectures. Our analysis shows that digital array architecture benefits greatly from multiuser multiplexing. The analysis also reveals that sub-array architecture performance is limited by reduced beamforming gain due to array partitioning, while the system bottleneck of the fully-connected hybrid architecture is the excessively complicated and power hungry RF signal distribution network. I. INTRODUCTION M Illimeter-wave (mmW) communications is a promising technology for the future fifth-generation (5G) cellular network [1], [2]. In the US, the Federal Communications Commission (FCC) has voted to adopt a new Upper Microwave Flexible Use service in the licensed bands, namely 28GHz (27.5-28.35GHz band), 37GHz (37-38.6GHz band),

2010

A 0.12-μm SiGe phased-array Rx IC for beam-steered wireless communication in the 60-GHz band is described. It has 16 RF phase-shifting front-ends with 11° digital phase resolution and hybrid passive-active RF signal combining. It achieves 7.4-7.9 dB NF (not including 12-dB array gain) over the 4 IEEE channels. The IC has a double-conversion superheterodyne Rx core with a maximum of 72 dB of power gain in 1-dB steps, and the on-chip synthesizer achieves <; -90 dBc/Hz Rx phase noise at 1MHz offset. The IC draws 1.8 W at 2.7 V with a die area of 38 mm2. It has been packaged with 16 antennas in a 288-pin organic BGA and phased-array beamsteering has been demonstrated, along with 5+ Gb/s wireless links using 16-QAM OFDM.

IEEE Journal of Solid-State Circuits, 2000

This paper describes a low power and element-scalable 60 GHz 4-element phased array transceiver implemented in a standard 65 nm CMOS process. Using a 1.2 V supply, the array consumes 34 mW/element including LO synthesis and distribution. Energy and area efficiency are achieved by utilizing a baseband phase shifting architecture, holistic impedance optimization, and lumped-element based design. Each receiver (RX) element provides 24 dB of gain with an average noise figure (NF) of 6.8 dB while the total saturated output power of the transmitter (TX) is 4.5 dBm. The array achieves 360 of phase shifting range with a worst-case measured phase resolution of 6 bits (TX)/ 5 bits (RX) while maintaining amplitude variations less than 0.5 dB.

IEEE Transactions on Antennas and Propagation, 2013

Millimeter-wave wireless systems are emerging as a promising technology for meeting the exploding capacity requirements of wireless communication networks. Besides large bandwidths, small wavelengths at mm-wave lead to a high dimensional spatial signal space, that can be exploited for significant capacity gains through high dimensional multiple-input multiple-output (MIMO) techniques. In conventional MIMO approaches, optimal performance requires prohibitively high transceiver complexity. By combining the concept of beamspace MIMO communication with a hybrid analog-digital transceiver, Continuous Aperture Phased (CAP) MIMO achieves near-optimal performance with dramatically lower complexity. This paper presents a framework for physically-accurate computational modeling and analysis of CAP-MIMO, and reports measurement results on a DLAbased prototype for multi-mode line-of-sight communication. The model, based on a critically sampled system representation, is used to demonstrate the performance gains of CAP-MIMO over state-of-the-art designs at mm-wave. For example, a CAP-MIMO system can achieve a spectral efficiency of 10-20 bits/s/Hz with a 17-31dB power advantage over state-of-the-art, corresponding to a data rate of 10-200 Gbps with 1-10GHz system bandwidth. The model is refined to analyze critical sources of power loss in an actual multi-mode system. The prototype-based measurement results closely follow the theoretical predictions, validating CAP-MIMO theory, and illustrating the utility of the model.

Sensors (Basel, Switzerland), 2018

Owing to the rapid growth in wireless data traffic, millimeter-wave (mm-wave) communications have shown tremendous promise and are considered an attractive technique in fifth-generation (5G) wireless communication systems. However, to design robust communication systems, it is important to understand the channel dynamics with respect to space and time at these frequencies. Millimeter-wave signals are highly susceptible to blocking, and they have communication limitations owing to their poor signal attenuation compared with microwave signals. Therefore, by employing highly directional antennas, co-channel interference to or from other systems can be alleviated using line-of-sight (LOS) propagation. Because of the ability to shape, switch, or scan the propagating beam, phased arrays play an important role in advanced wireless communication systems. Beam-switching, beam-scanning, and multibeam arrays can be realized at mm-wave frequencies using analog or digital system architectures. T...

IEEE Journal of Solid-State Circuits, 2018

This paper presents a "fully-connected" hybrid beamforming receiver that independently weights each element in an antenna array prior to separate downconversion chains that output independent baseband streams. A receiver architecture is introduced which implements RF-domain complex-valued Cartesian-weighting, RF-domain combining and multi-stream heterodyne complex-quadrature downconversion. Each RF-domain Cartesian weight is implemented by a pair of 5bit digitally-controlled programmable gain amplifiers (PGA), whose outputs are combined with the weighted signals from other antennas prior to complex-quadrature downconversion. Signal combination is performed by a wideband small-footprint distributed active combiner. A 25-30 GHz hybrid beamforming receiver with eight antenna inputs and two baseband output streams is designed in 65 nm CMOS. In each antenna path, the receiver achieves 34 dB conversion gain, 7.3 dB minimum noise figure, and 5 GHz of RF bandwidth. The entire receiver consumes 340 mW (equivalent to 27.5 mW per antenna per stream) including low-noise amplification, RF-domain beamforming, multi-stream downconversion and LO generation and distribution circuitry. The receiver occupies 3.86 mm 2 excluding pads, equivalent to 0.36 mm 2 per antenna per stream. Single-element characterization results are presented, along with characterization of several spatial processing techniques including interference cancellation (20 dB peak-to-null for two elements), simultaneous two-stream reception, and adaptivecodebook-search based beam-acquisition.

—In this correspondence, we propose a dual-function hybrid beamforming architecture, where the antenna array is split into sub-arrays that are separated by a sufficiently large distance so that each sub-array experiences independent fading. The proposed architecture attains the dual-functions of beamforming and diversity. We then demonstrate that splitting the array into two sub-arrays provides the best performance in terms of the achievable rate as a benefit of the diversity gain obtained in addition to the beamforming gain. However, the performance starts depleting if the array is partitioned into more than two sub-arrays because of diminishing additional diversity gains, which fails to compensate for the beamforming gain erosion due to splitting the antenna arrays. Additionally, we analyze the so-called discrete Fourier transform-mutually unbiased bases (DFT-MUB) aided codebook invoked for the conceived design, which imposes an appealingly low complexity. Explicitly, we show that for the proposed dual-function sub-array-connected design, the DFT-MUB assisted codebook outperforms the state-of-the-art precoding benchmarks and performs close to the optimal precoding matrix.

2010 IEEE International Symposium on Phased Array Systems and Technology, 2010

This paper presents an all-passive, 4-element, phased-array beamformer based on a differential, reflectiontype phase shifter (RTPS) operating in the 60GHz band. The RTPS consists of a differential, vertically-coupled, coupledline hybrid and variable, parallel-LC, resonant, reflective loads, both of which enable low-loss millimeter-wave operation. The design considerations for a silicon-based implementation of all the beamformer elements are discussed in detail. In particular, the influence of the different RTPS components on its insertion loss is analyzed. The beamformer IC and a breakout of the RTPS are implemented using CMOS-only features of IBM's 8HP 0.13µm SiGe BiCMOS process, and employ areas of 2.1mm 2 and 0.33mm 2 , respectively, without probe pads. Differential s-parameter measurements at 60GHz show a phase-shift range greater than 150 o , insertion losses of 4-6.2dB in the RTPS and 14-16dB in the beamformer, and an isolation better than 35dB between adjacent beamformer channels. Measurements across temperature and process variations are also presented.

2017 IEEE Nordic Circuits and Systems Conference (NORCAS): NORCHIP and International Symposium of System-on-Chip (SoC), 2017

A four element, two channel Multiple-Input Multiple-Output (MIMO) phased array receiver at 15 GHz is designed and fabricated in 45nm CMOS SOI process. The receiver consists of two independent four-antenna phasedarrays for hybrid beamforming and MIMO processing in digital domain. Phase and amplitude control is based on RF IQ vector modulator (VM) at carrier frequency. Measured downconversion gain and noise figure (NF) of one path are 23 dB and 5.4dB, respectively, giving estimated 3.4 dB NF for the IC when simulated PCB and matching losses are taken into account. 1 dB compression and IIP3 points are −37 dBm and −28 dBm, respectively. One phased array consumes 486 mW DC power from 1.2V power supply. Total chip area is 5.69 mm2.