초록 ▼

A high-power PWM system with improved low-power performance and which includes an oscillator configured to provide a substantially periodic signal to a pulse-width modulator. The pulse-width modulator outputs a PWM signal, derived from the analog signal and the periodic signal, on the PWM output nod

A high-power PWM system with improved low-power performance and which includes an oscillator configured to provide a substantially periodic signal to a pulse-width modulator. The pulse-width modulator outputs a PWM signal, derived from the analog signal and the periodic signal, on the PWM output node to a high-power amplifier that can select from a number of power-supply voltages. The PWM system improves amplification accuracy at low input signal levels by selecting a reduced power-supply voltage. The pulse width of the PWM signal is increased proportional to the decrease in the power-supply voltage to maintain the gain factor of the system at low power.

대표청구항 ▼

[ What is claimed is:] [1.] An apparatus comprising:a pulse-width modulator which produces a PWM signal in response to a select signal;a power supply having a PWM signal input terminal which receives the PWM signal from the pulse-width modulator, and a voltage source including a first power-supply o

[ What is claimed is:] [1.] An apparatus comprising:a pulse-width modulator which produces a PWM signal in response to a select signal;a power supply having a PWM signal input terminal which receives the PWM signal from the pulse-width modulator, and a voltage source including a first power-supply output terminal, and a second power-supply output terminal, wherein the voltage source provides a first power-supply voltage on the first power-supply output terminal, and a second power-supply voltage on the second power-supply output terminal, the first and second power supply voltages having levels determined in accordance with the PWM signal; andan amplifier having an input terminal which receives an input signal, a first power-supply input terminal connected to the first power-supply output terminal, a second power-supply input terminal connected to the second power-supply output terminal, and a third power-supply input terminal which provides a third constant voltage, and an output terminal which produces an output signal proportional to the difference between the third constant voltage and at least one of the first and second power-supply voltages.