Linear RF amplifier having reduced intermodulation distortion
US5528196A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 1995 |
| Grant date | Jun 18, 1996 |
| Priority date | — |
| Expiry date | Jan 6, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2201/3212
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A first loop is provided to subtract a properly scaled and delayed sample of the amplifier's input spectrum from a scaled and phase shifted sample of its output spectrum which contains intermodulation distortion. The result of this subtraction (if the samples are maintained at the same amplitude and 180 degrees out of phase) is a signal rich in the intermodulation products of the amplifier. A feature of the invention is a differential phase-amplifier comparator which compares the signals prior to and after amplification and generates control signals for amplitude and phase trimmers for the signal prior to the amplifier and thus maintains the required equal amplitude and 180 degree phase relationship required for carrier cancellation. The signals before amplification and after amplification are subtracted leaving substantially the intermodulation products resulting from amplification. A second loop is provided to reduce intermodulation distortion when a plurality of signals are amplified, resulting in the intermodulation of the signals. The intermodulation products are then fed forward with suitable amplification by an error amplifier and phase shift to cancel the amplifier intermod…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.