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Can a downconversion mixer be used as an upconversion mixer?

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smash85

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Just a basic theorical question:

Can a downconversion mixer be used as an upconversion mixer by just switching the input/output ports ? (assuming the frequency ranges of all the ports are respected)

i.e. RF = 2-20 GHz, LO = 2-20GHz, IF = 0-2 GHz

Downconversion i.e. RF = 20 GHz, LO = 19 GHz, then output IF = 1GHz

then use the same mixer for upconversion:

i.e. LO = 10 GHz, IF = 2 GHz, and output RF = 12 GHz

thanks
 

Yes it can be used. Mixers downconvert and upconvert at the same time. Whichever you want at the output you filter out the other by using a filter accordingly. So it actually upconverts too...
 

Re: Can a downconversion mixer be used as an upconversion mi

If you are going to up convert, put the lower frequency signal to the IF port and take the higher frequency from the RF port. Make sure that the mixer has the proper frequency range for all three port signals.
 

i advice u to read the datasheet , coz some mixers include filters in the ports so it wont work.

but in gernral theory they can , so u need to invest sometime making sure that this mixer will work in both cases

khouly
 

Re: Can a downconversion mixer be used as an upconversion mi

Thanks for the help,

Another question:

Can an Image Rejection Mixer also be used as an Single Sideband Upconverter if there are no filters and the frequency ranges are right ?

Also, if I have a situation like this:

I want to downconvert a signal from RF = 20 GHz to IF = 1 GHz. The LO is supposed to be at 21 GHz. I am certain that the only signal coming from the RF port is 20 GHz, but the LO signal might also be present at 19 GHz. Is this a problem as both with downconvert to 1 GHz ?
 

Re: Can a downconversion mixer be used as an upconversion mi

smash85 said:
Thanks for the help,

Another question:

Can an Image Rejection Mixer also be used as an Single Sideband Upconverter if there are no filters and the frequency ranges are right ?

Also, if I have a situation like this:

I want to downconvert a signal from RF = 20 GHz to IF = 1 GHz. The LO is supposed to be at 21 GHz. I am certain that the only signal coming from the RF port is 20 GHz, but the LO signal might also be present at 19 GHz. Is this a problem as both with downconvert to 1 GHz ?
Click to expand...

How the LO signal can have two components at 19GHz and 21GHz simultaneously ?? Inversily, the RF signal can have 20GHz and 22GHz component thatwill be as"Image frequency"..In this case both down conversion components will be appeared at 1GHz. This is the problem...

Second thing..
If you use Gilbert Cell style mixer, you can not inverse the LO port and RF port becaue LO ports are connected to the bases of the transistors to maintain the switching function, and RF ports are connected to the bases of the differential pairs to maintain the amplifying function.Therefore these ports are not interchangable.

Otherwise, for diode mixers, RF an LO ports are generally interchangable...
 

Re: Can a downconversion mixer be used as an upconversion mi

Here is how:

The fixed IF oscillator is mixed with the transmit RF to give the receive LO which might have freqs RF+IF or RF-IF. The received signal is only RF.

This is why I want to know if I should be concerned on eliminating the unwanted sideband while upconverting.
 

Re: Can a downconversion mixer be used as an upconversion mi

didnt get an answer yet, bringing this post back up
 

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