US 6,803,798 B1 · Output control apparatus of pulse width modulator

Abstract

The invention provides an output control apparatus for adjusting the output level of a pulse width modulation (PWM) signal by changing the amplitude level of the output PWM signal. The output control apparatus comprises a control signal generator, a digital-to-analog converter (DAC), and an output circuit. The control signal generator generates a digital control signal. The DAC outputs a predetermined level according to the digital control signal. The output circuit with a negative feedback loop receives the PWM signal and receives the predetermined level by the negative feedback loop. While the PWM signal is logic number “0”, the negative feedback loop is not switched on, so as to control the level of the PWM signal at a base level. While the PWM signal is logic number “1”, the negative feedback loop is switched on, so as to control the level of the PWM signal at the predetermined level.

Claims20

Dependent claims

A control apparatus for controlling a level of a pulse width modulation signal (PWM signal) generated by a pulse width modulator (PWM), the apparatus comprising:

a control signal generator for generating a digital control signal;
a digital-to-analog converter (DAC) for outputting a predetermined level according to the digital control signal;
and
an output circuit with a negative feedback loop for
receiving the PWM signal, and receiving the predetermined level by the negative feedback loop;
while the PWM signal is logic number “0”, not switching on the negative feedback loop, so as to control the level of the PWM signal at a base level;
and
while the PWM signal is logic number “1”, switching on the negative feedback loop, so as to control the level of the PWM signal at the predetermined level.

5 more elements

An output control apparatus for controlling an output level of a PWM signal at a predetermined level, the output control apparatus comprising:

a set of differential inputs for differentially inputting the PWM signal;
a predetermined level input for providing a predetermined level;
a set of base level inputs for providing a base level;
a set of high level inputs for providing a highest level;
a set of differential level outputs for differentially outputting an output level of the PWM signal;
a switch combination comprising a plurality of switches for connecting to the set of differential inputs, the set of base level inputs, and the set of high level inputs;
and
an amplifier combination comprising a plurality of amplifiers, each amplifier connecting to a differential input of the set of differential inputs, a base level input of the set of base level inputs, a high level input of the set of high level inputs, and a differential level input of the set of differential level inputs, each the amplifier comprising:
an inverting input for inputting the predetermined level;
a non-inverting input for connecting to the differential level output;
and
an amplifier output for connecting to the switch combination;
wherein while the PWM signal is logic number “0”, the switch combination switches on the base level input and connects the amplifier output to the high level input to make the amplifier not be switched on, so as to control the level of the PWM signal at the base level;
and
while the PWM signal is logic number “1”, the switch combination doesn't switch on the base level input and connects the amplifier output to the level output to make the amplifier combination and the switch combination form a negative feedback loop, so as to control the level of the PWM signal at the predetermined level.

12 more elements

Dependencies are inferred from the claim text.

Output control apparatus of pulse width modulator

Life of this patent

Output control apparatus of pulse width modulator

Life of this patent

Abstract

Claims20