Higher Order Harmonic Distortions Research Articles

Study of ambipolar and linearity behavior of the misaligned double gate-drain dopant-free Nano-TFET: Design and performance enhancement

Work done in this article demonstrates the charge plasma based misaligned double gate-drain doping less tunnel field effect transistor. Designed devices such as perfectly aligned and misaligned, both are optimized by considering the secondary drain in order to investigate ambipolar and linearity behavior. As the work function of secondary drain increases reduction in the ambipolar current is observed with a little degradation in ON state current. It presents a tradeoff between ambipolar current and ON current hence suitable work function of secondary drain is necessary for the proper working of the device. Analog parameters such as ON current, ambipolar current, subthreshold slope, ON to OFF current ratio, ON current to ambipolar current ratio, threshold voltage are analyzed with respect to secondary drain. In order to investigate the device performance for low voltage and low noise applications various linearity parameters such as higher order transconductances, higher order harmonic distortions, higher order intermodulation point and transconductance gain factor have also been demonstrated all the designed structures. The values of ON current for perfectly aligned, underlap, overlap and both gate misaligned structure at 4.2eV of secondary drain work function is 52 μA, 30 μA, 18 μA and 12 μA respectively. And ambipolar current for perfectly aligned, underlap, overlap and both gate misaligned structure at 4.2eV of secondary drain work function is 3 pA, 23 pA, 247 pA and 705 pA respectively.

Dynamic Phase Extraction in an Ameliorated Distributed Vibration Sensor Using a Highly Stable Homodyne Detection

In this work, a highly stable homodyne phase demodulation scheme is proposed and experimentally demonstrated in an ameliorated distributed vibration sensor (DVS) using dual-wavelength probes and direct-detection receivers. According to the difference between central wavelengths of two probes, the vibration location and the frequency information can be simultaneously demodulated using a reflectometer and an interferometer in direct-detection receivers. An improved phase demodulation scheme is then employed in the interferometer part for the vibration sensing, since it is robust against the high-order harmonic distortion (due to nonlinearity) and the light intensity disturbance, and it is also fully independent of the applied modulation depth. Different patterns of piezoelectric transducer induced vibration are applied to the fiber under test. Experimental results demonstrate that the low harmonic distortion and the accurate phase extraction in the improved phase demodulation scheme make a good agreement with the theoretical analysis. This indicates that the proposed scheme will greatly extend the detected scope of the DVS, in which the quantitative measurement of vibrations is necessary.

Low and high order harmonic distortion in the presence of fast charging stations

The aim of this paper is to assess the harmonic emission from fast charging stations at both the low-order and high-order harmonics. New three-phase effective power quantities are developed at both the low-order (harmonics below 40th order) and high order (harmonics above 40th order) and are used to quantify such harmonic impact. Chargers from two different manufacturers are used in this study and the real measurement are performed at fast charging stations in Canada. The results have shown that chargers from different manufacturers may contribute differently in terms of the harmonic current distortion levels reaching 18% at the system level. Furthermore, the time-frequency spectrum of the current obtained from chargers of different manufacturers are different at both the low-order and high-order harmonic current distortion. The results have also shown that the new three-phase power quantities defined in this work are useful in identifying the chargers with high contribution to both the low-order and the high-order harmonics distortion/interference by separating the power quantities defined in the IEEE Standard 1459-2010 into several power quantities at the low-order harmonic (ranging from 2nd to 39th harmonic order or below 2.4 kHz) and the high-order harmonics (beyond 40th harmonic order or beyond 2.4 kHz).

Performance Assessment of the Charge-Plasma-Based Cylindrical GAA Vertical Nanowire TFET With Impact of Interface Trap Charges

In this article, a charge-plasma (CP)-based gate-all-around (GAA) silicon vertical nanowire tunnel field-effect transistor (NWTFET) is proposed. The effects of interface trap charges (ITCs) on dopingless (DL) NW-based device have been addressed for the first time. CP technique is used to induce charge carriers within the drain/source regions by depositing layers of metals with specific work function. Linearity performance parameters such as higher order harmonic distortions (HDs), intermodulation distortions (IMDs), and interception points are calculated including the effects of ITCs on the cylindrical channel-surround gate-oxide interface. This work shows that positive ITCs can help in improving the device characteristics, whereas negative ITCs degrade the device performance. The ON-state current to OFF-state current ratio decreases for either polarity of ITCs. The ON-state current has been improved by approximately 50% with higher positive ITCs. The presence of positive ITCs in DL NWTFET improves the driving capability to be used for analog applications. The linearity parameters tend to improve with positive ITCs and degrade with negative ITCs. The proposed device has reached the same cutoff frequency at lower operating gate bias (approximately 0.8 V) with half the threshold voltage for higher positive ITCs.

Pure sinusoidal photo-modulation using an acousto-optic modulator.

We use an arbitrary waveform generator to generate a clean sinusoidal modulation from the otherwise nonlinear acousto-optic modulator (AOM). A closed loop optimization script is applied to reduce high order harmonic distortion to less than 0.05% in a high AOM diffraction efficiency regime. This low level of distortion allows us to measure the nonlinear response to photoexcitation of many materials. We demonstrate this technique in a pump-probe experiment to measure the Nonlinear Photo-Modulated Reflectivity (NPMR) of surfaces. NPMR served us as the basis for developing super-resolution microscopy for non-fluorescence samples (label-free) as well as a tool in studying the ultrafast nonlinear response of photo-excited plasmonic nano-structures. Our methodology could be applied to other imaging systems in which measuring nonlinearity is desirable, such as fluorescence and photoacoustic microscopy.

Therapeutic Effect Enhancement by Dual-bias High-voltage Circuit of Transmit Amplifier for Immersion Ultrasound Transducer Applications.

The dual-bias high-voltage circuit of a transmit amplifier for immersion ultrasound transducer applications is proposed to enhance the therapeutic effect of human HeLa cells. High-voltage output signals generated from a transmit amplifier are typically preferable for immersion ultrasound transducers owing to their high sensitivity at the desired frequency. However, high-voltage output signals typically produce high-order harmonic distortions, thus triggering several unwanted high-order spectral signals in the ultrasound transducers. By reducing high-order harmonic distortions, we expect that improving the signal quality of excited pulses for immersion ultrasound transducers would be beneficial for the therapeutic effect on human cervical cancer HeLa cell suppression. Therefore, an additional bias circuit is developed to merge with the original bias circuit for transmit amplifier to control the harmonic distortions of the immersion ultrasonic transducer. To properly select the components of dual-bias high-voltage circuit, we need to calculate and measure the DC bias voltages of the transmit amplifier with and without dual-bias high-voltage circuit for different period of the time for therapeutic applications. To evaluate the performances of the developed circuit, pulse-echo measurements using a transmit amplifier with or without dual-bias high-voltage circuit were obtained. The measured second, third, and fourth harmonic distortions of the echo signals when using the transmit amplifier with dual-bias high-voltage circuit at 10 V DC bias voltage are lower than those when using the transmit amplifier only. Subsequently, the therapeutic effects using the enhanced performances of the transmit amplifier with dual-bias high-voltage circuit were verified and compared with those using the performances of the transmit amplifier by comparison of quantitative changes in HeLa cell concentrations. The control group without any ultrasonic induction increased the cell density up to about 100% on Day4, however the experimental groups with ultrasonic induction (TA = 91.2 0.8%, TA+Dual-bias high-voltage circuit (0.8 V) = 78.8 1.7% and TA+Dual-bias high-voltage circuit (10 V) = 66.3 1.1%) showed statistically significant cell density changes compared to the control group. We confirmed that the therapeutic effect from using the dual-bias high-voltage circuit is improved. Therefore, it can be a potential candidate to improve the therapeutic effect of HeLa cells.

A Hybrid CBPWM Scheme for Single-Phase Three-Level Converters

A novel hybrid carrier-based pulse width modulation (CBPWM) scheme that combines unipolar and dipolar modulations is proposed for single-phase three-level rectifiers, which are widely applied in railway traction drive systems. The proposed CBPWM method can satisfy the volt-second balancing principle in the complete modulation index region through overmodulation compensation. The modulation scheme features two modulation modes: unipolar and dipolar. The operation range limits of these modulation modes can be modified by changing the separation coefficient. In comparison with the traditional unipolar CBPWM, the proposed hybrid CBPWM scheme can provide advantageous features, such as lower high-order harmonic distortion of the line current and better utilization of switching frequency. The separation coefficient value is optimized to achieve the maximum utilization of these advantages. The experimental results verify the feasibility and effectiveness of the proposed hybrid CBPWM scheme.

A low distortion CMOS analogue switch with high-order compensation

A novel bootstrapped analogue switch with high-order harmonic distortion compensation applied in the multiply digital-to-analog convertor (MDAC) of high-speed and high-resolution pipelined analog-t...

New power quantities definition for low and high order harmonic distortion

This paper presents a set of new power quantities that aims to assess the harmonic distortion considering low and high order harmonics. The power quantities in the IEEE Standard 1459-2010 are revisited and new formulations are developed after separating the low order (harmonics below 40th order) and high order (harmonics above 40th order) from the fundamental (i.e. 60-Hz) component of the voltage and current. Two distinct groups of new power quantities are introduced in this study namely: (1) low/high order harmonic distortion powers and (2) low/high order harmonic interference powers. The results of the experimental measurement performed on different light bulb types from different manufacturers are presented in this paper to exemplify the usefulness of the developed power quantities. The results of the measurement reveal that the new power quantities can be useful in assessing the harmonic distortion/interference resulting from low/high order harmonics and also can be useful in many detection applications which require extracting prominent features in high frequency range above 2.4kHz (or 40th harmonic order).

Practical Solutions for Broadband and Time-Varying Interharmonic Problems

Interharmonic frequencies produced by nonlinear loads, such as induction heaters, are broadband and time varying. When one of these interharmonic frequencies coincides with the system resonant frequencies, harmonic resonance can occur. Multistage series and shunt filters are often ineffective for controlling such a problem. This paper presents two practical yet effective solutions to mitigate time-varying and broadband high-order harmonic distortions. A utility-side solution involves shifting the system frequency response to a harmless frequency so that interharmonic currents cannot excite the system into resonance. A customer-side solution involves blocking interharmonic currents from entering the utility system using a low-pass broadband filter approach. Both solutions can be accomplished using appropriately sized capacitor banks

Fabrication of digital sinusoidal gratings and precisely controlled diffusive flats and their application to highly accurate projected fringe profilometry

Fabrication of digital sinusoidal gratings and precisely controlled diffusive flats and their application to calibration-based highly accurate phase-shifting projected fringe profilometry are presented. The main advantages of using digital sinusoidal gratings are (1) high geometrical accuracy (< 1 μm); (2) high contrast ratio; and (3) very low high-order harmonic distortion. In addition, a high-quality diffusive flat with precisely controlled lateral correlation length, fabricated by VLSI processes, offers a good calibration standard. It is found that, by applying these two components to the calibration-based phase-shifting projected fringe profilometry, absolute 3-D surface profile measurement accuracy on the order of microns can be achieved.