Dual mode class D amplifiers
US6587670B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 29, 1999 |
| Grant date | Jul 1, 2003 |
| Priority date | — |
| Expiry date | Jun 29, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/2171
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Pulse width modulated (“Class D”) amplifiers and controllers switching in the 50 khz to 2 MHz range generate harmonics which interfere with AM radio reception. This has precluded wide spread acceptance of class D amplifiers in products with an AM radio. The amplifiers described here use a modified modulation technique when operating with an AM radio to avoid generating harmonics at the receiver selected frequency or its intermediate (IF) frequency. One embodiment uses a harmonic avoidance modulator. A second embodiment uses two or more oscillators and tests for the least distorted output signal. A third embodiment switches the mode of operation to a class AB amplifier when an AM signal is amplified.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.