# Homework Help: Large signal dc analysis for bjt circuit (problem)

1. Jun 11, 2012

### Klypso

1. The problem statement, all variables and given/known data
Consider the circuit shown below. A Q-point value for IC between a minimum of 4 mA
and a maximum of 5 mA is required. Assume constant resistor values, and suppose
that b ranges from 100 to 300. It is desired that RB have the largest possible value
while meeting the other constraints. Find the values of RB and RE. The resistors in
this problem are not required to be nominal values.

2. Circuit
Since i can't post the link for the circuit, you can search for " largest possible value
while meeting " in google and go to the first link (Electronics Homework Set #8) the circuit is the first one.

3. The attempt at a solution
15=1000*i_c+R_e*i_e+V_ce
5=R_b*i_b+0.7+R_e*i_e

Thank you.

2. Jun 12, 2012

### Staff: Mentor

Hi Klyso, Welcome to Physics Forums.

Can you provide more of an attempt at solution? It's not clear from what you've written what your idea is for approaching the problem.

Hints: Can you identify the currents that will flow through the emitter? Do you know values for any of them (or at least ranges of values?) How do they depend upon each other (what is the influence of β)?

Here's the circuit diagram that you couldn't post, for others to view:

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