Audio amplifier with phase modulated pulse width modulation
US4992751A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 17, 1989 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | Oct 17, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/2171
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a digitally controlled amplifier circuit a dc power source is modulated by an oscillator signal for producing a reference square wave signal. A sawtooth signal, double the frequency of the reference signal and synchronized therewith, is compared with a variable input signal to be amplified. When the sawtooth exceeds the input signal a phase shifted version of the reference signal, shifted in phase in accord with the instantaneous amplitude of the variable signal is produced. A switching circuit logically governed by the reference and phase shifted signals produce a pulse width modulated output signal of a selected polarity. An output filter smooths the pulse width modulated output signal and steering diodes control the polarity of the switching circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.