A versatile controller architecture, used in current-mode floating buck converters for LED driving, is developed. State-of-the-art controllers rely on a fixed switching period and variable duty cycle, focusing current averaging circuits. Instead, the proposed architecture based peak adaptable off time as average control method. The loop comprised of an block, transconductance amplifier, innovative modulator. This modulator intended to provide constant response regardless input voltage,...

In this paper, a characterization technique for 4H-SiC Schottky diodes with varying levels of metal-semiconductor contact inhomogeneity is proposed. A macro-model, suitable high-temperature evaluation SiC contacts, discrete barrier height non-uniformity, introduced in order to determine the temperature interval and bias domain where electrical behavior devices can be described by thermionic emission theory (has quasi-ideal performance). minimal set parameters, effective peff, non-uniformity...

Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by mixed barrier contact area and interface states. A simple analytical model that establishes quantitative correlation between parameter variation height non-uniformity is proposed. surface double considered. The main parameters are lower (ΦBn,l) p factor which quantitatively evaluates area. validated Ni/4H-SiC contacts, post metallization sintered at high...

This paper presents a high-temperature probe suitable for operating in harsh industrial applications as reliable alternative to low-lifespan conventional solutions, such thermocouples. The temperature sensing element is Schottky diode fabricated on 4H-SiC wafers, with Ni the metal, which allows operation at temperatures up 400 °C, sensitivities over 2 mV/°C and excellent linearity (R2 > 99.99%). also includes dedicated circuitry signal acquisition conversion 4 mA–20 mA standard output...

SiC devices' electrical properties used as sensing mechanisms are demonstrated for two types of sensors. A Schottky barrier diode (SBD) is proposed a temperature sensor while MOS capacitor gas (hydrogen) detection. layout with different active contacts, having 200, 300 and 400μm diameters similar technology designed fabricating both An automatic high system developed to test the sensors up 450°C. The main parameters devices operate extracted using dedicated programs. detection sensitivity...

A SiC Schottky dual-diode temperature-sensing element, suitable for both complementary variation of VF with absolute temperature (CTAT) and differential proportional to (PTAT) sensors, is demonstrated over 60–700 K, currently the widest range reported. The structure’s layout places two identical diodes in close, symmetrical proximity. stable high-barrier contact based on Ni, annealed at 750 °C, used. XRD analysis evinced even distribution Ni2Si entire area. Forward measurements K indicate...

A partially electrically isolated package with a gold wire and fully solution metallic piston, respectively, are designed tested for high temperature sensors (400°C) based on SiC Schottky barrier diodes (SBD). Electrical behavior sensor performance very close both packaging solutions. The stress due to contact pressure higher cost some disadvantages technology.

This paper evaluates the non-uniformity degree of platinum and chromium Schottky contacts on silicon carbide. The forward characteristics experimental samples were acquired in a wide, 60–500 K, temperature range. Microstructural conventional electrical characterizations performed, revealing presence inhomogeneities contact surface. main parameters extracted using inhomogeneity models varying complexity levels. Their relevance is discussed with respect to models’ applicable, limited, ranges....

A practical model, adequate for full reproduction of inhomogeneous Schottky diodes' forward characteristics over wide high-temperature and bias ranges, is proposed. According to this p-diode the contact current considered flow through m parallel-connected internal diodes, each with stable, constant barrier height specific series resistance (both main model parameters). The value m, required reproduce entire electrical behavior a non-uniform contact, directly connected particular parameter (p...

Different characterization techniques have been used in order to evaluate the electrical behavior of Pt/SiC-Schottky diodes and determine their capability as temperature sensors. I-V characteristics for fabricated devices were measured up 400°C. Subsequent conventional parameter extraction evinced a barrier height increase with temperature, suggesting inhomogeneous contact formation. The energy activation method was carried out identify both effective non-uniformity ( p ). Despite severe...

An improvement in performance of 4H-SiC Schottky diodes using a Ni metal is proposed. The effects the and ohmic contacts' annealing process conditions are investigated through electrical characterization diodes. A thermal treatment at 800°C leads to devices with stable reproducible behavior. high temperature sensor based on these diode has been proved.

This paper proposes an adaptive soft-start technique which offers both dynamic overshoot protection at start-up and maximum current regulation during steady state. The circuit is included in a boost converter IC Controller manufactured 50V, 0.5μm CMOS technology tested via simulations measurements. A comparative study performed regarding converter's operation with without the proposed block. Results emphasize solution's ability to suppress overshoots reduce time. Moreover, measured time...

Temperature behavior of 4H-SiC MOS capacitor is investigated. A new layout with several active structures proposed. Measured C-V characteristics show good thermal stability up to 300 C. The main electrical parameters the structure have been extracted by measurements on wafer and encapsulated samples.

Interface state density (D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> ) at SiO xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /4H-SiC interfaces is investigated using capacitance-voltage (C-V) characterization. Two different measurement methods for D determination (both C-V temperatures in the range of 80-300K and high frequency (HF) vs quasi static (QS) characteristics) have been used. A significant reduction observed, almost...

The electrical behavior and stability of a temperature sensor based on 4H-SiC Schottky diodes using Ni 2 Si as contact, are investigated. ideality factor the barrier height were found to be strongly dependent post-annealing contact (which lead formation Si). A nearly ideal device, with approaching high value 1 . 7 eV , slight dependence, was obtained after an annealing at T = 800°C. This proves that is suitable for sensors, able reliably operate up 450°C Sensor sensitivity levels between...

Switch-mode power supplies have become the premier choice for LED backlighting applications. This paper introduces a new current-mode floating buck controller architecture, used driving constant current through string of LEDs. Unlike state-of-the-art controllers, this architecture is based on fixed peak and variable OFF time as control method. An innovative modulator added to provide feedback loop response regardless external components. The proposed designed, implemented in 0.5μm CMOS...

A solution for obtaining an exponential variation of time versus input voltage a time-modulating circuit is investigated, implemented and its performances are measured. Most circuits produce delay that linearly dependent on the voltage. This paper proposes new method controlling output by making it vary exponentially with especially useful in aplications where time-delay constantly modulated prior error amplifier.

Two architectures of a bandgap reference with CMOS operational amplifiers are investigated, implemented and compared. In order to reduce the dependence voltage temperature power supply, trimming technique is often used. We propose new method lowering variation, based on very low offset amplifier. amplifier schematics designed, simulated measured.

The technological flow similarities between two devices on silicon carbide, a Schottky diode and MOS capacitor, are presented. used as temperature hydrogen sensors, respectively. Both characterized up to high temperatures, 400°C for 300°C capacitor. Performed measurements demonstrate good forward voltage linearity with (Schottky diode) the absence of mobile oxide charges (MOS capacitor).

This paper proposes a method of characterizing silicon carbide Schottky diodes with inhomogeneous contacts in temperature sensing applications. Using the energy activation technique, intervals where effective barrier height is constant are determined. Unlike conventional which increases for diodes, has physical meaning and can be used sensor performance evaluation. The utility analysis confirmed on fabricated Ni/4H-SiC different annealing conditions degrees non-uniformity. good agreement...

Initial control loop conditions are essential in switching circuits where fault detection blocks present, order to avoid permanent triggers. Furthermore, multi-channel interference may affect circuit functionality and cause additional Error amplifiers aquire the difference between sensed reference signals output a correction voltage. We propose solution which ensures that initial voltage does not determine perpetual condition. The proposed is implemented current mode buck loop, delivers...

For proper operation in real industrial conditions, gas sensors require readout circuits which offer accuracy, noise robustness, energy efficiency and portability. We present an innovative, dedicated circuit with a phase locked loop (PLL) architecture for SiC-MOS capacitor sensors. A hydrogen detection system using this is designed, simulated, implemented tested. The PLL converts the MOS nonlinear small-signal capacitance (affected by hydrogen) into output voltage proportional to detected...