Radioengineering (Jun 2004)
Frequency Stability Improvement in Direct Digital Frequency Synthesis
Abstract
The paper describes a digital frequency synthesizer thatincorporates a novel method of the clock signal frequency versustemperature dependency compensation. The clock signal is deriveddirectly from a dual mode crystal oscillator (DMXO). With introducingthe method, synthesized signal frequency versus temperature instabilitybelow a0.15ppm can be obtained over a wide temperature range (between45°C and +85°C). Since a temperature information is obtaineddirectly from a crystal itself rather than from an external sensor,temperature offset and lag effects are eliminated.
