Elite Semiconductor Microelectronics Technology Inc.

Epistar Corporation

Yao-Wei Yang

Yu-Wei Kuo

Pei-Hsiang Tseng

Chien Cheng Huang

Kuo-Wei Yen

The oscillator includes a reference current generating circuit, a voltage modulator circuit, and an oscillating circuit. The reference current generating circuit is arranged to generate a reference current. The voltage modulator circuit is arranged to receive a feedback voltage, and perform a voltage modulation operation according to a first reference voltage and the feedback voltage, to generate a modulated voltage. The oscillating circuit is coupled to the reference current generating circuit and the voltage modulator circuit, and arranged to generate an oscillation signal with an oscillation frequency according to the reference current and the modulated voltage.

Oscillator that performs linear frequency modulation upon oscillation signal output to DC-to-DC converter under voltage mode

A bootstrap device used for first and second transistors of a buck-boost converter includes first and second bootstrap circuits. The first bootstrap circuit generates a first bootstrap voltage, and determines, based on a change among a first switching voltage, a voltage level of a source terminal of the first transistor and the first bootstrap voltage, whether to charge according to at least one of a DC input voltage, a DC output voltage, and a second bootstrap voltage. The second bootstrap circuit generates the second bootstrap voltage, and determines, based on a change among a second switching voltage, a voltage level of a source terminal of the second transistor, and the second bootstrap voltage, whether to charge according to at least one of the DC input voltage, the DC output voltage, and the first bootstrap voltage. The bootstrap device improves charging efficiency of bootstrap capacitors.

Bootstrap device and buck-boost converter

A voltage mode controlled linear frequency modulation oscillator comprises a voltage modulation circuit, a reference current generating circuit, and an oscillating circuit. The voltage modulation circuit is configured to generate a modulation voltage according to a feedback voltage and a first reference voltage. The reference current generating circuit, coupled to the voltage modulation circuit, is configured to generate a first reference current according to the modulation voltage and a second reference voltage. The oscillating circuit, coupled to the reference current generating circuit, is configured to generate an oscillating signal with an oscillating frequency according to the first reference current, wherein the oscillating frequency varies with the modulation voltage.

Voltage mode controlled linear frequency modulation oscillator

A linear charger includes a constant current charging circuit and a thermal regulation circuit. The constant current charging circuit is arranged to generate a charging current, and includes a first transconductance amplifier, wherein the first transconductance amplifier has a positive terminal, a negative terminal, and an output terminal. The thermal regulation circuit is coupled to the output terminal and the negative terminal of the first transconductance amplifier, and is arranged to generate and modulate a thermal regulation current and an amplifier reference voltage with temperature, and transmit the thermal regulation current and the amplifier reference voltage to the output terminal and the negative terminal of the first transconductance amplifier, respectively.

Linear charger with thermal regulation circuit

A control circuit for controlling a DC-DC converter is provided. The control circuit comprises a first sensor, second sensor, error amplifier, signal conditioning circuit, first comparison circuit, second comparison circuit, and driver circuit. The error amplifier is configured to receive a feedback voltage and a reference voltage for generating a first voltage. The signal conditioning circuit is configured to receive the first voltage for generating a second voltage and a third voltage. The first comparison circuit is configured to make a comparison based on a first sensing signal from the first sensor and the second voltage for generating a first comparison signal. The second comparison circuit is configured to make a comparison based on a second sensing signal from the second sensor and the third voltage for generating a second comparison signal. The driver circuit is for driving a power stage according to the first and second comparison signals.

Control circuit with automatic frequency modulation for DC-DC converter

A light emitting device includes: a plurality of light emitting stacked layers, including a first surface and a second surface, wherein the second surface is electrically opposite to the first surface; a mesa structure; a current blocking layer disposed on the first surface, including a sidewall; and a transparent conductive layer disposed on the first surface; and a first pad electrode, disposed on the transparent conductive layer and on the first surface; wherein a retract distance of the transparent conductive layer with respect to an edge of the mesa structure is less than 3 &#x3bc;m; and wherein a retract distance of the transparent conductive layer with respect to an edge of the sidewall of the current blocking layer is less than 3 &#x3bc;m.

Light emitting device

A light emitting device includes: a plurality of light emitting stacked layers, including a first surface and a second surface, wherein the second surface is electrically opposite to the first surface; a mesa structure; and a current blocking (CB) layer disposed on the first surface; a transparent conductive layer disposed on or above the first surface; and a first pad electrode, disposed on the transparent conductive layer and on the first surface; wherein a sidewall of the CB layer comprises a first surface section and a second surface section having different slopes.

A method for fabricating a light emitting device, comprising: forming a plurality of light emitting stacked layers above a substrate; forming and patterning a current blocking (CB) layer on the light emitting stacked layers; forming a transparent conductive layer covering the light emitting stacked layers and the current blocking layer; etching the transparent conductive layer and exposing a reserved region for a first pad electrode and a mesa structure, respectively; and etching an exposed portion of the light emitting stacked layers and a portion of the current blocking layer to form a remaining current blocking layer, the mesa structure and a first opening.

Method of manufacturing a light emitting device

A light emitting device, includes a substrate; a plurality of light emitting stacked layers, comprising a first surface and a second surface; a mesa structure; a current blocking (CB) layer; a transparent conductive layer; a first pad electrode and a second pad electrode; and a passivation layer, wherein the second surface is electrically opposite to the first surface, the transparent conductive layer is disposed on or above the first surface, the first pad electrode is disposed on the transparent conductive layer and on the first surface, and the second pad electrode is disposed on the second surface and on the mesa structure, the CB layer is disposed on the first surface, surrounded by the transparent conductive layer, and at a lower region of the first pad electrode, a portion of the first pad electrode is filling a first opening of the transparent conductive layer and the CB layer.

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Hsinchu, Taiwan

Yao-Wei Yang