Cristian Matei

Active Interferometry-Based Vector Network Analyzer Reference Impedance Renormalization

Haris Votsi, Cristian Matei, Stavros Iezekiel, Peter H. Aaen

An active interferometry-based measurement configuration for the reference impedance renormalization of a vector network analyzer is presented. The method can be implemented using only a 2-source vector network analyzer, reducing the set-up complexity required. High-impedance surface mount resistors are used to demonstrate …

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Dynamic Temperature Measurements of a GaN DC–DC Boost Converter at MHz Frequencies

Cristian Matei, Jonas Urbonas, Haris Votsi, Dustin Kendig et autres

For reliability predictions, gallium nitride transistors require accurate estimations of the peak operating temperatures within the device. This article presents a new application of thermoreflectance-based temperature measurements performed on a gallium nitride high electron mobility transistor. The submicron spatial and nanosecond temporal …

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An Interferometric Characterization Technique for Extreme Impedance Microwave Devices

Haris Votsi, Laurence T. Stant, Cristian Matei, Martin J. Salter et autres

This paper presents a microwave impedance characterization technique for extreme impedance devices. The method is based on active interferometry and uses a 2-source 4-port vector network analyzer, which allows for a compact and straight-forward implementation. A new calibration algorithm is described that …

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Measurement of the Channel Temperature of a GaN Microwave Power Transistor During Pulsed I.V Excitation

Cristian Matei, Haris Votsi, Peter H. Aaen

In this paper a thermoreflectance measurement technique is used to capture the channel temperature within a GaN-on-Si HEMT during pulsed I-V excitation. Using pulsed I-V measurements in combination with thermoreflectance measurements allows the direct assessment of the isothermal approximation that is often …

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Transient and Steady-State Thermal Measurements of GaN-on-SiC HEMT Transistors Under Realistic Microwave Drive

Jonas Urbonas, Cristian Matei, Peter H. Aaen

A new thermoreflectance and load-pull measurement set-up is presented, which enables steady-state and transient thermal imaging of RF and microwave transistors and PAs under realistic excitations. The functionality of the system is demonstrated by measuring the steady-state and transient thermal distributions of …

Poster session Wednesday 11 December all day display: 11/12/2013, 09:30-16:00 * Location: Poster area

Patrick Bertrand, Lars Grieten, C. J. P. P. Smeets, Frederik Hendrik Verbrugge et autres

Purpose: Systemic Sclerosis (SSc) involves the right heart (RH) with the appearance of pulmonary hypertension (PH). Whether SSc can directly affect RH function in absence of PH is unknown. Recently, 3D-echocardiography (3DE) and 2D-speckle tracking (2D-STE) have been validated to assess heart …