# Analog electronics (BJT circuit analysis)

• Engineering

## Homework Statement For beta = 100 and assuming ro is very large, what is the DC voltage at the collector?

IB = IE(β+1)

IC = β*IB

## The Attempt at a Solution

Since IE = 0.5mA, IB = 0.0505 A
Then, IC = 5.05 A (which doesn't feel right)
VC is the same potential across the 30kΩ load?
I tried doing KCL with those currents (to find the current thought the load resistor).
Should I not be analyzing the direct circuit--should I make an equivalent T-model?

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## Homework Statement

View attachment 110203
For beta = 100 and assuming ro is very large, what is the DC voltage at the collector?

IB = IE(β+1)

IC = β*IB

## The Attempt at a Solution

Since IE = 0.5mA, IB = 0.0505 A
Then, IC = 5.05 A (which doesn't feel right)
VC is the same potential across the 30kΩ load?
I tried doing KCL with those currents (to find the current thought the load resistor).
Should I not be analyzing the direct circuit--should I make an equivalent T-model?
Your equation should read ## I_E=I_B (\beta+1) ##. Try again. I think you also need to assume ## V_{BE}=.7 \, volts ## (approximately). One hint for you: The capacitors basically block any steady state current trying to go through them so the capacitor is an open circuit for the DC part of the analysis.

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