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number of the output transistors

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drabos

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What are the main reasons in the decision about the numbers of the transistors in an output stage?

So, using 10 MOSs or 20 MOSs or more...

Thanks,
 

A.Anand Srinivasan

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it is mainly the consideration on the output capacitance and the power sourcing capability...
 

    drabos

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pichuang

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A.. Anand Srinivasan is right. The more output transistors (we call it fan out devices), the more capacitance. I am not too sure about Analog IC, but in digital IC it is often a better practice to limit the number of fan out devices to be less than 4 whenever possible.
 

    drabos

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sohiltri

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For MOS transistor fanout of 50 is possible....It all depends on total load capacitance offered.....more the fanout slower the device....
But How power sourcing capability will affect Fanout in MOS?
 

    drabos

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A.Anand Srinivasan

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more MOS means the power supply should be capable of supplying a lot of power especially when the MOS undergoes transition....
 

    drabos

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ameed

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hi all,

The more output transistors (we call it fan out devices), that will effect on directly the more capacitance.

about Analog IC, but in digital IC it is often a better practice to limit the number of fan out devices

to be less than 4 whenever possible.

thanx....
 

    drabos

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