| In the field of radio communication,navigation,identification and radar system,microwave and millimeter have been widely used for their unique transmission properties.The up conversion circuits convert low frequency signal to higher frequency,and they have played an important role in radio transmitters.The down conversion circuits convert high frequency signal to lower frequency,and they are also important in radio receivers.There are many difficulties in the design of frequency conversion circuits,and the demand continues to improve.Also the technology is developing quickly both at home and abroad.The content of this thesis is about a design of frequency conversion module based on an advanced research.The module converts Ku-band signal to intermediate frequency(IF),and IF signal to L-band.The module owns three serial communication interfaces.It has also brought about the control of working frequency and output power.According to the requirements,the thesis has analyzed the performance index of radio receivers,and chosen the super heterodyne structure.Based on the theory of phase-locked loop(PLL),the scheme of Ku-band down converter and L-band up converter has been determined.In the Ku-band down conversion circuit,the input RF signal(12250MHz-12750MHz)is converted to 140 MHz and output after down conversion twice,filtering,amplifying and AGC.In L-band up conversion circuit,the input IF signal is converted to RF(950MHz-1450MHz)after band-width control,up conversion twice,filtering,amplifying and power control.The control circuit with FPGA and some other chips has accomplished three serial interfaces,the control of two PLLs and the control of output power.The module was tested,and the Ku-band down conversion,the L-band up conversion and the serial communication have all met the requirements.The module can also work normally in high temperature,low temperature and vibration tests.The module has fully met the requirements of the project and has good prospect for development. |
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