A Broadband Fine Step Frequency Source Circuit

Abstract

The present invention provides a broadband and small-step frequency source circuit. A small-step output signal with the frequency thereof to be hundreds of megahertz is outputted through the DDS, so that the small-step output signal of a voltage controlled oscillator is realized. A broadband frequency source circuit is realized through selecting the voltage controlled oscillator having the broadband characteristics. According to the technical scheme of the invention, an IQ mixer is adopted as an RF mixer. The IQ mixer is used for extracting the different signal of a local oscillator signal and an intermediate-frequency (IF) signal. Meanwhile, the sum signal of the local oscillator signal and the intermediate-frequency (IF) signal is extracted, and the suppression of the different signal on the local oscillator signal is over 20 dBc. Therefore, RF signals outputted by the IQ mixer can enter a digital phase detector without passing through an extremely narrow-band filter. Compared with a conventional DDS circuit, the circuit is low in debugging difficulty and extremely high in frequency accuracy is, and can be miniaturized.

Description

technical field [0001] The invention relates to a wide-band fine-step frequency source circuit, which belongs to the technical field of microwave circuits. Background technique [0002] With the continuous development of communication technology, broadband frequency sources hope to be compatible with fine-stepping characteristics while achieving broadband characteristics. At present, the implementation of broadband frequency basically adopts the combination of DDS and single digital loop or the combination of DDS circuit, mixing loop and switching filter components. The former technology cannot be compatible with fine stepping and high clutter suppression at the same time; For the two technologies, the power consumption and volume of the products are relatively large, which cannot meet the requirements of low power consumption and miniaturization in the field of communication today. SUMMARY OF THE INVENTION [0003] The technical problem solved by the present invention is...

AI Technical Summary

Problems solved by technology

[0003] The technical problem solved by the present invention is: to overcome the deficiencies in the prior art, a kind of broadband fine step frequency source circuit is proposed, by adding frequency multiplication filter module, DDS circuit, low-pass filter, amplifier, IQ mixer and 90 ° bridge, so that the DDS circuit outputs a fine-step output signal of several hundred megahertz to realize the fine-step output signal of the voltage-controlled oscillator. By configuring the frequency division ratio N in the digital phase detector to achieve broadband characteristics, it solves the problem of The disadvantage that the existing frequency source circuit cannot be miniaturized when realizing wideband output and fine step output at the same time

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