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arxiv: 2605.01683 · v1 · submitted 2026-05-03 · ⚛️ physics.app-ph

Recognition: unknown

Numerical Validation of a MOSFET-Based Control Circuit for High-Power Intelligent Reflecting Surfaces for Wireless Power Transfer Applications

Akise Kumashiro, Atsuko Nagata, Eisuke Omori, Gakuto Ichikawa, Hiroki Wakatsuchi, Kazuhiro Kizaki, Shunsuke Saruwatari

Authors on Pith no claims yet

Pith reviewed 2026-05-09 16:42 UTC · model grok-4.3

classification ⚛️ physics.app-ph
keywords intelligent reflecting surfacesMOSFET control circuitwireless power transferhigh-power operationreflection phase controlnonlinear impedancebeam steering2.4 GHz
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0 comments X

The pith

A back-to-back MOSFET circuit with capacitors lets IRS unit cells maintain 180-degree phase control at powers above 1 W.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that intelligent reflecting surfaces can be made to operate reliably in high-power wireless power transfer settings by replacing sensitive control elements with a MOSFET-based binary switch. Most IRS designs break down when induced currents exceed low levels because nonlinearity in the switches changes the reflection phase. The proposed circuit adds series and parallel capacitors to the back-to-back MOSFET pair so that impedance stays nearly constant between the ON and OFF states. Transmission-line analysis and nonlinear simulations confirm the phase difference remains close to 180 degrees up to 1.25 W per cell, and far-field patterns show that switching different cells steers the reflected beam.

Core claim

The central claim is that a MOSFET-based binary control circuit for 2.4 GHz IRS unit cells can withstand input powers exceeding 1 W while preserving an approximately 180-degree reflection phase difference between its two states. The design uses a back-to-back MOSFET topology augmented with series and parallel capacitors to suppress impedance variations caused by device nonlinearity. A transmission-line theoretical model is validated against full-wave electromagnetic co-simulations that incorporate nonlinear SPICE device models. Dynamic-range checks against rated current and phase difference confirm stable behavior up to 1.25 W, and supercell-level simulations demonstrate active beam steering

What carries the argument

Back-to-back MOSFET switching topology with series and parallel capacitors that holds reflection-phase difference near 180 degrees by limiting nonlinear impedance drift.

If this is right

  • IRS arrays can be deployed in wireless power transfer without per-cell power limits below 1 W.
  • Binary phase control remains usable for beam steering even when each cell receives more than 1 W.
  • Switching-pattern reconfiguration produces controllable far-field reflection angles at high power.
  • The transmission-line model plus nonlinear SPICE co-simulation accurately predicts circuit behavior up to 1.25 W.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same capacitor-compensated topology could be scaled to other frequencies by retuning the lumped elements.
  • Hardware prototypes would be needed to check whether thermal effects or packaging parasitics alter the simulated stability.
  • Similar compensation might allow other nonlinear RF switches to serve in high-power IRS applications.
  • Integration into full WPT systems would require verifying that the reflected beam still delivers usable power to a target receiver.

Load-bearing premise

The added capacitors and back-to-back MOSFET arrangement will keep impedance variations small enough that the reflection phase difference stays close to 180 degrees when input power exceeds 1 W.

What would settle it

Direct measurement of the reflected phase difference at 1.25 W input power showing a deviation larger than a few degrees from 180 degrees between ON and OFF states would disprove stable high-power operation.

Figures

Figures reproduced from arXiv: 2605.01683 by Akise Kumashiro, Atsuko Nagata, Eisuke Omori, Gakuto Ichikawa, Hiroki Wakatsuchi, Kazuhiro Kizaki, Shunsuke Saruwatari.

Figure 1
Figure 1. Figure 1: The conceptual image of the proposed IRS. (a) A conventional IRS operating only for small-signal wireless communications. (b) The proposed IRS operating for both small-signal wireless communications and high-power WPT. a surface, the electric charges induced on the metallic patches oscillate at a resonant frequency determined by the unit cell dimensions. By adjusting structural parameters and composite med… view at source ↗
Figure 2
Figure 2. Figure 2: Equivalent parameters of the MOSFET switching circuit extracted at 2.4 GHz as a function of the input voltage vin. (a) The MOSFET switching circuit. (b) The parallel resistance and (c) parallel capacitance for the ON and OFF states. 0 5 10 15 v in (V) 0 200 400 600 800 1000 iin (mA) ON OFF Pulse rating view at source ↗
Figure 3
Figure 3. Figure 3: Input current iin of the switching circuit as a function of the input voltage vin for the ON and OFF states, compared with the pulse-rated current of 680 mA. 4/17 view at source ↗
Figure 4
Figure 4. Figure 4: Proposed control circuit. (a) Circuit topology showing the series capacitance C1, parallel capacitance C2, and back-to-back MOSFET switching circuit. (b) Equivalent circuit model with the MOSFET represented as a parallel RC network. However, the improved robustness afforded by a large C2 comes at the cost of a reduced susceptance contrast ∆B between the ON and OFF states. The susceptance difference is defi… view at source ↗
Figure 5
Figure 5. Figure 5: Suppression of the impedance variation by the parallel capacitance C2. (a-f) Resistance and reactance of the control circuit as a function of C2 when (a,b) R ON, (c,d) C ON, and (e,f) C OFF are perturbed by ±40%. Solid curves (left axes) show Re(Zab) or Im(Zab) for the −40%, nominal, and +40% cases, whereas the red dotted curves (right axes) show the spread between the −40% and +40% cases. capacitance C1 m… view at source ↗
Figure 6
Figure 6. Figure 6: Susceptance difference ∆B between the ON and OFF states as a function of the series capacitance C1 for several values of C2. Parameter Value (mm) Unit cell period p 15.0 Gap width g 3.0 Substrate thickness h 3.04 Patch width w 12.0 view at source ↗
Figure 7
Figure 7. Figure 7: Unit cell with an embedded control circuit. (a) The periodic unit cell without the loaded circuit (inset) and its period p and gap g satisfying the resonance condition. (b) Equivalent circuit of the loaded unit cell, including C0, L0, Ladd, and the control circuit. Theoretical design of binary reflection phases The complete loaded unit cell is represented by a shunt-impedance-loaded transmission line in wh… view at source ↗
Figure 8
Figure 8. Figure 8: Co-simulated reflection phase ∠Γ versus input power Pin for Designs 1–3 in the (a) ON and (b) OFF states, compared with the theoretical target values. the effective resonance and alter the impedance matching condition. 0 0.5 1 1.5 Pin (W) 0.8 0.9 1 | OFF| 2 Design 1 (Simulation) Design 1 (Theory) Design 2 (Simulation) Design 2 (Theory) Design 3 (Simulation) Design 3 (Theory) (b) 0 0.5 1 1.5 Pin (W) 0 0.4 0… view at source ↗
Figure 9
Figure 9. Figure 9: Co-simulated and theoretical reflection magnitudes versus input power for Designs 1–3 in the (a) ON and (b) OFF states. Dynamic range evaluation The practical operating envelope of the proposed IRS is constrained from above by the maximum tolerable current in the MOSFET and from below by the minimum input power at which the binary reflection phase difference remains within an acceptable range. We evaluate … view at source ↗
Figure 10
Figure 10. Figure 10: Maximum current in the switching circuit as a function of input power for Designs 1–3 in the ON and OFF states, compared with the pulse-rated current of 680 mA. Design Limiting state Max. Pin (W) 1 ON 0.965 2 ON 1.108 3 ON 1.250 view at source ↗
Figure 11
Figure 11. Figure 11: Reflection phase difference ∆Φ between the ON and OFF states as a function of input power for Designs 1–3. (a, b) The results in (a) a linear scale and (b) a logarithmic scale. Dashed lines represent the acceptable range (180◦± 37◦ ). The shaded region at extremely low power levels indicates numerical instability in the SPICE model. Pattern xv (mm) yv (mm) zv (mm) xs (mm) ys (mm) zs (mm) xp (mm) 1 1100 11… view at source ↗
Figure 12
Figure 12. Figure 12: Supercell models. (a) The entire simulation setup. Supercell models with (b) Pattern 1, (c) Pattern 2, (d) Pattern 3 and (e) Pattern 4 of unit cells. The orange and blue cells represent the ON- and OFF-state unit cells, respectively. -90° -60° -30° 0° 30° 60° 90° 0 dB 10 dB 20 dB Pattern 1 Pattern 2 -90° -60° -30° 0° 30° 60° 90° 0 dB 10 dB 20 dB Pattern 3 Pattern 4 (a) (b) view at source ↗
Figure 13
Figure 13. Figure 13: Simulated far-field radiation patterns. (a, b) Results for (a) asymmetric and (b) symmetric supercells. The dashed lines represent the theoretical reflection angles. far-field patterns exhibit bilateral symmetry: the main lobes appear at equal angles on either side of the broadside direction. Both patterns again deviate from the theoretical angles, which can be attributed to the finite number of nonintege… view at source ↗
read the original abstract

Intelligent reflecting surfaces (IRSs) have attracted considerable attention because of their ability to dynamically control electromagnetic wave propagation. While most existing IRSs have been developed for low-power communication and sensing applications, their extension to high-power wireless power transfer (WPT) environments remains largely unexplored, as the high induced currents can damage or saturate the sensitive control elements, disrupting their tuning functionality. Here, we propose a metal-oxide-semiconductor field-effect transistor-based (MOSFET-based) binary control circuit for IRSs operating at 2.4 GHz that can withstand input power levels exceeding 1 W per unit cell. The control circuit employs a back-to-back MOSFET switching topology with series and parallel capacitors to suppress impedance variations arising from device nonlinearity while maintaining a reflection phase difference of approximately 180 degrees between the ON and OFF states. A theoretical model based on transmission lines is developed and validated against full-wave co-simulations incorporating nonlinear SPICE device models. The dynamic range is evaluated with respect to both the rated current and the reflection phase difference, demonstrating stable operation up to 1.25 W. Supercell-level beam steering is further demonstrated through far-field simulations, confirming active control of the reflection angle via switching pattern reconfiguration. These results establish a foundation for the deployment of IRSs in high-power WPT scenarios.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript proposes a MOSFET-based binary control circuit for intelligent reflecting surfaces (IRS) in high-power wireless power transfer (WPT) at 2.4 GHz. It employs a back-to-back MOSFET switching topology augmented with series and parallel capacitors to suppress device nonlinearity effects and maintain an approximately 180-degree reflection phase difference between ON and OFF states. A transmission-line theoretical model is developed and validated via full-wave electromagnetic co-simulations incorporating nonlinear SPICE device models. The dynamic range is assessed with respect to rated current and phase difference, showing stable operation up to 1.25 W per unit cell, with additional far-field simulations demonstrating supercell-level beam steering through switching pattern reconfiguration.

Significance. If the numerical results hold, this work provides a practical foundation for extending IRS technology to high-power WPT scenarios, where induced currents typically damage or saturate control elements in conventional low-power designs. The back-to-back topology with capacitor compensation represents a targeted engineering solution to nonlinearity, and the combination of transmission-line modeling with nonlinear co-simulations offers a reproducible validation pathway. This could enable active beam control in wireless charging systems operating above 1 W per cell.

major comments (2)
  1. [Dynamic range evaluation / results] The dynamic range evaluation (results section) reports stable operation up to 1.25 W based on the transmission-line model and nonlinear SPICE co-simulations, but provides no quantitative error bars on the reflection phase difference or current, nor details on the number of parameter sweeps or device-to-device variations considered; this weakens the robustness claim for the 180-degree phase maintenance under nonlinearity.
  2. [Co-simulation validation] In the full-wave co-simulation setup and validation against the transmission-line model, the fidelity of the nonlinear SPICE MOSFET models (including bias-dependent capacitances and harmonic generation) at input powers above 1 W is assumed without sensitivity analysis or cross-check against measured device data at 2.4 GHz; if these models deviate from physical behavior (e.g., due to package inductance), the simulated phase stability does not necessarily translate to hardware.
minor comments (2)
  1. [Abstract and circuit description] The abstract states 'approximately 180 degrees' for the phase difference; the main text should report the exact simulated values (with and without capacitors) for both ON and OFF states to allow direct assessment of the suppression efficacy.
  2. [Supercell beam steering simulations] The far-field beam-steering demonstration would benefit from quantitative metrics such as the achieved steering angle error or sidelobe levels as a function of the switching pattern.

Simulated Author's Rebuttal

2 responses · 1 unresolved

We thank the referee for the positive assessment and recommendation for minor revision. We address each major comment below with targeted revisions to strengthen the robustness and validation claims where feasible.

read point-by-point responses
  1. Referee: The dynamic range evaluation (results section) reports stable operation up to 1.25 W based on the transmission-line model and nonlinear SPICE co-simulations, but provides no quantitative error bars on the reflection phase difference or current, nor details on the number of parameter sweeps or device-to-device variations considered; this weakens the robustness claim for the 180-degree phase maintenance under nonlinearity.

    Authors: The presented results rely on deterministic simulations with fixed manufacturer SPICE models. To strengthen the claim, the revised manuscript now includes a sensitivity study with 200 Monte Carlo trials varying MOSFET parameters (V_th ±10%, C_gs/C_gd ±20%, R_on ±15%) within datasheet tolerances. Error bars are added to the phase-difference and current plots, showing the 180° difference is maintained within ±5° up to 1.25 W with <3% current deviation, confirming robustness under realistic variations. revision: yes

  2. Referee: In the full-wave co-simulation setup and validation against the transmission-line model, the fidelity of the nonlinear SPICE MOSFET models (including bias-dependent capacitances and harmonic generation) at input powers above 1 W is assumed without sensitivity analysis or cross-check against measured device data at 2.4 GHz; if these models deviate from physical behavior (e.g., due to package inductance), the simulated phase stability does not necessarily translate to hardware.

    Authors: A sensitivity analysis varying package inductance (±30%), bias-dependent capacitances, and harmonic-generation parameters has been performed and will be added; results show phase stability is preserved. However, direct comparison to measured MOSFET data at 2.4 GHz and >1 W is not available, as this is a numerical validation study relying on vendor SPICE models. The revised text will explicitly discuss this model limitation and recommend experimental verification. revision: partial

standing simulated objections not resolved
  • Direct cross-validation of the nonlinear SPICE MOSFET models against measured device data at 2.4 GHz and input powers above 1 W, which was not performed in this numerical study.

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper develops a transmission-line theoretical model for the back-to-back MOSFET control circuit with added capacitors and validates its predictions (reflection phase difference near 180 degrees and stable operation up to 1.25 W) against independent full-wave electromagnetic co-simulations that incorporate external nonlinear SPICE device models. No load-bearing equation or claim reduces the reported power-handling limit or phase stability to a parameter fitted from the same simulation outputs, nor does any step rely on self-citation chains or imported uniqueness theorems. The derivation remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on standard assumptions of transmission-line theory and the accuracy of commercial nonlinear SPICE MOSFET models; no free parameters or new entities are introduced in the abstract.

axioms (2)
  • domain assumption Nonlinear SPICE device models accurately capture MOSFET behavior at 2.4 GHz and input powers up to 1.25 W.
    Invoked when validating the theoretical model against co-simulations.
  • domain assumption Transmission-line equivalent-circuit representation remains valid for the unit cell under the stated power levels.
    Basis of the theoretical model developed in the paper.

pith-pipeline@v0.9.0 · 5567 in / 1441 out tokens · 41102 ms · 2026-05-09T16:42:32.250088+00:00 · methodology

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Reference graph

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