Current Transfer Ratio Research Articles

An online comprehensive health monitoring system for automotive auxiliary converter

Abstract As an essential part of the electronic system in electric vehicles (EVs), the automotive auxiliary converter (AAC) connects the batteries and burdens the auxiliary power supply. This paper mainly proposes an online comprehensive health monitoring system for AAC. Firstly, based on the control diagram of the LLC resonant converter, three critical components are emerging, including capacitor, optocoupler, and semiconductor. These components can partly reflect the operation condition of the output loop, feedback loop, and control link, respectively. Then the characteristics parameters of these three components, equivalent series resistance (ESR) of the capacitor, current transfer ratio (CTR) of the optocoupler, and on-resistance of the semiconductor jointly construct the three-dimensional health monitoring vector. Finally, the online monitoring accuracy is verified and the proposed system can thus effectively promote the operation and maintenance of AAC. Furthermore, the online health monitoring system enables a flexible expansion, which can be further customized into different kinds of power converters, showing high applicability and practicality.

Development of LTCC-packaged optocouplers as optical galvanic isolation for high-temperature applications

This paper reports high-temperature optocouplers for signal galvanic isolation. Low temperature co-fired ceramic (LTCC) technology was used in the design and fabrication of the high-temperature optocoupler package. The optimal coupling behaviors, driving capabilities and response speed of the optocouplers were concentrated and investigated in this paper. Emitters and detectors with different emission and spectral wavelengths were studied to achieve optimal coupling behaviors. Relatively high coupling efficiency is achieved with emitters and detectors of emission and spectral wavelength in the red spectrum (i.e., 620–750 nm), leading to higher current transfer ratios (CTR). To further enhance the electrical performance, optocouplers with multiple detectors in parallel were designed and fabricated. CTR, leakage current and response speed (i.e., propagation delay, rise time and fall time) of the optocouplers were characterized over a range of temperatures from 25 to 250 °C. The CTR degrades at high temperatures, while the leakage current and response speed show little degradation with varying temperatures. Furthermore, the behaviors of the optocouplers with varying temperatures are modeled and analyzed.

An Online Proactive CTR Monitoring Method for Optocoupler in Automotive Auxiliary Converter

Automotive auxiliary converter empowers the electronic system, the failure of which will affect the system performance. As a critical component in the feedback loop of the converter, real-time health monitoring for optocoupler is of great importance. The degraded optocoupler mainly shows a falling current transfer ratio (CTR). This article proposes an online proactive CTR monitoring method for optocoupler via voltage measurement of critical nodes. The monitored CTR can indicate the health condition of the optocoupler. First, the principle of a boost- LLC converter is analyzed in detail. Then, the influences of degraded CTR on the feedback loop are derived. An online proactive CTR monitoring scheme is introduced. The realization of voltage measurement, signal filtering, wireless communication, and time synchronization are in two independent embedded systems. CTR will be calculated in the local server and be stored in the local database. The proposed method can monitor CTR for both unaged and aged optocouplers. Effects of switching frequency and ambient temperature are also incorporated for online CTR monitoring. Experimental results validate the superiority of this online proactive monitoring method. The method could be extended and further evaluate the health condition of the overall automotive auxiliary converter.

Electron Beam Induced Degradation in Electrical Characteristics of Optocoupler

This article describes the electrical degradation in the I-V characteristics and the Current Transfer Ratio (CTR) of commercial optocoupler (4N35) exposed to an electron beam. The devices are exposed to an electron beam of various doses and the I-V characteristics of LED and output characteristics of the phototransistor are measured as a function of accumulated electron dose. The result indicates that 10 MeV electron of 1.5 kGy dose results in considerable degradation in CTR. Further, it appears that the phototransistor of the optocoupler is more susceptible to radiation damage than the LED part and care must be exercised when these devices are used for space applications.

Displacement damage in optocouplers induced by high energy neutrons at back-n in China Spallation Neutron Source**Project supported by the National Natural Science Foundation of China (Grant Nos. 11875223, 11805155, and 11690043), the Chinese Academy of Sciences Strategic Pilot Science and Technology Project (Grant No. XDA15015000), the Innovation Foundation of Radiation Application, China (Grant No. KFZC2018040201), and the Foundation of State

Neutron radiation experiments of optocouplers at back-streaming white neutrons (back-n) in China Spallation Neutron Source (CSNS) are presented. The displacement damages induced by neutron radiation are analyzed. The performance degradations of two types of optocouplers are compared. The degradations of current transfer ratio (CTR) are analyzed, and the mechanisms induced by radiation are also demonstrated. With the increase of the accumulated fluence, the CTR is degrading linearly with neutron fluence. The radiation hardening of optocouplers can be improved when the forward current is increased. Other parameters related to CTR degradation of optocouplers are also analyzed.

Modeling the performance characteristics of optocoupler under irradiated fields

Optoelectronic devices, including optocouplers, are used in optical communication, controlling and sensing applications. Many of these applications are used under the influence of radiation; in some applications, it is difficult to shield the devices from radiation. The interaction of radiation with devices materials produces the defects. Several studies have been conducted on the effects of radiation on the optocoupler; most of them were interested in practical experiments, recording and describing the results. The behavior of an irradiated optocoupler still needs a mathematical model that can describe the optical and electrical characteristics of the device under the effect of radiation. This paper presents a mathematical model that includes the governing equations of the radiation effect in digital optocouplers. The validity of the model is verified by comparing its numerical values with the previous experimental results of neutrons and gamma radiations’ effects in one of the most popular digital optocouplers (4N49); the maximum error of the current transfer ratio of the device is 14% at 100 krad gamma dose and error reduces at the low doses. By adapting input parameters, this model can be applied to describe the effect of other types and doses of radiation on different types of optocouplers.

Degradation of non-linear optocouplers induced by 60 MeV proton irradiation

Abstract In this paper, the experiments of proton irradiation on optocoupler are presented. The degradations of current transfer ratio (CTR) are analyzed, and the mechanisms induced by radiation are also demonstrated. The degradations of primary photocurrent are analyzed, which may be attributed to the photoresponse degradation in collector-base junction of phototransistor. The parameter degradations of light-emitting diode (LED) after irradiation play a role too. The degradations of transistor gain change the dependence of CTR on forward current. Finally, integration research from the irradiation-sensitive parameter degradation to the CTR degradation of the optocoupler is achieved.

Low-power-consumption optical interconnect on silicon by transfer-printing for used in opto-isolators

On-chip optical interconnects heterogeneously integrated on silicon wafers by transfer-print technology are presented for the first time. Thin (<5 µm), micron sized light-emitting diodes (LEDs) and photo diodes (PDs) are prefabricated and transfer-printed to silicon wafer with polymer waveguides built between them. Data transmission with total power consumption as low as 1 mW, signal to noise ratio of >250 and current transfer ratio of 0.1% in a compact volume of <0.0004 mm3 are demonstrated. Experiment shows that the polymer waveguide between the LED and PD plays a key role in enhancing the data transmission efficiency. Reciprocal performance for bidirectional transmission is also achieved. The results show the potential for cost-effective and low profile form-factor on-chip opto-isolators.

High-Performance Photocoupler Based on Perovskite Light Emitting Diode and Photodetector.

Photocoupler is a kind of semiconductor optoelectronic device that integrates light-emitting device (LED) and photodetector. It has found wide application in various fields because of its capability to transmit the electrical signal through the conversion of the electricity-light-electricity. Herein, we report the fabrication of a new photocoupler by simply integrating perovskite quantum dots LED and perovskite photodetector on a glass substrate. The as-fabricated photocoupler showed outstanding characteristics with high current transfer ratio (CTR) of 3.35%, which is highly competitive in comparison with other materials based devices. Furthermore, the perovskite photocoupler had a fast response speed of 8 μs/8.26 μs. By further adding an amplification circuit, the CTR could be enhanced by around 50 times to 172.6%. These results indicate that the present perovskite-based photocouplers may find potential application in future integrated circuit and optoelectronic system.

Online Degradation Detection/Prediction Method for Current Transfer Ratio of Photo-Coupler Installed in Digitally-Controlled Switching Mode Power Supply

Online Degradation Detection/Prediction Method for Current Transfer Ratio of Photo-Coupler Installed in Digitally-Controlled Switching Mode Power Supply

A Method to Separate Proton Damage in LED and Phototransistor of Optocouplers

This paper reports proton damage in light-emitting diode (LED) and phototransistor of the Micropac 66296 optocoupler. Our results show that the optocoupler current transfer ratio (CTR) data are influenced by the gain of the phototransistor. Analysis of the test data reveals interesting information, such as the dependence of the phototransistor gain on irradiation and photocurrent. Only a small reduction of phototransistor gain is observed with increasing irradiation when the irradiation is sufficiently large. The phototransistor gain reduction is more significant when comparisons are made with the unirradiated case. Statistical analysis is performed, using a one-sided tolerance method, on the LED light intensity and the optocoupler CTR data. Mean and statistically derated values of the optocoupler CTR and the LED light intensity data at room temperature are presented.

Lifetime prediction of optocouplers in digital input and output modules based on bayesian tracking approaches

Digital input and output modules are widely used to connect digital sensors and actuators to automation systems. Digital I/O modules provide flexible connectivity extension to numerous sensors and actuators and protect systems from high voltages and currents by isolation. Components in digital I/O modules are inevitably affected by operating and environmental conditions, such as high voltage, high current, high temperature, and temperature cycling. Because digital I/O modules transfer signals or isolate the systems from unexpected voltage and current transients, their failures may result in signal transmission failures and damages to sensitive circuitry leading to system malfunction and system shutdown. In this study, the lifetime of optocouplers, one of the critical components in digital I/O modules, was predicted using Bayesian tracking approaches. Accelerated degradation tests were conducted for collecting the critical performance parameter of optocouplers, current transfer ratio (CTR), during their lifetime. Bayesian tracking approaches, including extended Kalman filter and particle filter, were applied to predict the failure. The performance of each prognostic algorithm was then compared using accuracy and robustness-based performance metrics.

A Class of Quasi-Cuk DC/DC Converters: Steady-State Analysis and Design

In this paper, new topologies for quasi-Cuk converter are proposed. The proposed converters with different voltage and current transfer ratio and reduced voltage stress on capacitor can be employed in distributed generation (DG) systems. In this paper, steady-state analysis of two proposed quasi-Cuk converters in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is presented. Then, besides values designing of used elements, maximum and minimum values of their current and voltage are calculated. Moreover, critical inductances between CCM and DCM for the proposed converters are calculated. Unique features of the proposed converters are different transfer ratio without employing additional elements compared to the conventional Cuk converter. Comparison of the proposed converters with conventional converter in terms of voltage transfer ratio, voltage stress on capacitor, and voltage stress on switch demonstrates advantages of the proposed converters. Finally, experimental results to verify the accuracy of the proposed converters in different operating modes are presented.

Bidirectional Quasi-Cuk DC/DC Converter with Reduced Voltage Stress on Capacitor and Capability of Changing the Output Polarity

In this paper, a bidirectional topology for quasi-Cuk dc/dc converter with capability of zero-voltage and zero-current-switching (ZVZCS) is proposed. The bidirectional quasi-Cuk (BQ-Cuk) converter has different voltage and current transfer ratio, reduced voltage stress on capacitor and capability of changing the output polarity in comparison with conventional bidirectional Cuk converter. In this paper, steady-state analysis of the quasi-Cuk converter with capability of ZVZCS in turn-on is presented. Then, critical inductances for transient from this operation to two new operations are calculated. Next, besides values designing of used elements, maximum and minimum value of their current and voltage are calculated. Finally, experimental results to verify the accuracy of the proposed converter in different operating modes are presented.

Analysis of current mirror circuits designed with line tunnel FET devices at different temperatures

The goal of this work is to study the performance of current mirror circuits designed with line tunnel field effect transistor (TFET) devices and compare the suitability of this technology with alternatives such as point TFETs and FinFETs. Experimental results have been obtained at room and high temperatures and the analyses focused on parameters such as the magnitude of the on-state current and the sensitivity of the current transfer ratio to channel dimensions mismatch and to the temperature. Line TFETs exhibited higher on-state current than point TFETs, in spite of a higher susceptibility to the channel length. When band-to-band tunneling prevails for both input and output transistors, the current transfer ratio with line TFETs presented a nearly linear dependence on the temperature due to bandgap narrowing. This way, a general equation of the current transfer ratio for circuits designed with the three highlighted technologies is proposed. Globally, it was observed that, unless a very low sensitivity to channel length mismatch is required, line TFET devices are a very suitable alternative for current mirror circuits, since this technology provides much higher on-state currents than point TFETs, and at the same time it is much less sensitive to temperature variations than FinFET transistors.

Collision Cascade and Spike Effects of X-ray Irradiation on Optoelectronic Devices

Bombardment with high energy particles and photons can cause potential hazards to the electronic systems. These effects range from degradation of performance to functional failure, which can affect the operation of a system. Such failures become increasingly likely as electronic components are getting more sophisticated, while decreasing in size and tending to a larger integration. In this paper, the effects of X-ray irradiation on a plastic encapsulated infrared light emitting diode, coupled to a plastic encapsulated silicon infrared phototransistor, with both of them being electrically isolated at ON and OFF modes, are investigated. All the devices are exposed to a total dose of up to 1000 mAs. The electrical parameters of the optoelectronic devices during the radiation exposure and at post-irradiation are compared to the pre-irradiation readings. The findings show that the highest degradation occurs at low dose of exposure; beyond 100 mAs the relative decrease in collector current of the phototransistor is gradually reduced. The most remarkable feature found, is the operational dependence of the bias collector current, indicating a higher degradation for low bias forward current of the light emitting diode. The degradation induced at the forward current of the light emitting diode by X-rays irradiation is almost negligible whereas a decrease of the rate of change in current transfer ratio is significant during the X-ray irradiation. The results show that there is no significant difference between current transfer ratio of ON mode and OFF mode radiation. It is observed that the operating mode of the optoelectronic devices after exposure to 1000 mAs of X-ray irradiation contributes no major variation in the degree of damage.

Nonlinear properties of voltage and current transfer ratios for electric arc furnaces

A method of arc voltage gradient calculation for an electric arc furnace (EAF) is presented. The arc voltage gradient is the basic characteristic in study and simulation of an automatic power control system of an EAF. This characteristic is a strongly nonlinear multifactorial function that depends on electrical parameters of a power supply system, thermal conditions, and processes of arc heat exchange in an EAF melting bath. The method of arc voltage gradient calculation considers the relation between the electric and thermal conditions of an EAF in order to describe feasible nonlinear properties and to improve expressions for voltage and current transfer ratios as nonlinear multifactorial functions in particular. An EAF is regarded as a subject of control. Multifactorial properties are defined by the parameters of an equivalent electrical circuit of a furnace and by variable conditions of arc heat exchange in a melting chamber during steel melting. The method is effective for overcoming the uncertainty of the arc length in simulation of an EAR power controller. The unstable behavior of the furnace at a high impedance was explained using the obtained functions of the arc current and the arc voltage for various electrodes and the arc length. The minimum allowed arc current was found. The automatic power controller becomes unstable and the arc is extinguished under this value.

High-performance organic–inorganic hybrid optocouplers based on organic light-emitting diodes and a-Si:H photodiodes

Organic–inorganic hybrid electronics have attracted considerable attention because of the possibility of combining advantages of both the organic and inorganic devices. High-performance hybrid optocouplers made of the a-Si:H pin photodiode and organic light emitting diodes have been fabricated and studied. With a blue organic light emitting diode as the light source, the optocoupler shows good photoresponse with a current transfer ratio of 3.72% at the photodetector bias of −2V and a large light/dark current ratio of 5.6×106. With a high efficiency tandem white organic light emitting diode as the light source, an even higher current transfer ratio of 10.7% was achieved, which is larger than that of the all-organic optocoupler and is comparable to that of the all-inorganic optocoupler. Influences of different wavelength components ratios of the OLED spectrum on the photoresponse of a-Si:H pin photodiode was also investigated. It shows that the selection of OLED wavelength plays important roles in improving the performance of OOC. This kind of organic–inorganic hybrid system can be used in many electronic and optoelectronic products.

Organic optocoupler consisting of an optimized blue organic light emitting diode and an organic photoconductor

We present an optocoupler device based on a blue organic light-emitting diode (OLED) as input unit, and a pentacene photoconductor as output unit. The optocoupler was realized on a transparent glass substrate. The luminance was found larger than 103cd/m2 with a blue peak emission at 450nm for the optimized ZnO (120nm)/ITO (150nm)/α-NPB (40nm)/BCP (15nm)/Alq3 (20nm)/Al structure. The Ids-Illum/Ids-Dark current ratio, the sensitivity and the current density transfer ratio of the optocoupler are of about 7, 10−1A/W, and 10−1, respectively. The rise as well as full times were found faster for high bias voltages. The equilibrium regime with less persistent current was reached more quickly, as evidenced by the fast current response for higher bias voltage, indicating a more favorable recombination processes of the charge carriers. The organic optocoupler with a blue OLED reveals promising results; thus, it can be investigated as a good candidates for practical uses in organic optoelectronic circuits with high bias voltages.

Application of cascode level shifter for EMI reduction in LCD driver IC

Purpose – This paper aims to design the circuit for electromagnetic interface (EMI) reduction in liquid crystal display (LCD). Design/methodology/approach – The cascode level shifter and segmented driver circuit are applied in LCD column driver integrated circuit (IC) for EMI reduction. Cascode current mirror is used in the proposed level shifter for DC voltage biasing and reduction of the driving current which passes through the level shifter. The on-off switching currents and transient times are measured and compared between the conventional and proposed level shifters. Additionally, a segmented data latch is obtained by the timing spread solution in data latch, and applied to split the large peak switching current into a number of smaller peak current. The timing spread-operation does not actually reduce the total power of the noise, instead, it spreads the noise power evenly over the frequency bandwidth. The optimal number of latch is dependent on the operating frequency and EMI allowance. The column driver IC and clock controller are integrated in 0.18 μm CMOS technology with 1-poly and 4-metal process. Findings – The post-layout simulation shows that the proposed column driver circuit for LCD driver IC significantly reduces the peak switching current, and it results in the reduction of EMI noise level by more than 15 dB. It is obtained with 20 segmented operations in data latch at 40 MHz frequency. Originality/value – The advantage of the cascode current source is that it can provide a well-controlled bias current with an accurate current transfer ratio. To reduce the EMI noise in LCD driver circuit, the cascode current source is properly located for the DC bias block in the level shifter. The application is rarely done by others, and a significant EMI noise reduction is found. The well-controlled current source provides a high performance switching in the level shifter.