Input Bias Voltage Research Articles

Influence of optical grating on the triggering efficiency of VCSI silicon carbide photoconductive semiconductor switch

In this article, we present a new configuration of opposed-contact vanadium-compensation semi-insulating (VCSI) 4H–SiC photoconductive semiconductor switch (PCSS) to reduce the input laser energy for operation. The configuration is made up of three parts: the PCSS with optical grating, the convex lens in front of PCSS, and the additional reflector behind PCSS. Periodic surface structures were fabricated on the VCSI 4H–SiC substrate by ultrafine femtosecond laser direct writing to etch optical gratings. The microstructure on the lower surface plays the role of reflection grating, so that the laser forms a specific distribution pattern and enhances the laser absorption. Experiments and simulations show that the triggering efficiency increased 3.7 times compared to PCSS without grating at 532 nm laser. And output voltage can reach 90 % of the input bias voltage. This SiC PCSS optical system significantly reduces the laser energy without reducing the electrodes spacing.

A PIN photodiode ionizing radiation detector with small angular dependence and low buildup

PurposeTo develop an improved PIN photodiode detector that has low angular dependence and small buildup. Show that the measured dose compares well with the dose calculated by a treatment planning system for static fields at oblique angles and rotationally delivered fields. MethodsCommercially available PIN photodiodes, VEMD1060X01, (Vishay Semiconductor, Shelton, CT), are fabricated into detectors that can be used for measurement of ionizing radiation. PIN photodiodes are soldered onto coaxial cables in an edge-on orientation and are mounted in a symmetrical package. Detector signals are measured with an electrometer with zero input bias voltage. Dose is measured from a Varian Trilogy (Varian Medical Systems, Milpitas, CA) linear accelerators 6 MV photon and 6 MeV electron beams. An Eclipse (Varian Medical Systems, Milpitas, CA) commercial treatment planning system Acuros and electron Monte Carlo algorithms are used for calculating dose expected in various irradiation geometries. ResultsThe single diode detector has an angular dependence between −1.1% and +1.2% and a buildup of 0.6 mm water equivalence. Measurements of dose at 0.3, 0.5, 1.0 and 1.5 cm depth from oblique static beams and from intensity modulated radiation therapy (IMRT) delivered beams agree with planning system calculations within ±1.5%. ConclusionsA clinically useable dose detector can be fabricated from a PIN type photodiode. This diode detector can be used to measure dose at the surface of a patient under a bolus if one is used. Measurements agree with calculations for static fields at oblique angles as well as rotational IMRT delivered beams.

Analysis and Design of High-Efficiency Charge Pumps With Improved Current Driving Capability Using Gate Voltage Boosting Technique

This paper presents two high-efficiency charge pumps (CPs) by utilizing the gate voltage boosting technique (GVBT). Unlike traditional bulk-CMOS and all-NMOS CPs, an input bias voltage is independently applied to the gate terminal, and it improves the current driving capability without the need of large pumping capacitors or high-frequency clocks. Meanwhile, the GVBT decouples the state of transistors from the clocks connected to the pumping capacitor, and it can eliminate the reversion loss in both main and auxiliary circuits. Fabricated in a 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> standard CMOS technology, the single-stage all-NMOS CP achieved a maximum output voltage of 6.589 V and a peak power efficiency of 80.08%. We also implemented the bulk-CMOS CP with GBVT for comparison, the single-stage all-NMOS CP achieved <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 1.24\times $ </tex-math></inline-formula> more output voltage than the bulk-CMOS CP under a load current of 1.5 mA. The voltage errors of the all-NMOS CP between the analytical and the measured results are less than 7%.

The simulation of influence of main components’ parameters of reference voltage sources on output voltage

The aim of the research is to develop a model of the reference voltage source that can be modeled the influence of the main structural components’ parameters of reference voltage source on the accuracy and temperature stability of the output voltage. The article analyzes the current state of reference voltage sources in integrated circuits. It was established that reference voltage sources are one of the main blocks of each integrated chip. It was found that requirements are for these sources are the next: they must have low sensitivity to changes in supply voltage, temperature, and deviations of the parameters of the technology process. In this case, the reference voltage sources must operate at a supply voltage equal to or less than 1V to meet modern aspects of the application. A possible approach to the construction of a reference voltage source having a temperature-independent output voltage and capable of operating at a supply voltage equal to or less than 1V is proposed in this article. This solution has the ability to implement in the standard CMOS technology for integrated circuits. An analysis of possible sources of error that degrade the accuracy of the output voltage of the reference voltage source is provided. It was established that the bias voltage of the operational amplifiers has the strongest effect on the accuracy of the output voltage. An idealized model is proposed, which contains ideal resistors and operational amplifiers – the components that most strongly affect the accuracy and stability of the output voltage of the voltage references. An operational amplifier model has been developed that is able to model the input bias current, input bias voltage, input resistance, differential gain, output resistance and frequency response of the operational amplifier. The influence of voltage gain, bandwidth, output resistance of the operational amplifier, input bias voltage on the nominal output voltage and the temperature coefficient are investigated. A regression analysis was performed to display in a polynomial of the 4th order form like , temperature dependence of the currents generated in the circuit. This allows you to choose the correct values of current transfer coefficients in the current mirrors to reduce the temperature dependence of the output voltage.

Optimizing energy harvesting performance of cone dielectric elastomer generator based on VHB elastomer

Dielectric Elastomer Generator (DEG) has been used to harvest energy from reciprocating mechanical motion due to its variable capacitance under tension, and thus it has attracted widespread attention in the last decade. In this study, a cone DEG based on VHB elastomer was developed and its energy harvesting performance was optimized by combining equibiaxial prestretching to cone stretching mode and then tailoring the variables such as the equibiaxial prestretch ratio, input bias voltage and cone displacement. The coupling relationship among these variables and their combined influences on generated energy, energy density and conversion efficiency were systematically studied for the first time. The results indicate that prestretching plays an important role in achieving the target energy harvesting performance at shorter displacement and lower bias voltage, which means lighter weight and portability of the device. More importantly, an up-to-date highest energy density of 130 mJ/g or a maximum electromechanical conversion efficiency of 40% could be obtained by optimizing the variables. In addition, the concept of “displacement threshold” in DEG was firstly proposed and discussed based on leakage and viscoelastic. This work provides ideas for future applications of DEG on portable power and array power generators with high energy harvesting performance.

Design and Testing of the Space Floating Potential Detector

A space floating potential detector (FPD) is an instrument being developed to study the charging of spacecraft structures. It measures the floating potential that arises as the spacecraft interacts with the low Earth orbit (LEO) plasma as well as the Earth’s magnetic field. The FPD belongs to the active potential control system and consists of three functional modules. Leakage current-eliminating and zero-clearing techniques are used in the detector design to ensure the measurement of the floating potential over the long term within the range from −150 to 0 V and at a voltage resolution of less than 1 V. In order to investigate the performance of the FPD, a typical LEO space plasma environment is simulated in the laboratory. The calibrations of the FPD show that the output voltage is basically linear with the input bias voltage, and the maximum nonlinear error is less than 0.9%.

PIN diodes for radiation therapy use: Their construction, characterization, and implementation

PurposeDevelopment and implementation of a PIN diode measurement system that can measure dose on the surface of a patient, which can be compared to dose calculated by a treatment planning system. Measurements are to be possible for static or rotational photon beams and electrons. Simple calibration procedures are to be devised that require a minimum set of correction factors. MethodsReadily available PIN type photodiodes are fabricated into devices that can be used for detection of ionizing radiation. Single or dual PIN diodes are soldered onto flexible shielded cables for static and rotational irradiation use. Diode signals are measured with an electrometer with zero input bias voltage. Diode temperature is determined by operating it as a thermistor. Linac photon and electron dose is measured. A commercial treatment planning system is used for calculating dose expected in various test geometries. ResultsThe scanning and surface diodes have an intrinsic buildup of 0.3 mm water equivalence and the IMRT device a buildup of 1.5 mm. Correction factors are determined for changes in diode sensitivity with the following factors: dose-per-pulse, dose rate, angle of radiation incidence, temperature, and field size. The surface or IMRT diode detector measurements agree within 1.0% with Eclipse calculations. ConclusionsClinically useable dose detection devices can be fabricated from PIN type photodiodes. These diodes are used to measure dose at the surface of a patient or under bolus. Correction factors are unnecessary if a surface or IMRT type device is chosen for use with static orthogonal or rotational IMRT delivered beams, respectively.

Oxide Thin-Film Electronics on Carbon Fiber Reinforced Polymer Composite

In this letter, the direct fabrication of amorphous indium-gallium-zinc-oxide thin-film transistors (TFTs) and circuits on a commercial carbon fiber reinforced polymer (CFRP) substrate is demonstrated. The CFRP is encapsulated with a $\approx 10.6-\mu \text{m}$ -thick resin layer, although the surface roughness and temperature sensitivity of the substrate are not ideal for the fabrication of electronic devices, we present depletion mode TFTs exhibiting a field effect mobility of $18.3~\text {cm}^{2}\text {V}^{-1}s^{-1}$ , and a common source amplifier, providing a voltage gain of 8 dB and a −3 dB cutoff frequency of 11.5 kHz. The amplifier does not require any input bias voltage and can, hence, be directly used to condition signals originating from various transducers, e.g., piezoelectric strain sensors used to monitor the structural integrity of CFRP elements. This opens the way to the fabrication of smart mechanical CFRP parts with integrated structural integrity monitoring systems.

Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

Real-time DC-dynamic biasing method for switching time improvement in severely underdamped fringing-field electrostatic MEMS actuators.

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

A Regulated Charge Pump With Small Ripple Voltage and Fast Start-Up

A regulated charge pump circuit is realized in a 3.3-V 0.13-/spl mu/m CMOS technology. The charge pump exploits an automatic pumping control scheme to provide small ripple output voltage and fast start-up by decoupling output ripple and start-up time. The automatic pumping control scheme is composed of two schemes, an automatic pumping current control scheme and an automatic pumping frequency control scheme. The former automatically adjusts the size of pumping driver to reduce ripple voltage according to output voltage. The latter changes the pumping period by controlling a voltage-controlled oscillator (VCO). The output frequency of the VCO varies from 400 kHz to 600 kHz by controlling the input bias voltage of the VCO. The prototype chip delivers regulated 4.5-V output voltage from a supply voltage of 3.3 V with a flying capacitor of 330 nF, while providing 30 mA of load current. The area is 0.25 mm/sup 2/ and the measured output ripple voltage is less than 33.8 mV with a 2-/spl mu/F load capacitor. The power efficiency is greater than 70% at the range of load current from 1 to 30 mA. An analytical model for ripple voltage and recovery time is proposed demonstrating a reasonable agreement with SPICE simulation results.

Low-voltage CMOS current amplifier and its use for high-performance voltage amplification

A CMOS current operational amplifier (COA) is exploited to obtain a voltage amplifier operating at 1 V and with an input bias voltage of 0.5 V. The COA employs a class AB input stage that enhances the slew-rate performance and provides accurate control of both the quiescent currents and the input bias voltage. It exhibits a 56 dB loop gain with a gain-bandwidth product of 18 MHz. Based on this COA, a 1-V voltage amplifier is implemented. It provides a constant closed-loop bandwidth of about 2 MHz and exhibits a THD better than -60 dB for a 1 MHz 600 mV/sub pp/ output signal.

Observation of macroscopic quantum effects in high T/sub c/ weak link superconducting rings

Thin-film weak link rings were constructed using high-T/sub c/ YBaCuO superconducting thin films. The thickness of the films was 5000 AA. The weak links were biased with an AC induced current. The resulting electron pair charges on the weak links were monitored by an output voltage. The charge stored on the link (as a function of the input bias voltage) is consistent with that of a macroscopic quantum pendulum.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Observation of Macroscopic Quantum Effects in YBCO Thin Film Microbridge Rings

ABSTRACTThin film rings with microbridge were constructed using high Tc Y-Ba-Cu-O super-conducting thin films which were made by laser ablation on the single crystal MgO(100) substrates. The thickness of the films is 5000 Å. The weak links were biased with an AC induced current. The resulting electron pair charges on the weak links were monitored by an output voltage. The charge stored on the link (as a function of the input bias voltage) is consistent with that of a “macroscopic quantum pendulum”

MOS analog function synthesis

The design of a monolithic MOS parametric analog function synthesizer is described. The contour and voltage scaling of the nonlinear function to be synthesized are determined by a set of input bias voltage parameters, and are independent of temperature and processing variations. Experimental results showing synthesis precision on the order of 2% over temperature are presented. The particular application of generating a voltage that is a nonlinear function of chip temperature for compensation purposes is addressed.