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12 pages, 460 KiB

Open AccessArticle

1/f Additive Phase Noise Analysis for One-Port Injection-Locked Oscillators

by Inwon Suh, Patrick Roblin and Youngseo Ko

Electronics 2023, 12(2), 264; https://doi.org/10.3390/electronics12020264 - 4 Jan 2023

Cited by 1 | Viewed by 1150

Abstract

The

1 / f

additive phase noise of one-port injection-locked oscillators is experimentally characterized and analyzed using a simple analytic model based on the generalized

1 / f

Kurokawa theory. To experimentally verify the prediction of the simple analytic model proposed, two negative-conductance [...] Read more.

The

1 / f

additive phase noise of one-port injection-locked oscillators is experimentally characterized and analyzed using a simple analytic model based on the generalized

1 / f

Kurokawa theory. To experimentally verify the prediction of the simple analytic model proposed, two negative-conductance transmission line pHEMT oscillators operating at 2.4828 GHz and 2.485 GHz were designed and fabricated. A new configuration for integrating an additive phase noise measurement system with a large signal network analyzer (LSNA) is introduced to jointly acquire both the noise and RF waveforms of the one-port injection-locked oscillator. The Kurokawa derivatives needed for the analytic expression were experimentally obtained using the LSNA measurements and optimized to accurately model the corner frequency. A good agreement between the predicted and experimental results was obtained for both the injection-locked and free-running oscillators. In contrast to phase noise measurements of the free-running oscillator, which can only characterize the oscillator-upconverted

1 / f^{3}

noise, the additive phase noise characterization of the injection-locked oscillator is shown to provide the means to directly observe and characterize the input-referred intrinsic

1 / f

noise source of the oscillator negative resistance. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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11 pages, 5143 KiB

Open AccessArticle

Microfabrication, Characterization, and Cold-Test Study of the Slow-Wave Structure of a Millimeter-Band Backward-Wave Oscillator with a Sheet Electron Beam

by Andrey Starodubov, Roman Torgashov, Viktor Galushka, Anton Pavlov, Vladimir Titov, Nikita Ryskin, Anand Abhishek and Niraj Kumar

Electronics 2022, 11(18), 2858; https://doi.org/10.3390/electronics11182858 - 9 Sep 2022

Cited by 2 | Viewed by 1128

Abstract

In this paper, the results of the microfabrication, characterization, and cold-test study of the previously proposed truncated sine-waveguide interaction structure with wideband-matched output couplers for the millimeter-band backward-wave oscillator (BWO) driven by a high-current-density sheet electron beam are presented. Computer-numerical-control (CNC) micromilling was [...] Read more.

In this paper, the results of the microfabrication, characterization, and cold-test study of the previously proposed truncated sine-waveguide interaction structure with wideband-matched output couplers for the millimeter-band backward-wave oscillator (BWO) driven by a high-current-density sheet electron beam are presented. Computer-numerical-control (CNC) micromilling was used to fabricate the designed interaction structure. The first sample was microfabricated from an aluminum alloy to test the milling process. The final sample was made from oxygen-free copper. Scanning electron microscopy (SEM) and optical microscopy were used to investigate the morphology of the microfabricated samples, and stylus profilometry was used to estimate the level of the surface roughness. Cold S-parameters were measured in Q- and V-bands (40–70 GHz), using a vector network analyzer (VNA). Using the experimentally measured phase data of the transmitted signal, the dispersion of the fabricated interaction structure was evaluated. The experimentally measured dispersion characteristic is in good agreement with the numerically calculated. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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11 pages, 4483 KiB

Open AccessArticle

Experimental Study of AM and PM Noise in Cascaded Amplifiers

by Inari Badillo and Joaquín Portilla

Electronics 2022, 11(3), 470; https://doi.org/10.3390/electronics11030470 - 5 Feb 2022

Cited by 3 | Viewed by 1822

Abstract

An experimental study of amplitude modulation (AM) and phase modulation (PM) noise spectra in cascaded amplifiers was carried out as a function of the number of amplification stages and the input power. Flicker and white noise contributions were determined, as well as effective [...] Read more.

An experimental study of amplitude modulation (AM) and phase modulation (PM) noise spectra in cascaded amplifiers was carried out as a function of the number of amplification stages and the input power. Flicker and white noise contributions were determined, as well as effective noise figure (NF) from AM and PM noise spectra from small-signal to large-signal regimes. Simultaneous measurements of AM and PM noise were performed, and associated correlation was measured as a function of the offset frequency from the carrier. Measurements exhibited, in general, quite low AM–PM correlation levels both in the flicker and white noise parts of the spectrum. In some particular amplifier configurations, however, measurements showed some peaks in the correlation at some specific input power levels in the transition zone, from a quasi-linear to strong compression. The results show that the effective noise figure decreases with the number of stages for a given carrier output power level. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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17 pages, 6993 KiB

Open AccessFeature PaperArticle

Identification of Buffer and Surface Traps in Fe-Doped AlGaN/GaN HEMTs Using Y₂₁ Frequency Dispersion Properties

by P. Vigneshwara Raja, Nandha Kumar Subramani, Florent Gaillard, Mohamed Bouslama, Raphaël Sommet and Jean-Christophe Nallatamby

Electronics 2021, 10(24), 3096; https://doi.org/10.3390/electronics10243096 - 13 Dec 2021

Cited by 16 | Viewed by 3267

Abstract

The buffer and surface trapping effects on low-frequency (LF) Y-parameters of Fe-doped AlGaN/GaN high-electron mobility transistors (HEMTs) are analyzed through experimental and simulation studies. The drain current transient (DCT) characterization is also carried out to complement the trapping investigation. The Y₂₂ [...] Read more.

The buffer and surface trapping effects on low-frequency (LF) Y-parameters of Fe-doped AlGaN/GaN high-electron mobility transistors (HEMTs) are analyzed through experimental and simulation studies. The drain current transient (DCT) characterization is also carried out to complement the trapping investigation. The Y₂₂ and DCT measurements reveal the presence of an electron trap at 0.45–0.5 eV in the HEMT structure. On the other hand, two electron trap states at 0.2 eV and 0.45 eV are identified from the LF Y₂₁ dispersion properties of the same device. The Y-parameter simulations are performed in Sentaurus TCAD in order to detect the spatial location of the traps. As an effective approach, physics-based TCAD models are calibrated by matching the simulated I-V with the measured DC data. The effect of surface donor energy level and trap density on the two-dimensional electron gas (2DEG) density is examined. The validated Y₂₁ simulation results indicate the existence of both acceptor-like traps at E_C –0.45 eV in the GaN buffer and surface donor states at E_C –0.2 eV in the GaN/nitride interface. Thus, it is shown that LF Y₂₁ characteristics could help in differentiating the defects present in the buffer and surface region, while the DCT and Y₂₂ are mostly sensitive to the buffer traps. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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11 pages, 8668 KiB

Open AccessArticle

Underground Imaging by Sub-Terahertz Radiation

by Yuan Zheng, Calvin Domier, Michelle Gonzalez, Neville C. Luhmann, Jr. and Diana Gamzina

Electronics 2021, 10(21), 2694; https://doi.org/10.3390/electronics10212694 - 4 Nov 2021

Viewed by 2683

Abstract

Sub-terahertz ground-penetrating radar systems offer an alternative to radio wave-based systems in the airborne imaging of buried objects. Laboratory prototype systems operating in W-band (75–110 GHz) and F-band (90–140 GHz) are presented, detecting the distance between target and source and imaging metal objects [...] Read more.

Sub-terahertz ground-penetrating radar systems offer an alternative to radio wave-based systems in the airborne imaging of buried objects. Laboratory prototype systems operating in W-band (75–110 GHz) and F-band (90–140 GHz) are presented, detecting the distance between target and source and imaging metal objects buried in mixed soil. The experimental results show that imaging in the 100–150 GHz frequency range is feasible for underground applications but significantly restricted by the attenuation characteristics of the medium covering the targets. A higher power source and more sensitive receiving components are essential to increase the penetration capability and expand the application settings of this approach. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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11 pages, 3508 KiB

Open AccessArticle

CW and Modulated Input Second Harmonic Injection for Efficiency Enhancement in Broadband Power Amplifiers

by Hsiu-Chen Chang, Patrick Roblin, Yunsik Hahn, Jose I. Martinez-Lopez and Chenyu Liang

Electronics 2021, 10(20), 2507; https://doi.org/10.3390/electronics10202507 - 14 Oct 2021

Viewed by 1647

Abstract

The second-harmonic input impedance plays a critical role on the performance of GaN power amplifiers. In a recent paper, a drain efficiency enhancement for a continuous-mode power amplifiers was reported to be achieved using active broadband second-harmonic injection at the PA input. In [...] Read more.

The second-harmonic input impedance plays a critical role on the performance of GaN power amplifiers. In a recent paper, a drain efficiency enhancement for a continuous-mode power amplifiers was reported to be achieved using active broadband second-harmonic injection at the PA input. In this paper, the strategy for selecting the second-harmonic input impedance and the necessity for using active injection in such broadband PAs are discussed in detail. Additionally, the methodology for designing an embedded broadband diplexer in the input matching network is reported. Finally, the importance of the phase of the second-harmonic signal injected is demonstrated for both CW and modulated signals using both simulation and measurement, respectively. The effectiveness of the CW and modulated active second-harmonic injection methodology presented here are validated by previously reported measurements that demonstrated an average drain efficiency improvement of 9.4% from 1.3 to 2.4 GHz for CW signals and of 9.7% at 2 GHz for a frequency-modulated 30 MHz chirp radar signal. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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13 pages, 3401 KiB

Open AccessArticle

An Ultra-Wideband Compact TR Module Based on 3-D Packaging

by Zhiqiang Li, Houjun Sun, Hongjiang Wu and Shuai Zhang

Electronics 2021, 10(12), 1435; https://doi.org/10.3390/electronics10121435 - 15 Jun 2021

Cited by 10 | Viewed by 2949

Abstract

This study presents a novel four-channel tile-type T/R module which achieves excellent performances in ultra-wideband (2–12 GHz) and integrates all circuits in a super-light (25 g) and compact (27.8 × 27.8 × 12 mm³) mechanical structure in active phased array systems. [...] Read more.

This study presents a novel four-channel tile-type T/R module which achieves excellent performances in ultra-wideband (2–12 GHz) and integrates all circuits in a super-light (25 g) and compact (27.8 × 27.8 × 12 mm³) mechanical structure in active phased array systems. The key advancement of this T/R module was to choose a Ball Grid Array (BGA) as the vertical interconnection and bracing between High-Temperature Co-fired Ceramic (HTCC) substrates in order to achieve a high-integration 3-D structure. Exploiting the HTCC multilayer layout, this paper presents the design and development of an ultra-wideband, compact and light, high-output power, four-channel, dual-polarization Transmit/Receive (T/R) Module. In this module, microwave circuits and power control circuits are highly integrated into electrically isolated HTCC layers or substrates, resulting in low coupling and crosstalk between signals. Furthermore, multichip assembly technology, multifunctional MMICs, and other high-integration technologies were adopted for this module. Each channel could provide more than 2 W transmit output power, more than 15 dB receive gain, and less than 5 dB receive noise figure. Every module contains four channels. The power supply and phase/amplitude conditioning of each channel can be controlled individually and showed good consistency of the amplitude and phase of all channels. The connectors of manifold port and polarization ports are all SSMP, which can achieve further integration. This module has also an automatic negative power protection function. The module has stabilized performance and mass production prospects. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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22 pages, 8241 KiB

Open AccessArticle

Analysis and Performance Assessment of a Real-Time Correction Pseudo-Correlation Microwave Radiometer for Medical Applications

by Enrique Villa, Beatriz Aja, Luisa de la Fuente, Eduardo Artal, Natalia Arteaga-Marrero, Sara González-Pérez and Juan Ruiz-Alzola

Electronics 2021, 10(12), 1427; https://doi.org/10.3390/electronics10121427 - 14 Jun 2021

Cited by 3 | Viewed by 2203

Abstract

A new configuration of a pseudo-correlation type radiometer is proposed for a microwave biomedical application, such as diabetic foot neuropathy. The new approach as well as its simulated performance are thoroughly assessed using commercial off-the-shelf components and custom designed subsystems. We configured a [...] Read more.

A new configuration of a pseudo-correlation type radiometer is proposed for a microwave biomedical application, such as diabetic foot neuropathy. The new approach as well as its simulated performance are thoroughly assessed using commercial off-the-shelf components and custom designed subsystems. We configured a pseudo-correlation receiver, centred at 3.5 GHz, to validate the proposal, comparing its simulated response with a measured alternative based on a 90

^{\circ}

hybrid coupler pseudo-correlation prototype. We custom designed a balanced Wilkinson power divider and a 180

^{\circ}

hybrid coupler to fulfil the receiver’s requirements. The proposed configuration demonstrated an improved noise temperature response. The main advantage is to enable the recalibration of the receiver through simultaneous measurable output signals, proportional to each input signal, as well as the correlated response between them. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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Review

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21 pages, 97302 KiB

Open AccessReview

Advances in Microwave Large-Signal Metrology: From Vector-Receiver Load-Pull to Vector Signal Network Analyzer and Time-Domain Load-Pull Implementations (Invited Paper)

by J. Apolinar Reynoso-Hernández, Manuel Alejandro Pulido-Gaytan, Thaimí Niubó-Alemán and Marlon Molina-Ceseña

Electronics 2022, 11(7), 1114; https://doi.org/10.3390/electronics11071114 - 31 Mar 2022

Cited by 2 | Viewed by 2146

Abstract

Radiofrequency (RF) power amplifiers (PAs) are important elements of modern communication systems. The most important components in PAs are the transistors, which are operated under large-signal regimes in such applications. Designing and optimizing PAs are challenging tasks that demand the highest accuracy on [...] Read more.

Radiofrequency (RF) power amplifiers (PAs) are important elements of modern communication systems. The most important components in PAs are the transistors, which are operated under large-signal regimes in such applications. Designing and optimizing PAs are challenging tasks that demand the highest accuracy on large-signal measurements at both device and circuit levels. Large-signal power transistor characterization demands the development and utilization of high-frequency and low-frequency load-pull systems. Furthermore, the static and dynamic characterization of two-input PAs requires the development of new measurement systems that consist of an nonlinear vector network analyzer (NVNA) and an arbitrary waveform generators (AWG). This paper reviews the research activities, achievements, and current research goals at CICESE Research Center in Mexico in the large-signal microwave metrology field. Full article

(This article belongs to the Special Issue Analysis and Test of Microwave Circuits and Subsystems)

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