Issc Technologies Corp.

Microchip Technology Inc.

Yi-Lung Chen

Hsin-Chieh Huang

An audio amplifier apparatus for driving a loudspeaker is provided. The audio amplifier apparatus includes a soft charge unit, a first amplification module, and a second amplification module. The soft charge unit is coupled to the loudspeaker through an output terminal and supplies a driving current according to a first control signal to soft charge the loudspeaker, so as to gradually increase a voltage level on the output terminal. The first amplification module receives an audio signal according to the first control signal and amplifies the audio signal to output a first amplified signal for driving the loudspeaker. The second amplification module receives the audio signal according to a second control signal and amplifies the audio signal to output a second amplified signal for driving the loudspeaker. The soft charge unit generates the second control signal by comparing the voltage level on the output terminal with a predetermined voltage level.

Audio amplifier apparatus

A charge pump circuit and a phase lock loop circuit (PLL) having the same are provided. A main voltage divider and an assistant voltage divider configured in the charge pump circuit generate a voltage division within a predetermined time of activating the charge pump circuit. Therefore, when the charge pump circuit initiates operating, a voltage of a control end of a main switch set configured in the charge pump circuit is set to be the voltage division. The voltage of the control end is gradually decreased from the voltage division to a stable voltage according to a first current and a second current flowing through the main switch set. Accordingly, it can decrease the time from initiating operation of the pump circuit to stabilizing the voltage of the control end, thereby it can increase the working efficiency of the PLL.

Charge pump circuit and phase lock loop circuit having the same

A low dropout voltage regulator is provided. The low dropout voltage regulator includes a comparison unit, a buck unit, a feedback unit and a current-drawing unit. The comparison unit is used for receiving a reference voltage and a feedback voltage, and comparing the reference voltage and the feedback voltage to output a first voltage. The buck unit is used for receiving an input voltage and the first voltage and transferring the input voltage to a output voltage. The feedback unit is used for receiving the output voltage, and converting the output voltage to a feedback voltage, and then transmitting the feedback voltage to the comparison unit. The current-drawing unit determines whether to draw a portion of a first current generated by the buck unit, so as to stabilize the output voltage.

Low dropout voltage regulator and electronic device thereof

A voltage generating apparatus is provided. The voltage generating apparatus includes a reference voltage generator and an output voltage generator. The reference voltage generator is used for generating a reference voltage, and the reference voltage generator decides to generate the reference voltage or not according to a control signal. The output voltage generator includes a comparator, a variable resistor and a current source. The comparator compares the reference voltage and an output voltage to generator a calibrating signal. A resistance of the variable resistor is decided by the calibrating signal. The current source provides an output current to flow through the variable resistor for generating the output voltage. Wherein, the reference voltage is generated during an initial timing period, and the generator is turned off after the initial timing period. The initial timing period is determined according to the control signal.

Voltage generating apparatus

The voltage generator provided by the present invention includes: a first current source, a second current source, a first resistor, a reference voltage generator, a first amplifier and a second amplifier. The first current source generates a first current and a second current with a first temperature coefficient according to a first bias voltage. The second current source generates a third current and a fourth current with a second temperature coefficient according to a second bias voltage. The reference voltage generator provides a first reference voltage and a second reference voltage according to the first and third currents. The first amplifier generates the first bias voltage according to the first and second reference voltages. The second amplifier generates the second bias voltage according to the second and third reference voltages. Wherein, the first temperature coefficient and the second temperature coefficient are complementary.

Voltage generator

A power on reset signal generating apparatus is provided. The power on reset signal generating apparatus includes a trigger capacitor, a reference current supplying circuit, and a current regulator. One end of the trigger capacitor is coupled to a ground voltage, and the other end of the trigger capacitor generates a power on reset signal. The reference current supplying circuit is coupled to a signal generating end. The current regulator is coupled to the signal generating end, and the signal generating end draws a splitting current to adjust the value of the current received by the trigger capacitor.

Power on reset signal generating apparatus and method

An oscillator is provided and includes a resistance unit, a capacitance unit, a first inverter and a second inverter. The resistance unit is serially connected between a first reference point and a second reference point. The capacitance unit is coupled between the first reference point and an output point, and includes capacitors. One terminal of each of the capacitors is coupled to the output point, and the other terminal of each of the capacitors is coupled to the first reference point or a reference ground according to a control signal. The input terminal of the first inverter is coupled to the first reference point, and the output terminal of the first inverter is coupled to the second reference point. The input terminal of the second inverter is coupled to the output terminal of the first inverter, and the output terminal of the second inverter is coupled to the output point.

Oscillator for generating output signal with adjustable frequency

A circuit used for indicating process corner and extreme temperature mainly comprises a proportional to absolute temperature (PTAT) current source, a negative to absolute temperature (NTAT) current source, a constant to absolute temperature (CTAT) current source, a corner detector, a poly detector, an extreme temperature detector. The circuit can improve more power consumption without trade-off. In debug phase, the circuit can read out a state of a suspect sample and can run simulation check quickly to identify the real problem. In production phase, the circuit can easily read out at a processing station. In the mean time, a large quantity of data can be easily collected and analyzed.

Circuit used for indicating process corner and extreme temperature

The present invention provides a dual mode sigma delta analog to digital converter (ADC), which only in one hardware implementation, used for low IF and near zero IF receiver. The dual mode sigma delta ADC comprises a first switched-capacitor integrator; a second switched-capacitor integrator; a quantizer; a feedback circuit and a mode device. By switching the mode device on or off, one could easily change the configuration of the disclosed ADC to decide the receiving signal falling in low-IF or near zero IF.

Dual mode sigma delta analog to digital converter and circuit using the same

The present invention discloses a circuit with three-stage of power-on sequence used for suppressing the pop noise in audio system. It mainly comprises a first resistor (R); a capacitor (C); a first switch (SW); a second switch (SW); a soft start device; a first feedback amplifier; and a second feedback amplifier. By using the three-stage of power-on sequence, the present invention can effectively suppress the pop noise when the audio driver is power on.

Circuit with three-stage of power-on sequence used for suppressing the pop noise in audio system

The present invention discloses a two-step VCO calibration method. The two-step VCO calibration method, comprising power-on calibration, used to provide a coarse VCO tuning; real-time calibration, used to provide a fine VCO tuning according to the loaded result of said power-on calibration. The two-step VCO calibration method according to the present invention can cover all the variation of process and temperature and gain the advantages of shorter calibration time, smaller gain of VCO, pretty smaller size of passive loop filter and less operating power consumption.

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Keelung, Taiwan

Yi-Lung Chen