Frequency synthesizer and frequency synthesis method for converting spurious tone to noise

Abstract

The invention provides a frequency synthesizer and a frequency synthesis method for converting a spurious tone to noise. One of the advantages of a direct frequency synthesis technology (such as flying-adder architecture) is that the technology produces arbitrarily variable frequencies through the concept of time average frequency. At an output end of the frequency synthesized by direct frequency, a period with a single type is replaced by a period with two types. Different from a traditional frequency with the period with a single type, wherein the frequency energy is focused on the design frequency, a frequency based on time average frequency spreads a part of the energy to the spurious tone that may be harmful in some application. The spurious tone is resulted from the periodic carrysequence of a fraction adder in the frequency synthesizer. The invention provides the method and the device to break the periodicity and to convert the spurious tone to wide band noise.

Description

technical field [0001] The present invention relates to a frequency synthesizer and a frequency synthesis method, and in particular to a frequency synthesizer and a frequency synthesis method capable of converting spurious tone into noise. Background technique [0002] A frequency synthesizer can provide an accurate and stable frequency source in a frequency range, which is commonly found in modern electronic devices such as radio receivers, mobile phones, satellite receivers or global positioning systems. Frequency synthesis techniques include direct frequency synthesis and indirect frequency synthesis. Among them, direct frequency synthesis technology includes direct digital pulse rate (direct digital pulse rate) and fast accumulator (flying-adder) architecture, etc., which has the advantages of fast frequency change speed and can generate any variable frequency. However, it is easy to generate Excessive spurs lead to unwanted spurious tones in the spectrum of an output s...

AI Technical Summary

Problems solved by technology

In addition, in order to keep the output frequency unchanged, the overall average value of random numbers must be zero, so it is necessary to use a signed number system in circuit design, which increases system complexity and cost

Furthermore, in the high-speed operation mode, a high-speed adder is required to add random numbers, which consumes a lot of hardware resources

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