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High loop-filter-order sigma-delta-fractional-N frequency synthesizers for use in frequency-hopping-spread-spectrum communication-systems

: Christoffers, N.; Kokozinski, R.; Kolnsberg, S.; Hosticka, B.J.

ISCAS 2003. Proceedings of the 2003 IEEE International Symposium on Circuits and Systems. CD-ROM
Piscataway, NJ: IEEE, 2003
ISBN: 0-7803-7762-1
International Symposium on Circuits and Systems (ISCAS) <36, 2003, Bangkok>
Conference Paper
Fraunhofer IMS ()
Nebenbandaussendung; biquadratische Funktion; Schleifenfilter; Einschwingzeit; Frequenzgenerator; Phasenrauschen; aktives Filter

Frequency-hopping-spread-sprectrum wireless digital communication-systems impose stringent requirements on both phase noise and settling time of PLL based frequency synthesizers employed in receivers and transmitters. If a sigma-delta-fractional-N-Synthesizer is used either the reference frequency or the loop filter order must therefore be high. We theoretically investigate PLLs of higher order and find that the settling time of a sixth order PLL suitable for operation in a bluetooth transceiver can be as low as 7µs in spite of a reference frequency of 16MHz.