Broadband preselection mixer design method

Abstract

The invention provides a broadband preselection mixer design method. Through preferable ferrite harmonic oscillator of a preselector and by utilizing high-saturation magnetization intensity characteristic of a NZF ball to broaden the passband bandwidth, the 3dB bandwidth can reach 300 MHz-500MHz. By adopting the above scheme, the influence of preselector passband offset on overall performances of a frequency spectrograph due to the inherent characteristics, such as hysteresis lag, temperature drift, and tuning nonlinearity and the like, of a magnetic device is effectively reduced; by adopting optimization coupling structure and magnetic circuit design and the like methods, the frequency range of the preselector is broadened to be 26.5 GHz-50 GHz; high and low local oscillator schemes are applied simultaneously, the design difficulty of a local oscillator Balun is reduced; a double-balanced mixer with third harmonic frequency mixing covering full waveband is established, and finally a broadband preselection mixer, of which the frequency range covers 26.5 GHz-50 GHz is designed.

Description

technical field [0001] The invention belongs to the technical field of design methods for broadband preselection mixers, and in particular relates to a design method for 50GHz broadband preselection mixers based on NZF ferrite filter technology. Background technique [0002] Among modern electronic measuring instruments, the spectrum analyzer is an important tool for signal frequency domain analysis, which is equivalent to a microwave multimeter. It is widely used in microwave communication, radar, navigation, electronic countermeasures, EMC testing and other fields. An essential measuring instrument. A modern broadband spectrum analyzer is a microprocessor-controlled sweeping receiver. Most of the front-end designs use superheterodyne schemes, using front-end pre-selection, harmonic mixing and other technologies. The front-end pre-selector tunes the pre-selected signal under the control of the system, effectively minimizes image and multiple responses. Ferrite magneticall...

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Problems solved by technology

[0008] Through the analysis of references and products at home and abroad, the existing domestic microwave and millimeter wave frequency band filter mixers use LAF ferrite resonators, and the passband bandwidth is narrow. When the whole machine is quickly scanned and tested, the hysteresis of the filter mixer Factors such as temperature drift, tuning nonlinearity and other factors will affect the test accuracy, and the higher the frequency, the more obvious this shortcoming is; the current operating frequency range of existing products is 26GHz-40GHz, which cannot meet the development requirements of 50GHz spectrum analyzers

[0009] Agilent's SBTX product adopts a single balanced frequency mixing circuit, the low frequency band adopts the second harmonic mixing, and the high frequency band adopts the fourth harmonic mixing. The high frequency conversion loss is relatively large, which affects the sensitivity of the whole machine. Large difference in frequency conversion loss leads to poor frequency response in the entire frequency band

The use of barium-based hexagonal ferrite requires precise orientation of the resonator. This technology relies on foreign advanced technology and is difficult to realize.

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