Free-Space Phased-Array Characterization and Calibration Using Code-Modulated Embedded Test

Hong, Zhangjie; Schönherr, Simon; Chauhan, Vikas; Floyd, Brian

doi:10.1109/mwsym.2019.8701098

Cited by 13 publications

(6 citation statements)

References 5 publications

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“…The chip also features circuitry for built-in-test technique called as Code Modulated Embedded Test, or CoMET [Gre16]. CoMET uses the code-modulated interferometry and BOCP codes to characterize and calibrate the phased array, and is a secondary contribution of this research [Gre16;Hon19]. This technique has been demonstrated for this particular 60 GHz phased array in [Gre18].…”

Section: Four-element Arraymentioning

confidence: 99%

“…CoMET, as given in [Hon19]. The phase shifters are also used to code-modulate the RF signals with balanced, orthogonal, binary (±1) 256-bit Walsh-Hadamard codes (easily achievable by a 0 • and 180 • phase shift).…”

Section: Code-modulation Data Acquisition and Processingmentioning

confidence: 99%

“…In CoMET, a far-field test signal is coupled into the array and the complex cross-correlations between elements are measured and used to extract gain and phase information per element. We use this technique to calibrate and equalize the response of the full array with antennas, with more information provided in [Hon19]. Fig.…”

Section: Calibration Of Arraymentioning

confidence: 99%

“…Fig. 4.10 shows the resulting "overthe-air" extracted gain from [Hon19] for our eight-element RX array attached to eight adjacent antenna elements after a CMI-based calibration. Here the antennas are oriented in a uniform linear array for demonstration purposes.…”

Section: Calibration Of Arraymentioning

confidence: 99%

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PhD Thesis on Code Modulated Interferometric Imaging System using Phased Arrays

Chauhan¹

2021

Preprint

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CHAUHAN, VIKAS. PhD Thesis on Code Modulated Interferometric Imaging System using Phased Arrays. (Under the direction of Brian A. Floyd.) This work presents techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These codemodulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Provided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations.Firstly, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array and a benchmarking of the code-modulated interferometer against traditional interferometer using simulation results and sensitivity analysis. Secondly, for the proof of concept with a prototype, we present a simple CMI system operating in the license-free 60-GHz band using a four-element phased-array receiver developed for IEEE 802.11ad (WiGig) and packaged with compact antenna structures. The four-element 60-GHz phased array chip is wire-bonded onto a Rogers-5880 substrate board with on-board slot antennas, and a single 60-GHz output is measured using a power detector. This scalar measurement is then demodulated to obtain the interferometric visibilities.The four-element phased array is thinned to obtain a 13-pixel image and the system is

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Section: Four-element Arraymentioning

confidence: 99%

Section: Code-modulation Data Acquisition and Processingmentioning

confidence: 99%

Section: Calibration Of Arraymentioning

confidence: 99%

Section: Calibration Of Arraymentioning

confidence: 99%

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PhD Thesis on Code Modulated Interferometric Imaging System using Phased Arrays

Chauhan¹

2021

Preprint

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“…Code-modulated embedded test (CoMET) is an alternative solution, proposed in [7], [8], [9], [10], which employs a scalar (i.e., power) detector to extract all elemental vectors in a parallel fashion. Each element's test signature is modulated using the existing phase shifters and then aggregated into a code-multiplexed response.…”

Section: Introductionmentioning

confidence: 99%

Code-Modulated Embedded Test and Calibration of Phased-Array Transceivers

Hong

Chauhan

Schönherr

et al. 2021

IEEE Trans. Microwave Theory Techn.

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We present methods for built-in test and calibration of phased arrays using code-modulated embedded test (CoMET). Our approach employs Cartesian modulation of test signals within each element using existing phase shifters, combining of these signals into an aggregate code-multiplexed response, downconversion and creation of code-modulated element-toelement "interference products" using a built-in power detector, demodulation of correlations from the digitized interference response, and extraction of amplitude and phase per element using an equation solver. Rotated-axis methodology is discussed for accurate extraction of phase near the original 0/90/180/270 degree axes. Our techniques are demonstrated at board level for both receive and transmit modes using an eight-element 8-16 GHz phased array constructed using ADAR1000 chips from ADI. At 6 GHz, CoMET-extracted gain and phase are accurate to within 0.2 dB and 3 • compared to network-analyzer measurements. We then employ CoMET in a calibration loop to determinate optimum control settings at 6 GHz, outside the 8-16 GHz band for which the array was designed. We achieve seven-bit phase resolution with equalized gain. The root-mean squared gain and phase errors are improved from 0.8 dB and 8 • before calibration to 0.1 dB and 1.7 • after calibration.Index Terms-code-modulated embedded test, CoMET, codemodulated interferometry, phased array, built-in self-test, calibration, phase shifter.

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Over-the-Air Phase Calibration Methods for 5G mmW Antenna Array Transceivers

Jokinen,

Kursu,

Tervo

et al. 2024

IEEE Access

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Calibration is essential to optimize the performance of any radio transceiver during its development and manufacturing processes. This paper proposes over-the-air (OTA) calibration methods based on measuring and calibrating the phases of phased array transceiver paths. The phase responses of each signal path with all phase shifter states were characterized using an OTA radio link in the transmission and reception modes. Scattering parameter measurements give amplitude and phase responses over the frequency range, which can be converted to the delay domain with the Fourier transform. In this paper, two new delay domain phase calibration methods are presented and compared with a previously presented frequency domain method. The best performance was achieved with the relative phase calibration method in the delay domain which uses all measurement data to find the calibration values. The other two methods, i.e., the absolute phase calibration method in the delay domain and in the frequency domain, use the average phase as the calibration value. OTA radiation pattern measurements from two prototype 5G millimeter wave transceivers were used to compare the RF performances of the calibration methods, and measurements were performed with a 100 MHz 5G new radio waveform. The radiation patterns were analyzed based on direction accuracy, power level, and side lobe level, to give a few examples. The transceiver units were calibrated using the three studied methods, and while having significantly different uncalibrated performances, after calibration, both transceivers were tuned to similar performance levels.

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Free-Space Phased-Array Characterization and Calibration Using Code-Modulated Embedded Test

Cited by 13 publications

References 5 publications

PhD Thesis on Code Modulated Interferometric Imaging System using Phased Arrays

PhD Thesis on Code Modulated Interferometric Imaging System using Phased Arrays

Code-Modulated Embedded Test and Calibration of Phased-Array Transceivers

Over-the-Air Phase Calibration Methods for 5G mmW Antenna Array Transceivers

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