Enhanced Wideband Active Load-Pull with a Vector Network Analyzer Using Modulated Excitations and Device Output Match Compensation

Angelotti, Alberto Maria; Gibiino, Gian Piero; Nielsen, Troels S.; Schreurs, Dominique; Santarelli, Alberto

doi:10.1109/ims30576.2020.9223947

Cited by 2 publications

(4 citation statements)

References 7 publications

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“…The estimation error is slightly larger for the case in which the source match is at a greater distance from the target load. These results, together with the ones reported in [9] for 80-MHz excitation BW and N = 237 tones, prove that the linear compensation procedure is able to correct for the effect of the DUT mismatch using very few measurements, and that it is directly applicable to hybrid load-pull scenarios.…”

Section: B Measurement Resultssupporting

confidence: 75%

“…With respect to the preliminary article in [9], this extended work further clarifies the proposed theoretical framework and validates the capabilities of the VNA-WALP method by reporting novel measurement results. The performance of the secants' method, used to set the required load profile, is compared to other known numerical algorithms.…”

supporting

confidence: 52%

“…As pointed out in the previous sections and in [9], the output match compensation procedure can be effectively used to initialize the secants' method in a well-conditioned way. The two starting points for the algorithm are then taken to be the zero-injection case (in which Γ 2 = Γ S2 ), and the injection resulting from the compensation procedure in Sec.…”

Section: Hybrid Methods Performancementioning

confidence: 99%

“…In conclusion, given the experimental results of Sec. V-B and the ones shown in [9], the LS output match measured using the multitone method is a suitable approximation to provide a first-step estimate of the solution to the WALP problem. On the other hand, more accurate models to describe the DUT LS output match behaviour could be adopted [8], possibly improving the pre-compensation.…”

Section: Estimation Of the Large-signal Output Matchmentioning

confidence: 98%

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Wideband Active Load–Pull by Device Output Match Compensation Using a Vector Network Analyzer

Angelotti

Gibiino

Nielsen

et al. 2021

IEEE Trans. Microwave Theory Techn.

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This work investigates wideband active load-pull (WALP) on microwave electron devices with a standard vector network analyzer (VNA), solely using calibrated frequencydomain relative measurements. Differently from the methods requiring full time-domain waveform acquisition capabilities, this approach removes any instantaneous bandwidth (BW) requirement, allowing to target modulated signals with arbitrarily large BWs. A VNA-based measurement setup is presented, and a novel mathematical framework is developed in order to enable the synthesis of an arbitrary wideband load profile using suitable numerical algorithms. A linear pre-compensation of the LS output match of the device, here implemented by different methods, is shown to significantly improve the speed and the stability of the basic secants' iterative method used to reach the target. Performance results, investigating the convergence properties of the approach and the effects of the setup dynamic range, are reported for a Gallium Nitride (GaN) high-electronmobility-transistor (HEMT) for up to 120-MHz output BW in the sub-6 GHz range.Index Terms-Active load-pull, modulated signals, power amplifiers, vector network analyzer, device characterization. I. INTRODUCTIONT HE ever-growing demand for high data rates in modern mobile communication standards, e.g., 5G, requires the operation of power amplifiers (PA) in radio frequency (RF) transmitters across extremely wide bandwidths (BWs), i.e., tens or hundreds of MHz. In this respect, novel characterization techniques are required to evaluate the behaviour of electron devices used in PA circuits under operating conditions that closely approximate typical telecom applications. Wideband active load-pull (WALP) has been proposed as a promising technique to characterize microwave transistors and to optimize PA performance using excitations that mimic typical communication standards [1]-[4]. The method allows to set, for a given device-under-test (DUT), a user-prescribed load reflection coefficient profile across a wide modulation BW at fundamental and harmonic frequencies. The approach, at the cost of increased complexity, overcomes the main disadvantages of traditional passive load-pull. WALP can provide full coverage of the Smith Chart compensating for insertion loss, and can extend the narrow relative BW due to delay

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