10.8 A 4-Element 500MHz-Modulated-BW 40mW 6b 1GS/s Analog-Time-to-Digital-Converter-Enabled Spatial Signal Processor in 65nm CMOS

Ghaderi, Erfan; Puglisi, Chase; Bansal, Shrestha; Sk, Gupta

doi:10.1109/isscc19947.2020.9063106

Cited by 14 publications

(7 citation statements)

References 4 publications

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“…This significantly relaxes the design requirement of the SCA and the clock path for TTD-based beam-training. Larger delaybandwidth products can thus be realized using passive SCA whose performance will not be limited by the opamp feedback factor or time-based circuits as demonstrated in our recent work in [23]. Ongoing research is also investigating use of high-linearity and high-speed ring amplifiers [26] in the SCA.…”

Section: A Baseband Implementation Of Analog Ttd Front-endmentioning

confidence: 91%

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True-Time-Delay Arrays for Fast Beam Training in Wideband Millimeter-Wave Systems

Boljanovic¹,

Han²,

Lin³

et al. 2020

Preprint

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The best beam steering directions are estimated through beam training, which is one of the most important and challenging tasks in millimeter-wave and sub-terahertz communications. Novel array architectures and signal processing techniques are required to avoid prohibitive beam training overhead associated with large antenna arrays and narrow beams. In this work, we leverage recent developments in true-time-delay (TTD) arrays with large delay-bandwidth products to accelerate beam training using frequency-dependent probing beams. We propose and study two TTD architecture candidates, including analog and hybrid analog-digital arrays, that can facilitate beam training with only one wideband pilot. We also propose a suitable algorithm that requires a single pilot to achieve high-accuracy estimation of angle of arrival. The proposed array architectures are compared in terms of beam training requirements and performance, robustness to practical hardware impairments, and power consumption. The findings suggest that the analog and hybrid TTD arrays achieve a sub-degree beam alignment precision with 66% and 25% lower power consumption than a fully digital array, respectively. Our results yield important design trade-offs among the basic system parameters, power consumption, and accuracy of angle of arrival estimation in fast TTD beam training. Index Terms-True-time-delay array, array architecture, beam training, millimeter-wave communication, wideband systems I. INTRODUCTIONA BUNDANT spectrum at millimeter-wave (mmW) frequencies is seen as the key resource for providing high data rates in the fifth generation of cellular systems [1]. However, the use of mmW communication bands comes at the cost of less favorable propagation conditions [2]. Both the base station (BS) and user equipment (UE) are required to use large antenna arrays to achieve high beamforming (BF) gain and compensate for severe propagation loss. Beam pointing directions are estimated through beam training, a procedure that identifies the angle of arrival (AoA) and angle

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Section: A Baseband Implementation Of Analog Ttd Front-endmentioning

confidence: 91%

“…Further, limited delay range at RF is insufficient to achieve frequency dispersive beam training as proposed in this work. Recent advancement in TTD arrays with baseband delay elements and large delay range-to-resolution ratios [22], [23], improved the scalability and thus enabled the realization of fast beam training schemes with large arrays.…”

mentioning

confidence: 99%

True-Time-Delay Arrays for Fast Beam Training in Wideband Millimeter-Wave Systems

Boljanovic¹,

Han²,

Lin³

et al. 2020

Preprint

Self Cite

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“…For example, in [8], we can achieve up to 15 ns delay range with 5 ps resolution supporting 100 MHz signal bandwidth. This bandwidth was recently enhanced to 500 MHz in [9] leveraging the digital-friendly and technology-scalable time-based circuits. The SCA based implementation of the beamformer requires N R phases for sampling ({ϕ n } NR n=1 ) followed by addition (S) and reset (RST) phase, in an N R -element array.…”

Section: Efficient Implementation Of Ttd Arraymentioning

confidence: 99%

Design of Millimeter-Wave Single-Shot Beam Training for True-Time-Delay Array

Boljanovic

Han

Ghaderi

et al. 2020

2020 IEEE 21st International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

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Beam training is one of the most important and challenging tasks in millimeter-wave and sub-terahertz communications. Novel transceiver architectures and signal processing techniques are required to avoid prohibitive training overhead when large antenna arrays with narrow beams are used. In this work, we leverage recent developments in wide range true-timedelay (TTD) analog arrays and frequency dependent probing beams to accelerate beam training. We propose an algorithm that achieves high-accuracy angle of arrival estimation with a single training symbol. Further, the impact of TTD frontend impairments on beam training accuracy is investigated, including the impact of gain, phase, and delay errors. Lastly, the study on impairments and required specifications of resolution and range of analog delay taps are used to provide a design insight of energy efficient TTD array, which employs a novel architecture with discrete-time sampling based TTD elements.

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“…Our implementation offers several improvements over published true-time-delay beamforming solutions [5]- [9]. The proposed RF-resampling TTD method is the only one published, which scales the delays with f c .…”

Section: Introductionmentioning

confidence: 99%

A 0.6–4.0 GHz RF-Resampling Beamforming Receiver With Frequency-Scaling True-Time-Delays up to Three Carrier Cycles

Spoof

Zahra

Unnikrishnan

et al. 2020

IEEE Solid-State Circuits Lett.

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True-time-delays enable wideband analog and hybrid beamforming by mitigating the beam squint problem. This paper reports a true-time-delay beamforming receiver supporting delays up to three carrier-frequency cycles. The implementation is the first published work in which the delays scale with the carrier frequency. The scaling enables true-time-delays for large arrays at low-GHz frequencies where long delays are required due to λc/2 antenna spacing. The delays are implemented through delayed resampling of a passive mixer's discrete-time output. Driving the mixers with pulse-skipped local oscillator (LO) signals allows the delay range to exceed one carrier cycle. A polyphase receiver structure prevents aliasing of noise and unwanted tones caused by LO pulse-skipping. Our prototype implementation demonstrates squint-free beamforming for an 800 MHz instantaneous RF bandwidth. The proposed true-timedelay is efficient for large arrays since the power consumption per antenna is only 5-13 mW across the 0.6-4.0 GHz frequency range. The prototype was implemented in 28-nm FD-SOI CMOS, and the die area including bonding pads is only 1.2 mm 2 .

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10.8 A 4-Element 500MHz-Modulated-BW 40mW 6b 1GS/s Analog-Time-to-Digital-Converter-Enabled Spatial Signal Processor in 65nm CMOS

Cited by 14 publications

References 4 publications

True-Time-Delay Arrays for Fast Beam Training in Wideband Millimeter-Wave Systems

True-Time-Delay Arrays for Fast Beam Training in Wideband Millimeter-Wave Systems

Design of Millimeter-Wave Single-Shot Beam Training for True-Time-Delay Array

A 0.6–4.0 GHz RF-Resampling Beamforming Receiver With Frequency-Scaling True-Time-Delays up to Three Carrier Cycles

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