# Circuit Analysis with VCCS and VCVS

• Engineering

## Homework Statement

For the circuit in Figure P1.42, suppose R3 = 2*R2, and R2 = 10 * R1. Find the resistor values so that Gv = Vout/Vin = 1000. ## Homework Equations

V = IR

for Voltage Controlled Current Source - i(t) = gm * vx
for Voltage Controlled Voltage Source - v(t) = μ * vx

## The Attempt at a Solution

Everytime I try to figure out the resistor values I get R3 = 500. The answer is R3 = 5 k ohms which the book gives us.

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lewando
Homework Helper
Gold Member
Unless I'm losing my mind, it looks like Vout = 5V2, which is independant of the value of R3.

Unless I'm losing my mind, it looks like Vout = 5V2, which is independant of the value of R3.

I said that
Vin = Iin*R1

V2 = .8*Vin * R2
= .8 (Iin*R1) * R2

Vout = 5*V2
= 5 * (.8 (Iin*R1) * R2)

CWatters
Homework Helper
Gold Member
I think R3 is only needed to calculate Iout not Vout.

Rest deleted as I made a mistake.

lewando
Homework Helper
Gold Member
Those look fine. If you combine

V2 = .8*Vin * R2

and

Vout = 5*V2

you can get an expression for Vout/Vin as a function of R2 only.

Using your stated constraint for R3 = 2R2, I also come up with R3 = 500 ohms.

Those look fine. If you combine

V2 = .8*Vin * R2

and

Vout = 5*V2

you can get an expression for Vout/Vin as a function of R2 only.

Using your stated constraint for R3 = 2R2, I also come up with R3 = 500 ohms.
Is it possible that we are a factor of ten off?

lewando
Homework Helper
Gold Member
I think it is more likely that your book is off by a factor of 10. Are you sure that R3 = 2*R2? Maybe an additional set of eyes on this problem might build the case against your book.

I think it is more likely that your book is off by a factor of 10. Are you sure that R3 = 2*R2? Maybe an additional set of eyes on this problem might build the case against your book.
This is the question from the book: As it turns out, the book was off. It was supposed to say .5 k Ω and not 5.

lewando
Homework Helper
Gold Member
That's great! Thanks for the closure.