Reduced complexity, high performance digital delta-sigma modulator for fractional-N frequency synthesis

This paper presents the design consideration of high order digital AZ modulators used as modulus controller for fractional-N frequency synthesizer. A third-order MASH structure (MASH 1-2) is designed and implemented which allows for the input to operate over 75% of the input adder capacity. The number of the output levels is reduced to two bits. The circuit was verified through simulation, ASIC implementation and exhibits high potential for a gigahertz range, low-powermonolithicCMOS frequency synthesizer.

• Type: Conference
• Year: 1999
• Where: ISCAS
• Authors: Lizhong Sun, Thierry Lepley, Franck Nozahic, Amaud Bellissant, Tad A. Kwasniewski, Bany Heim
• Keywords: Fractional-N Frequency Synthesizer, Frequency Synthesizer, Hardware, ISCAS 1999, Third-order Mash Structure