Analyzing a Current Mirror: Finding Rref for Vcc=8V and Icopy=0.38mA

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SUMMARY

This discussion focuses on calculating the reference resistor (Rref) for a current mirror circuit with a supply voltage (Vcc) of 8V and a copy current (Icopy) of 0.38mA. Participants clarify that while the base current (IB) is not explicitly stated, it can be assumed negligible due to the high beta of the transistor, allowing for simplification in calculations. The consensus is that the base current is not zero but can be ignored for practical purposes in this scenario.

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Homework Statement


I am working on this problem. They start out by giving me:
upload_2017-9-25_20-44-28.png

I am asked to find Rref such that Vcc=8V and Icopy=0.38mA.

Homework Equations


Transistor equations

The Attempt at a Solution


In this case, they never specify if IB=0A (sometimes it does ?) but I would assume that it is and therefore beta would be very large and we ignore this.

upload_2017-9-25_20-51-11.png
 
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That's the answer I got.
 
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Cocoleia said:
In this case, they never specify if IB=0A (sometimes it does ?) but I would assume that it is and therefore beta would be very large and we ignore this.

Right answer but you have the explanation backwards...

Beta is high so the base current is much smaller than the collector current. Therefore the base current can be ignored (but the base current isn't zero).
 
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