A Novel Three-Point Modulation Technique for Fractional-N Frequency Synthesizer Applications
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This paper presents a novel three-point modulation technique for fractional-N frequency synthesizer applications. Convention modulated fractional-N frequency synthesizers suffer from quantization noise, which degrades not only the phase noise performance but also the modulation quality. To solve this problem, this work proposes a three-point modulation technique, which not only cancels the quantization noise, but also markedly boosts the channel switching speed. Measurements reveal that the implemented 2.4 GHz fractional-N frequency synthesizer using three-point modulation can achieve a 2.5 Mbps GFSK data rate with an FSK error rate of only 1.4 %. The phase noise is approximately -98 dBc/Hz at a frequency offset of 100 kHz. The channel switching time is only 1.1 μs with a frequency step of 80 MHz. Comparing with conventional two-point modulation, the proposed three-point modulation greatly improves the FSK error rate, phase noise and channel switching time by about 10 %, 30 dB and 126 μs, respectively.
KeywordsFractional-N frequency synthesizer, delta-sigma, three-point modulation, phase-locked loop, GFSK
Document typePeer reviewed
Document versionFinal PDF
SourceRadioengineering. 2013, vol. 22, č. 1, s. 269-275. ISSN 1210-2512
- 2013/1