Digital compensation for wideband modulation of a phase locked loop frequency synthesizer
US6008703A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 1997 |
| Grant date | Dec 28, 1999 |
| Priority date | — |
| Expiry date | Jan 31, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2017
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital compensation filtering technique is provided that enables indirect phase locked loop modulation with a digital modulation data stream having a bandwidth that exceeds, perhaps by an order of magnitude, the bandwidth characteristic of the phase locked loop. A modulation data receiver is provided for receiving from a modulation source digital input modulation data having a bandwidth that exceeds the cutoff frequency characteristic of the phase locked loop frequency response. A digital processor is coupled to the modulation data receiver for digitally processing the input modulation data to amplify modulation data at frequencies higher than the phase locked loop cutoff frequency. This digital processor is connected to the phase locked loop frequency divider to modulate the divider based on the digitally-processed input modulation data, whereby a voltage controlled oscillator of the phase locked loop is controlled to produce a modulated output carrier signal having a modulation bandwidth that exceeds the phase locked loop cutoff frequency. The digital processing of the modulation data can be implemented by adapting a digital FIR Gaussian transmit filter such that its filter ch…
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