Elite Semiconductor Microelectronics Technology Inc.

Elite Semiconductor Memory Technology, Inc

Tsinghua University

Che-Wei Hsu

Wun-Long Yu

Yun Chi

Chung-Hao Tseng

Deng-Yao Shih

Jia-Ling Liao

A driving circuit of a loudspeaker includes a periodic signal generation circuit, a signal processing circuit, a class-D amplifier circuit, a current sensing circuit, and a sample and hold circuit. The periodic signal generation circuit is arranged to generate a periodic signal and a control signal. The signal processing circuit is coupled to the periodic signal generation circuit, and is arranged to generate a pre-driving signal. The class-D amplifier circuit is coupled to the signal processing circuit, and is arranged to drive the loudspeaker according to the pre-driving signal. The current sensing circuit is coupled to the class-D amplifier circuit, and is arranged to generate a current sensing signal. The sample and hold circuit is coupled to the periodic signal generation circuit and the current sensing circuit, and is arranged to sample and hold the current sensing signal according to the control signal, to generate a current sampling signal.

Driving circuit of loudspeaker and method for generating current sampling signal of loudspeaker

An audio amplifier with duty ratio control is provided. The audio amplifier comprises a pulse width modulation modulator, a power stage, and a voltage converter. The pulse width modulation modulator is configured to receive an input signal for generating a pulse width modulation signal. The power stage is configured to output an output signal according to a supply voltage and the pulse width modulation signal. The voltage converter is configured to adjust voltage level of the supply voltage according to the pulse width modulation signal. The audio amplifier is configured to adjust the voltage level of the supply voltage when duty ratio of the pulse width modulation signal is greater than a duty ratio threshold.

Audio amplifier with duty ratio control

A COT (constant on-time) buck converter includes a first transistor, a second transistor, a driver circuit, an inductor, a first resistor, a second resistor, a capacitor, a load, and a feedback loop circuit. The feedback loop circuit includes a first switch, a second switch, an error amplifier, a comparator, a frequency locked loop circuit, an inverter and a COT logic circuit. The COT buck converter is able to improve DC (direct-current) regulation efficiency and transient response time.

Constant on-time buck converter with improved transient response

A boost class-D amplifier includes a PWM modulator, a boost level controller coupled to the PWM modulator, a pre-driver coupled to the PWM modulator and the boost level controller, a system voltage source, an inductor coupled to the system voltage source, a first switch, a second switch, a third switch, a fourth switch, a first diode coupled between the third switch and a voltage ground, a second diode coupled between the fourth switch and the voltage ground, and a capacitor coupled between the first switch and the fourth switch. The PWM modulator is for receiving an input signal and generating a first modulated signal accordingly. The boost level controller is for receiving the first modulated signal and generating a second modulated signal accordingly. The pre-driver is for receiving the first modulated signal and the second modulated signal and generating control signals accordingly.

Single-stage boost class-D amplifier

A constant on-time controller (COT) includes: a voltage dividing circuit to generate a feedback voltage according to an output voltage of a buck regulator; a current ripple extracting circuit to sense a current from an inductor of a buck regulator, and generate an extracted ripple current having no DC component according to a sensed current; a one-shot on-timer to output a constant-on time control signal according to a regulator input voltage of the buck regulator and the output voltage; a comparing circuit to output a comparison result according to a reference voltage signal, the feedback voltage and the extracted ripple current; and a logic circuit to generate a control signal to the buck regulator according to the comparison result and the constant-on time control signal. The current ripple extracting circuit detects the DC component in the present cycle, and compares the detected DC component with the next cycle.

Constant on-time controller and buck regulator device using the same

A power control circuit includes an alternating current (AC) power source, a rectifier and a valley-fill circuit. The AC power source is configured to receive an AC voltage. The rectifier is configured to convert the AC voltage into a rectified voltage. The valley-fill circuit includes: an inductor, having a first terminal coupled to the rectifier, and a second terminal; a first resistor, having a first terminal coupled to the second terminal of the inductor, and a second terminal; a diode, having a cathode coupled to the second terminal of the inductor, and an anode; and a first capacitor, having a first terminal coupled to the second terminal of the first resistor and the anode of the diode, and a second terminal coupled to ground.

Valley-fill PFC circuit with EMI protection

A platinum complex having at least one carbene fragment, and an OLED using the same are described. The platinum complex contains a platinum cation, a zero-valent nitrogen-containing heterocyclic bidentate chelate, and a dianionic nitrogen-containing heterocyclic bidentate chelate. The zero-valent nitrogen-containing heterocyclic bidentate chelate has at least one carbene unit coordinating to platinum. The dianionic nitrogen-containing heterocyclic bidentate chelate has at least one electron-withdrawing substituent, and forms two N&#x2014;Pt bonds, or one N&#x2014;Pt bond and one C&#x2014;Pt bond, with the central platinum cation.

Growing community of inventors

Hsinchu, Taiwan

Che-Wei Hsu