Abstract: A class-D amplifying system includes: a class-D amplifier circuit configured to convert an input signal to a switch control signal in pulse width modulation fashion, wherein the switch control signal controls switches to operate a first inductor and a second inductor, thus converting an input power to a positive output signal and a negative output signal which are complementary to each other, to thereby drive a load; and a power converter circuit, which generates a direct current (DC) power supply according to at least one of the positive output signal and the negative output signal, wherein the DC power supply supplies at least a portion of power to the class-D amplifier circuit.

Abstract: A class-D amplifier configured to adjust at least one input signal to at least one output signal. The class-D amplifier comprises: a loop filter, configured to receive the input signal; a PWM circuit, configured to generate at least one PWM signal; a summing circuit, coupled between an output of the loop filter and an input of the PWM circuit; an output circuit operating at a supply voltage, configured to generate the output signal responding to the PWM signal; and a supply voltage filter, configured to monitor the supply voltage to generate a filtered signal to the summing circuit. The summing circuit is configured to sum the output of the loop filter and the filtered signal to adjust a common-mode level of the input of the PWM circuit.

Abstract: A class-D amplifier configured to adjust at least one input signal to at least one output signal. The class-D amplifier comprises: a loop filter, configured to receive the input signal; a PWM circuit, configured to generate at least one PWM signal; a summing circuit, coupled between an output of the loop filter and an input of the PWM circuit; an output circuit operating at a supply voltage, configured to generate the output signal responding to the PWM signal; and a supply voltage filter, configured to monitor the supply voltage to generate a filtered signal to the summing circuit. The summing circuit is configured to sum the output of the loop filter and the filtered signal to adjust a common-mode level of the input of the PWM circuit.

Abstract: A class D power amplifier with novel design is provided. The amplifier includes an input stage, a periodic signal generator, a comparator, a power output stage, and a boost circuit. The input stage is coupled to a first supply voltage. The periodic signal generator generates a periodic signal and a reference signal. The power output stage is coupled to a second supply voltage. The boost circuit compares an output of the input stage with the reference signal, and thereby adjusts a value of the second supply voltage. The value of the second supply voltage is larger than a value of the first supply voltage. The reference signal is proportional to an amplitude of the periodic signal, and the amplitude of the periodic signal is determined by the value of the second supply voltage.

Abstract: An amplifier circuit with novel design is provided. The amplifier circuit includes an input stage, a resistor, an output stage, an intermediate stage and a gm circuit. The input stage is coupled to a first supply voltage, and is arranged to receive an input voltage and a feedback current. The resistor is coupled between the input voltage and the input stage. The output stage is coupled to a second supply voltage, and is arranged to provide an output voltage for driving a load. The intermediate stage is coupled between the input stage and the output stage, and includes a level shifter. The gm circuit is coupled to the input stage, and is arranged to compare the input voltage with a common mode voltage, and thereby generates a compensate current for the input stage.

Abstract: An amplifier circuit with novel design is provided. The amplifier circuit includes an input stage, a resistor, an output stage, an intermediate stage and a gm circuit. The input stage is coupled to a first supply voltage, and is arranged to receive an input voltage and a feedback current. The resistor is coupled between the input voltage and the input stage. The output stage is coupled to a second supply voltage, and is arranged to provide an output voltage for driving a load. The intermediate stage is coupled between the input stage and the output stage, and includes a level shifter. The gm circuit is coupled to the input stage, and is arranged to compare the input voltage with a common mode voltage, and thereby generates a compensate current for the input stage.

Abstract: A voltage adjusting circuit includes a reference voltage generating circuit, a subtractor circuit, a threshold generating circuit and a comparator circuit. The voltage adjusting circuit may provide power supply signals to an amplifier circuit so that the amplifier circuit may provide an output signal to a load according to an input signal. The subtractor circuit generates a difference signal according to the output signal and the power supply signal. The comparator circuit compares the difference signal and a threshold signal generated by the threshold generating circuit for configuring the reference voltage generating circuit to adjust the signal value of the power supply signal.

Abstract: A voltage adjusting circuit includes a reference voltage generating circuit, a subtractor circuit, a threshold generating circuit and a comparator circuit. The voltage adjusting circuit may provide power supply signals to an amplifier circuit so that the amplifier circuit may provide an output signal to a load according to an input signal. The subtractor circuit generates a difference signal according to the output signal and the power supply signal. The comparator circuit compares the difference signal and a threshold signal generated by the threshold generating circuit for configuring the reference voltage generating circuit to adjust the signal value of the power supply signal.

Abstract: A class-D amplifier includes a ramp generator to provide a ramp signal having a frequency varying with an audio input signal, and a modulator to convert the audio input signal to a pulse width modulation signal according to the ramp signal for a driver to drive a load device. The varying frequency of the ramp signal will cause the frequency of the pulse width modulation signal unfixed and consequently improves EMI issue.

Abstract: A switching amplifier has a network including current sources and resistors connected to the two output terminals of the H-bridge of the switching amplifier, to provide a small current to the load connected between the two output terminals at zero input, whereby the common mode voltage bouncing is reduced and the switching amplifier has less power consumption and reduced electro-magnetic interference.

Abstract: A class-D amplifier includes a ramp generator to provide a ramp signal having a frequency varying with an audio input signal, and a modulator to convert the audio input signal to a pulse width modulation signal according to the ramp signal for a driver to drive a load device. The varying frequency of the ramp signal will cause the frequency of the pulse width modulation signal unfixed and consequently improves EMI issue.

Abstract: In a class-D amplifier, the input signal is compared with a carrier signal to generate a basic PWM signal, the PWM signal is then sent to a pulse processing unit, and by comparing with a basic periodic signal, half-width of the output PWM signal is extracted. Then, in the pulse processing unit, the half-width PWM pulse signal is used to generate a complete pulse whose width equals to the output PWM signal. The output power of the class-D amplifier can be kept as large as that by using differential input signals although the input signal is single-end and the entire signal processing path is kept single-ended.

Abstract: A switching amplifier has a network including current sources and resistors connected to the two output terminals of the H-bridge of the switching amplifier, to provide a small current to the load connected between the two output terminals at zero input, whereby the common mode voltage bouncing is reduced and the switching amplifier has less power consumption and reduced electro-magnetic interference.

Abstract: In a class-D amplifier, the input signal is compared with a carrier signal to generate a basic PWM signal, the PWM signal is then sent to a pulse processing unit, and by comparing with a basic periodic signal, half-width of the output PWM signal is extracted. Then, in the pulse processing unit, the half-width PWM pulse signal is used to generate a complete pulse whose width equals to the output PWM signal. The output power of the class-D amplifier can be kept as large as that by using differential input signals although the input signal is single-end and the entire signal processing path is kept single-ended.