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Measurement of Voh spec for receiver with CMO (Read 2783 times)

dandelion

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Measurement of Voh spec for receiver with CMO
Nov 01^st, 2006, 11:13pm

Hi,
In many receiver(CMOS/TTL level output)product, it gives the spec of the output high voltage(Voh) as below;
.........
Voh 3.8V-typ 4.9V-max

the test condition above is Ioh=2mA,Vid=+200mv
...........
I drafted the testbench for the above as attached diagram.

I want to know if the current source in th ediagram is used in the test. Someone told me it is replaced by the resistor.

And also, if I want to deisgn a receiver chip, in the design, how can I simulate this spec?Used an ideal current source?

Thanks

voh_test.jpg

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topquark

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Thames Valley, UK

Re: Measurement of Voh spec for receiver wit
Reply #1 - Dec 7^th, 2006, 4:21am

Hi,
Hope you may have resolved this.
Anyway, just trying to see if my understanding's correct:
Voh is the min. o/p level that's read as a logic "high" and Ioh is the current flowing into (a specified) o/p load under that condition, usually it's a capacitive load in case of CMOS.
As for your testbench, i/p conditions are ok but at the o/p you need to just put a variable o/p cap load & simulate.
measure Vout when Iout is 2mA. This will be your Voh.

Hope this's the way you did it.

Regards,
Gautham

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