Frequency synthesizer for improving a unique DDS characteristic
AssigneeSamsung Electronics Co., Ltd.
InventorTakahiko Kishi
Life of this patent
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Abstract
A frequency synthesizer that improves a unique DDS characteristic, while maintaining a circuit scale (ROM size) of a direct digital synthesizer (DDS). A first digital signal generator generates a quantized frequency signal, and a second digital signal generator generates a frequency signal having a fine frequency resolution and many spurious signals as compared with the first digital signal generator. A filter performs band rejection on an output of the second digital signal generator, and a mixer mixes an output of the first digital signal generator with an output of the filter.
Claims12
A frequency synthesizer for a radio communication system, comprising:
- a first digital signal generator for generating a first frequency signal with a first output sampling frequency;
- a second digital signal generator for generating a second frequency signal with a second output sampling frequency having a fine frequency resolution and many spurious signals as compared with the first digital signal generator;
- a filter for performing band rejection on the second frequency signal of the second digital signal generator;
- and
- a mixer for mixing the first frequency signal of the first digital signal generator with an output of the filter;
- wherein the filter includes an interpolation filter for performing band rejection by equalizing the second output sampling frequency of the second digital signal generator to the first sampling frequency of the first digital signal generator.
Dependencies are inferred from the claim text.