# Amplifier design level shifting stage w/ current source equations

#### wazzizit

Joined Jan 14, 2015
19
Could anyone help by giving the equations used to calculate the resistor values in the circuit attached please?

Many Thanks

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#### Jony130

Joined Feb 17, 2009
5,243
All transistor in your diagram are connected backward or simply you are using wrong transistor type.

#### wazzizit

Joined Jan 14, 2015
19
The top and bottom power supplies are the wrong way round. Assuming they're flipped, how do I derive the res values please?

#### Jony130

Joined Feb 17, 2009
5,243
Well all you need is Ohm's law and two Kirchhoff's laws.
Ic2 = Ic1 = Ic3 = (Vd - Vbe1)/R1
And
Vo = Vi + Vbe3 +Ic3*R3

#### wazzizit

Joined Jan 14, 2015
19
Any chance you could sub in some values please? I'm struggling to know what the Vbe, Ic2, Ic1 and Ic3 values are

#### Jony130

Joined Feb 17, 2009
5,243
You do not know what Vbe is ??

#### wazzizit

Joined Jan 14, 2015
19
I know it's the voltage from base to emitter...

#### Jony130

Joined Feb 17, 2009
5,243
And typical Vbe values is ??

#### wazzizit

Joined Jan 14, 2015
19
.7V?

#### Jony130

Joined Feb 17, 2009
5,243
Yes.

#### wazzizit

Joined Jan 14, 2015
19

#### crutschow

Joined Mar 14, 2008
27,711
You need to take a stab at it before we can help.

The is Homework Help forum, not a Do Your Homework one.