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Impedance and low frequency noise measurements are valuable and complementary methods for electron device characterization. In this work we propose an integrated method for impedance and low frequency noise measurements in which impedance measurements are performed by means of crosscorrelation low frequency noise measurements. The method is implemented in a three-channel measurement system for the...
The thyristor level is the basic unit of HVDC converter valve, which is the core equipment in the HVDC power transmission system. Because the converter valve performance directly affect the reliability, stability and efficiency of the whole power system, each thyristor level in the converter valve needs to be test routinely during the maintenance period of the converter valve equipment. Currently...
A VSWR-protected ISM-band PA was realized using a BST based varactor for detuning of the input matching. Output VSWR levels of 30:1 can be tolerated by applying a varactor bias voltage of up to 20 V. The PA delivers 47.4 dBm output power at a maximum PAE of 49.5%. In case of high VSWR conditions the output power can be limited by detuning the varactor. It is shown that the concept protects the transistor...
This paper proposes a new cascode current source circuit that provides high-gain with improved headroom and is suitable for low-voltage amplifiers. The circuit achieves this by modifying a low-voltage cascode gate biasing circuit (“trickle-bias”) such that it amplifies the voltage of the cascode node using a PMOS input folded gain-boost amplifier. The low-voltage current source operates down to 260...
Respiratory motion is an image degradation factor in thoracic Position Emission Tomography (PET) imaging. A primary step in the majority of motion compensation approaches is gating. Unfortunately, gating usually requires an extra hardware device, which usually is unfamiliar to the medical staff making the procedure complex and error prone, and therefore, uncommon clinical practice. The primary objective...
A novel procedure for voltage standing wave ratio (VSWR) ruggedness testing of GaN-HEMTs is described. In the test the transistor is exposed to an increasing level of VSWR stress and an extensive set of marker parameters are monitored before, during, and after stress. A gate- and drain-lag pulse response test has been developed that reveals VSWR stress influence on slow surface charges. Recovery is...
A novel procedure for voltage standing wave ratio (VSWR) ruggedness testing of GaN-HEMTs is described. In the test the transistor is exposed to an increasing level of VSWR stress and an extensive set of marker parameters are monitored before, during, and after stress. A gate- and drain-lag pulse response test has been developed that reveals VSWR stress influence on slow surface charges. Recovery is...
In order to have full control of voltage controlled, power devices gate voltages must be under control. This requires low impedance (RG and LG) in gate drive circuits. A prototype of a gate drive circuits applied to an IGBT half-bridge module, results in LG of 2.5nH and gate resistance RG of 0.54 Ohm for a 400A/1200V IGBT module. Test results demonstrate the controllability of the gate voltage during...
Radio frequency power amplifiers (RF PA) are widely used for several applications e.g. wireless communication, wireless power transmission (WPT) and radio frequency heating. In general, the choice of power amplifier's operating class is based on requirements regarding linearity and power efficiency. For applications in which linearity is not a critical issue whereas high efficiency is desired, switched-mode...
The grid impedance identification is important to evaluate the effect on the power quality by renewable energy sources using inverters. It can also be used for improved design of existing grid-side filters and the control parameters for the inverters. One approach to determine the grid impedance is based on the switching of an ohmic load. The resulting transients caused by this switching can be used...
This work presents the design and implementation of a 10 W asymmetric Doherty power amplifier (ADPA) with 8.2 dB back-off at 2.2 GHz in Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs) technology. The amplifier was designed to achieve high efficiency over an increased dynamic range for applications with high peak-to-average power ratios (PAPRs). In order to obtain high efficiency upto...
This paper studies the effect of feedback capacitance on the input matching of a class E switching power amplifier. The on/off switching causes the input to see the feedback capacitance either amplified by the Miller effect or not and therefore, this feature is dependent on the gain of the amplifier. The time-varying feedback appears at the gate as negative input resistance, as a cause of severe second...
In this paper the potential and limitations of using GaN-HEMT for increased back-off efficiency in supply modulated applications is investigated. Based on extensive on-wafer class-AB load-pull characterization at varying supply voltage and input power the possible efficiency improvement is explored and the technology and device limitations are discussed. Post-processing of the measurement data shows...
Fast Id-Vg measurements on very high performance devices (very low channel ON-resistance) and larger area devices (therefore large gate capacitance) are subject to serious distortions. Methods to minimize these distortions are introduced in this paper; thus expanding the applicable range of this important measurement technique.
Continuous scaling, necessary for enhanced performance and cost reduction, has pushed existing CMOS materials much closer to their intrinsic reliability limits, forcing reliability engineers to get a better understanding of circuit failure. This requires that designers will have to be very careful with phenomena such as high current densities or voltage overshoots. In addition to the reliability issues,...
In the paper we describe a method to extract the topography of an impressed current for our bounded electrical impedance tomography (bEIT) studies. The frequency of the impressed current is low (up to a few hundred Hz), and is buried in background EEG and other noise. For the development of the extraction method, special consideration is given to maximize the signal-to-noise ratio. The standard lock-in...
We present an improved wafer-level VFTLP measurement system. This system produces pulses with sub-150 ps rise time and few distortions at the rising edge. By introducing a broadband power divider, the oscilloscope no longer limits the pulse amplitude, and arbitrarily high pulse voltages can be measured. Turn-on effects in diodes and NMOSFETs are investigated using this system.
A common gate dual MOSFET structure is proposed to improve the output impedance of SOI MOS transistors. The device consists of two transistors in series with a common gate but operates as a single device. Kink effect can be confined to the upper transistor while the overall output characteristics of the dual device are dominated by the lower transistor. As a consequence, the kink effect can be effectvely...
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