Effects of Oscillator Phase Noise on Frequency Delta Sigma Modulators with a High Oversampling Ratio for Sensor Applications

Koichi MAEZAWA  Masayuki MORI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E104-C   No.9   pp.463-466
Publication Date: 2021/09/01
Publicized: 2021/03/15
Online ISSN: 1745-1353
DOI: 10.1587/transele.2020ECS6026
Type of Manuscript: BRIEF PAPER
Category: Microwaves, Millimeter-Waves
Keyword: 
delta sigma modulation,  frequency delta sigma modulation,  phase noise,  microwave oscillator,  

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Summary: 
Frequency delta sigma modulation (FDSM) is a unique analog to digital conversion technique featuring large dynamic range with wide frequency band width. It can be used for high performance digital-output sensors, if the oscillator in the FDSM is replaced by a variable frequency oscillator whose frequency depends on a certain external physical quantity. One of the most important parameters governing the performance of these sensors is a phase noise of the oscillator. The phase noise is an essential error source in the FDSM, and it is quite important for this type of sensors because they use a high frequency oscillator and an extremely large oversampling ratio. In this paper, we will discuss the quantitative effects of the phase noise on the FDSM output on the basis of a simple model. The model was validated with experiments for three types of oscillators.