L band Up Converter Suggestions

[srlraghuls]

Hi ,

I want to Convert 70Mhz IF signal to 950-1700MHz RF Signal in single stage. For Conversion The LO frequency selected can be 880-1630MHz or 1020-1770 MHz. But both the LO Frequency comes in the RF Pass Band. Suggest any way or Method to eliminate the LO Image Rejection.

 

[jiripolivka]

Tuning the LO calls for a tunable filter which is difficult. The best way then is to use the double conversion, with the second IF around 400--500 MHz.
An easier way is to choose two or three (etc.) LO frequencies for which you can design good filters, to reject the LO leak and image, too.
Another option is to upconvert first to say 5-6 GHz band, then use a variable LO to get to the desired band.

 

[AP31]

A dual conversion is the safe approach. However, you should create a frequency plan so that you can determine other unwanted frequency terms such as image and Harmonics of the LO. I'm assuming that the 950-1700MHz band is broken up into at least 2 separate bands (950-1325MHz) and (1325 - 1700MHz)? I some applications it may be worth while implementing both Hi and low side LO injection. However, in general hi side injections results in less fewer spurious or they are out of the band interest.