Wideband GFSK-Modulated Frequency Synthesizer Using Two-Point Delta-Sigma Modulation

• Main Authors: Kang-Chun Peng, 彭康峻
• Other Authors: Tzyy-Sheng Horng
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/61126998200909115958

博士 === 國立中山大學 === 電機工程學系研究所 === 93 === This dissertation presents a 2.4 GHz wideband GFSK-modulated frequency synthesizer using two-point delta-sigma modulation (TPDSM). The two bottlenecks in this design have been rigorously investigated. One bottleneck is the nonlinear performance of the phase-locked loop (PLL). The other one is the inherent gain and delay mismatch between the two modulation points. Both nonlinear and mismatch factors dominate the modulation accuracy in the closed PLL. The proposed formulation can successfully predict the dependencies of the modulation accuracy on both factors. The comparison of the averaged frequency deviation and frequency-shift -keying (FSK) error between theory and measurement shows excellent agreement. The modulated frequency synthesizer implemented in this study can achieve a 2.5 Mbps data rate as well as a 15 μs PLL stable time with only 2.2 % FSK error under good design and operating conditions.