# How convert the differencial output to single end

1. ## How convert the differencial output to single end

I want to use a network analyzer to measure my chip. The network analyzer has a single end input, but the chip has a differencial output. I want to know how to convert the differencial output signal to a single input signal. Do I need some devices? What are they?Thank you very much!

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2. ## Re: How convert the differencial output to single end

differential output can simply b converted into single ended output by putting active load at the differential output.

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use balun?

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4. ## Re: How convert the differencial output to single end

use balun?
Basically yes, but it's suitability depends very much on the intended frequency range and measurement accuracy. Furthermore, a differential port has more network parameters than a single ended one, if you also consider common mode properties. If you have an ideal balun (actually it doesn't exist of course), common mode parameters would be ignored, with a real balun, it's limited symmetry and unknown common mode parameters of the differential port can cause large errors.

Another solution is to treat the differential port as two single ended ports and calculate all parameters from a two-port measurement. It works well in principle, but the accuracy may be possibly worse than with a balun measurement.

5. ## Re: How convert the differencial output to single end

Originally Posted by FvM
use balun?
Basically yes, but it's suitability depends very much on the intended frequency range and measurement accuracy. Furthermore, a differential port has more network parameters than a single ended one, if you also consider common mode properties. If you have an ideal balun (actually it doesn't exist of course), common mode parameters would be ignored, with a real balun, it's limited symmetry and unknown common mode parameters of the differential port can cause large errors.

Another solution is to treat the differential port as two single ended ports and calculate all parameters from a two-port measurement. It works well in principle, but the accuracy may be possibly worse than with a balun measurement.
Thanks! I want to use a balun to do that. However, the chip works in the IF part of the system and the work frequency range is 100k~2MHz. I don't know how to select a suitable balun. I want to use the products of Mini Circuit, but there are to many models. Could anybody introduce any experiece? Thank you very much!

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6. ## Re: How convert the differencial output to single end

oh, my god! Nobody, nobody! Is the question too easy to catch your eyes? Oh, come on! Nobody,nobody but you! Please help me!

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