The delta-sigma converter is one of the high speed and resolution analog-to-digital modulators. Its implementation needs the low oversampling technique and the multi-bit D/A converter. The noise induced by the multi-b...The delta-sigma converter is one of the high speed and resolution analog-to-digital modulators. Its implementation needs the low oversampling technique and the multi-bit D/A converter. The noise induced by the multi-bit D/A converter becomes one of the key factors deteriorating the signal-to-noise rate of the delta-sigma A/D converter. A novel structure with signal unity transfunction, dynamic element matching(DEM) and noise-shaping is discussed. The method is investigated to design converter based on the proposed structure. The behavior simulation indicates that the structure and the design method are feasible.展开更多
We propose a passive compensation fiber-optic radio frequency（RF） transfer scheme with a nonsynchronized RF stable source during a round-trip time, which can avoid high-precision phase-locking and efficiently suppre...We propose a passive compensation fiber-optic radio frequency（RF） transfer scheme with a nonsynchronized RF stable source during a round-trip time, which can avoid high-precision phase-locking and efficiently suppress the effect of backscattering only using two wavelengths at the same time. A stable frequency signal is directly reproduced by frequency mixing at the remote site. The proposed scheme is validated by the experiment over a 40 km single mode fiber spool using nonsynchronized common commercial RF sources. The influence of the stability of nonsynchronized RF sources on the frequency transfer is investigated over different length fiber links.展开更多
基金National Natural Science Foundation of China(50677014)Doctoral Special Found of Ministry of Education(20060532016)+2 种基金Natural Science Foundation of Hunan Province(06JJ2024)Program for New CenturyExcellent Talents in University(NCET-04-0767)Found of Hunan Education depart ment(05C141)
文摘The delta-sigma converter is one of the high speed and resolution analog-to-digital modulators. Its implementation needs the low oversampling technique and the multi-bit D/A converter. The noise induced by the multi-bit D/A converter becomes one of the key factors deteriorating the signal-to-noise rate of the delta-sigma A/D converter. A novel structure with signal unity transfunction, dynamic element matching(DEM) and noise-shaping is discussed. The method is investigated to design converter based on the proposed structure. The behavior simulation indicates that the structure and the design method are feasible.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61627817 and 61535006)
文摘We propose a passive compensation fiber-optic radio frequency（RF） transfer scheme with a nonsynchronized RF stable source during a round-trip time, which can avoid high-precision phase-locking and efficiently suppress the effect of backscattering only using two wavelengths at the same time. A stable frequency signal is directly reproduced by frequency mixing at the remote site. The proposed scheme is validated by the experiment over a 40 km single mode fiber spool using nonsynchronized common commercial RF sources. The influence of the stability of nonsynchronized RF sources on the frequency transfer is investigated over different length fiber links.
