0303846 - URE-Y 20010092 RIV US eng C - Conference Paper (international conference)
Kroupa, Věnceslav František - Štursa, Jarmil - Čížek, Václav - Švandová, Hana
Direct digital frequency synthesizers with the sigma-delta arranxgement in the PLL systems.
Piscataway: IEEE, 2001. ISSN 1075-6787. In: Proceedings of the 2001 IEEE International Frequency Control Symposium & PDA Exhibition., s. 799-805
[IEEE International Frequency Control Symposium. Seattle (US), 06.06.2001-08.06.2001 (K)]
R&D Projects: GA ČR GA102/00/0958
Institutional research plan: CEZ:AV0Z2067918
Keywords : frequency synthesizers * phase locked loops
Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Ten years ago DDS-PPL Fractional-N Frequency Synthesizers with additional feedback path circuits, behaving as Sigma-Delta modulator, were introduced. With the assistance of the z-transform and after introduction of several additional circuits with time delays the expected output frequency noise was computed to be proportional to (-z_-)₃. Since the phase noise is integral of the frequency noise, the slope of the power spectral density of the phase noise has been assumed to be 40 dB/decade. This conclusion was verified with the assistance complicated bench work. Recently these systems find applications in commercial communications.
Permanent Link: http://hdl.handle.net/11104/0114030