How to test a dual output mixer??

[yorande]

I am doing a mixer chip. But how to test the low IF output?
I choose 20MHz. It seems a bit too low for baluns.
How do people test direct conversion mixers? Seems seldom mentioned.
Thanks.

 

[haizal]

is the same time and the same question that i would ask for anybody can help me..
i'm designing for my final year project using microstrip fr-4 for designing direct conversion receiver and usage of mixer using hybrid coupler as part of RF.

 

[gecky]

Hi,

If baluns don't work, try using RF transformers. Check out minincircuits.com . This is supposing that you can interface your chip to HMIC.

When you say low IF, you mean the downconverted signal right? As in IF_lo = RF - LO ?

 

[yorande]

Yes, I mean downconverted signal..
I get it down to 20MHz from 430MHz. and when I ask a microwave engineer whom I know during my intership he said that the frequency is too low.
I would check out transformers then. Have not yet get materials about them.
Still busy in the layout work.
Could transformers be easily design and realized by devices?
Thanks.

 

[gecky]

Hi,

you'll be better off getting commercial transformers. Less you want to spend time coiling wire on ferrite cores. Besides, minicircuit ones are pretty broadband in the range you are working.... problem is the attenuation... Another mnf you can check out is coilcraft.

I'm unsure what sort of equipment you plan to use for measurement.... most likely a spectrum analyser, in which case 20MHz is no problem... you can even view the waveform on the good old CRO

Try not to use the xformer if it is uneccessary, it's passband is not flat and will distort your measurement.... less u do some characterisation befoehand.


Good Luck!