Development On The Miniaturization Of 4300M/80M Up&down Frequency Converter Module

The issue develops the up and down frequency converter module for the transmitting and receiving channel of the miniaturization portable responder. The transmitting channel requires to convert the 80±10M base signal to 4.3G±10M which will be transmitted by antenna, and realizes the output power changeable from-80 to +10dbm. The receiving channel requires to convert 4.3G±10M pulse signal to base signal which power is up to 40 to 60 dBm, and uses the programmable amplifier to change the gain of the amplifier to keep the output power to 0±3dBm. The base signal will be sent to the modulation and demodulation module to be processed.According to indexes put forward in this paper, the adjacent channel ratio is larger than 50 dB. This paper take the way of using filter on IF band to process the adjacent channel ratio. It solves the problem of the high cost and large volume and hard to develop of the filter of the filter on 4.3G, and also solves the contradiction between high adjacent channel ratio and low cost and miniaturization of the filter on 4.3G. To confirm the design scheme is reliable, the writer uses microwave office to simulate the up and down converter system. This article involves various components and multiple modules: high power direction coupler, 80M±10MHz band pass filter, 4300M±20M band pass filter, a microstrip low-pass filter, power splitters applied to the band 80M±10M designed by passive components, and test the independent component high power direction coupler and the filters. The test improves that the input VSWR of the high power direction coupler is a little higher than required, the output VSWR is very well, and the degree of coupling is flat. The characteristics of margin and frequency of the filter is sharp. Use the chip ADF4350 to design a frequency synthesis to produce a local oscillator signal,and use KeilC51 to program the MCU and control the output of the frequency synthesis, attenuation of the attenuator, gain of amplifier. Then use SolidWorks to draw the shell of the module, and mark size by AutoCAD. Finally, test the up frequency converter chain, the results match the indexes.