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This article proposes an LED driver circuit which is wide-range continuous dimmable for high power lighting application. The proposed LED driver is based on single-inductor–multiple-output (SIMO) dc–dc converter. A pulsewidth modulation (PWM) control strategy is applied on the LED driver to control the brightness of LEDs flexibly and precisely, with which the dimming frequency can be increased significantly, and the dimming ratio for all branches can be adjusted separately. PWM dimming would cause the inductor current overshooting when dimming switch alters from off to on, which makes the LED current varying. To suppress the inductor current overshooting, a sampling–holding circuit is adopted in the feedback loop of the proposed LED driver. A prototype of the proposed LED driver is fabricated and tested. The measurement results show that the dimming frequency can be increased to 10 kHz, the dimming ratio can be set from 5% to 100% with a minimum pulsewidth of 5  $\mu$ s, and the inductor current overshooting is suppressed from 150% to approximately 0%. The proposed LED driver can output more than 80 W and achieve a conversion efficiency of 97%. [ABSTRACT FROM AUTHOR]

A novel 4H-SiC multizone collector vertical insulated-gate bipolar transistor (MZC-IGBT) with an alternate P+/P−/P+ multizone structure in the collector region is proposed and investigated by numerical simulations in this article. Comparing with conventional 4H-SiC IGBTs, lower potential barrier regions are formed in the proposed MZC-IGBT at the interface between the N field-stop buffer and the collector region, modifying the carrier extraction effect to a proper level and resulting in a superior tradeoff between the static and dynamic performances. The proposed device consumes less energy in a wide frequency range. The numerical simulation reveals that the average dissipation power of the optimized 4H-SiC MZC-IGBT can be decreased by 63.1% at a high frequency of 20 kHz and even 2.26% at a low frequency of 500 Hz, which makes the proposed device much more suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

In this article, the breakdown voltage (${V}_{\text {BR}}$) shift of 4H-SiC Junction Barrier Schottky (JBS) diodes terminated by optimum nonequidistant field limiting rings (FLRs) subject to reverse-bias stress (RBS) has been investigated, and the corresponding mechanisms are studied in-depth. It can be observed that ${V}_{\text {BR}}$ gradually increases with increasing stress time, but there is no obvious shift of the forward voltage (${V}_{F}$). The increment in the magnitude of ${V}_{\text {BR}}$ induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of ${V}_{\text {BR}}$ shift has been investigated and explained by means of numerical technical computer-aided design (T-CAD) simulations. Our analysis shows that the hole injection and trapping into SiO2 at the FLR terminal area are identified to be the main cause, resulting in the increase of ${V}_{\text {BR}}$. Besides, a simple model is proposed to explain the behavior of ${V}_{\text {BR}}$ instability. [ABSTRACT FROM AUTHOR]

High-temperature storage stressing (HTSS) experiments were carried out on high-voltage 4H-SiC junction barrier Schottky (JBS) diodes. The effects of the high-temperature (up to 275 °C) storage under air environment on thermal stability of the 4H-SiC JBS are investigated. The electrical parameter shifts for tested diodes after the HTSS were investigated in detail, and related degradation mechanisms have been discussed. It is found that HTSS has no effect on the Schottky barrier height, the ideality factor (n), and specific on-resistance ( $R_{{\text{on-sp}}}$). However, it was interesting that the breakdown voltage ($V_{{\text{BR}}}$ ) of the devices was decreased first and then increased as the storage time increased. With the analysis of the SiO2/4H-SiC interface characteristics using metal-oxide-semiconductor structure fabricated simultaneously with the investigated 4H-SiC JBS on the same wafer and technical computer-aided design (T-CAD) simulations, trapped-electrons and holes located at the interface of SiO2/4H-SiC on termination region are identified to be the basic reason causing the degradation of reverse characteristics in the devices. [ABSTRACT FROM AUTHOR]