Help! Intend to use mini-circuit mixer IF as input, Rf as output!

Hello,
I notice there once was a similar post on this topic. Based on the suggestion in that post, it seems to be Okay to use mixer 'IF' as input, 'Rf' as Output.

However, I reviewed the simplified schematic of the selected mixer. Still a bit of concern on this usage. You could see in attachment, that mixer's schematic indicates different transformer schema on IF and RF port. I wonder if that would affect this usage. Or, the selected mixer won't cause any problem at all. Expecting your reply!

Thanks advance!

Jeff

Yes, what you are talking about is standard practice. For an upconverter, the IF is input and RF is output. For a downconverter the RF is input and IF is output.

The mixer you posted is a triple-balanced diode mixer (using baluns at all 3 ports), and on this type of mixer I think you cannot swap RF and IF ports and getting the same performance as in double-balanced case, due to circuit involved.

vfone said:

The mixer you posted is a triple-balanced diode mixer (using baluns at all 3 ports), and on this type of mixer I think you cannot swap RF and IF ports and getting the same performance as in double-balanced case, due to circuit involved.

Click to expand...

The OP is just talking about direction of the signal (whether RF could be input or output) which is OK. I believe what you are thinking of is that for triple balanced mixer the IF port will not extend to DC on the low end. For either double or triple balanced though, as long as you stay within the allowed RF and IF frequency ranges it can be used as upconverter or downconverter.

Yes, you can do it. Will the mixer performance be "optimized"? Maybe not.

Specifically, the port to port leakage and the spurious signal levels (M x N products) may be different if you drive the IF port with the high power instead of the LO port. Sometimes the only way to tell is to actually test a unit.

Similarly, for some applications, you may choose to drive the RF port with the high poiwer, and use the LO port as a low power input or output.

About the only mixers you can not do this with are newer "comutating types", where you are driving fet gates instead of diode quads.

Hi Biff44 and above,
Thanks for your information and comment on this.
The context forcing me to use the mixer as upconverter is higher IF frequency than RF input. So, I have to route the RF input signal into mixer's IF port, then up-convert to higher IF frequency. My current plan is to drive the LO level as datasheet specified, and control the level into mixer's IF port to something below -30dBm, which I believe won't cause too much inter-modulation. I did place SMA connector near Mixer's RF/IF port on my trial board. Before I sent the board to PCB factory, I just want to make sure what I did is reasonable, because, I'm really of little knowledge on this part.

Thanks again for all comment and helpful suggestion!

Jeff

biff44 said:

Yes, you can do it. Will the mixer performance be "optimized"? Maybe not.

Specifically, the port to port leakage and the spurious signal levels (M x N products) may be different if you drive the IF port with the high power instead of the LO port. Sometimes the only way to tell is to actually test a unit.

Similarly, for some applications, you may choose to drive the RF port with the high poiwer, and use the LO port as a low power input or output.

About the only mixers you can not do this with are newer "comutating types", where you are driving fet gates instead of diode quads.

Click to expand...

Before you make the pcb, please check the mixer IF and RF and LO frequency band. make sure you IF and higher IF and LO are in the range of the mixer from the datasheet. Out of range can cause many problems.