In described examples of a ramp circuit, a first terminal of a capacitor is coupled to a ramp terminal and a second capacitor terminal is coupled to a return terminal. A charge source has an input terminal coupled to a supply terminal and a charge output terminal. A resistor has a first terminal coupled to the return terminal. A first switch is coupled between the ramp terminal and a second terminal of the resistor. A second switch is coupled between the charge output terminal and the ramp terminal.

A ramp generator providing ramp signal with high resolution fine gain includes a current mirror having a first and second paths to conduct a capacitor current and an integrator current responsive to the capacitor current. First and second switched capacitor circuits are coupled to the first path. A fractional divider circuit is coupled to receive a clock signal to generate in response to an adjustable fractional divider ratio K a switched capacitor control signal that oscillates between first and second states to control the first and second switched capacitor circuits. The first and second switched capacitor circuits are coupled to be alternatingly charged by the capacitor current and discharged in response to each the switched capacitor control signal. An integrator coupled is to the second path to generate the ramp signal in response to the integrator current.

A microwave generator includes a power supply, an output circuit, a feedback oscillator, a pulse controller, a signal combination circuit and a semiconductor amplifier. The power supply converts input voltage and input current into output voltage and output current. The output circuit generates a microwave signal to an output terminal of the microwave generator and a feedback signal according to the microwave signal. The feedback oscillator generates an oscillation signal according to the feedback signal. According to a reference signal, the pulse controller generates a pulse signal. According to the oscillation signal and pulse signal, the signal combination circuit generates a control signal. The semiconductor amplifier generates and adjusts an amplified signal according to the control signal. The output circuit generates the microwave signal according to the amplified signal. The output current is adjusted according to the amplified signal. Consequently, the input current and the input voltage are in phase.

A class D amplifier circuit receives an analog audio signal with a first reference voltage as its center level, and outputs an output pulse signal having a duty cycle that corresponds to the analog audio signal. A bias circuit generates a second reference voltage having a voltage level obtained as a division of the first reference voltage and the power supply voltage. A periodic voltage generating circuit of the class D amplifier circuit generates a periodic voltage having a triangle waveform or otherwise a sawtooth waveform having an amplitude that corresponds to the second reference voltage.

A class D amplifier circuit receives an analog audio signal with a first reference voltage as its center level, and outputs an output pulse signal having a duty cycle that corresponds to the analog audio signal. A bias circuit generates a second reference voltage having a voltage level obtained as a division of the first reference voltage and the power supply voltage. A periodic voltage generating circuit of the class D amplifier circuit generates a periodic voltage having a triangle waveform or otherwise a sawtooth waveform having an amplitude that corresponds to the second reference voltage.

The power supply control device includes a logic circuit for generating a pseudo switch voltage simulating a behavior of a switch voltage generated in the switch output stage, a filter unit that receives input of the pseudo switch voltage and the output voltage or a feedback voltage corresponding to the output voltage and generates a current sense signal simulating a behavior of the inductor current, and a feedback control unit that performs output feedback control of the switch output stage by using the current sense signal.

A ramp signal calibration device includes a ramp generator circuit, a detector circuitry, and a calibration circuit. The ramp generator circuit is configured to output a ramp signal according to a set signal and a calibration signal. The detector circuitry is configured to detect the ramp signal or at least one pulse signal associated with the ramp signal, in order to generate at least one control signal. The calibration circuit is configured to generate a calibration signal in response to the at least one control signal, in order to adjust at least one of a falling slope or a rising slope of the ramp signal, or to adjust a duty cycle of the at least one pulse signal.

A ramp signal calibration device includes a ramp generator circuit, a detector circuitry, and a calibration circuit. The ramp generator circuit is configured to output a ramp signal according to a set signal and a calibration signal. The detector circuitry is configured to detect the ramp signal or at least one pulse signal associated with the ramp signal, in order to generate at least one control signal. The calibration circuit is configured to generate a calibration signal in response to the at least one control signal, in order to adjust at least one of a falling slope or a rising slope of the ramp signal, or to adjust a duty cycle of the at least one pulse signal.

A power supplier circuit supplies a power signal to a codec of an audio apparatus. The power supplier circuit includes a random sequence generation circuit, a control circuit, and a power circuit. The random sequence generation circuit generates a random sequence. The control circuit outputs a first control signal according to the random sequence, a first reference signal, and the power signal. The power circuit generates the power signal according to the first control signal, such that the power signal is spread in response to the random sequence.

A power supplier circuit supplies a power signal to a codec of an audio apparatus. The power supplier circuit includes a random sequence generation circuit, a control circuit, and a power circuit. The random sequence generation circuit generates a random sequence. The control circuit outputs a first control signal according to the random sequence, a first reference signal, and the power signal. The power circuit generates the power signal according to the first control signal, such that the power signal is spread in response to the random sequence.