Voltage at the output/Parallel resistors

In summary, the conversation discusses the output voltage, Vo, and how it is taken directly in parallel with Ro. It is mentioned that the output voltage should be equal to the voltage across the three parallel resistor components, but the reason for combining these resistors into RL' is not clear. It is suggested that the total current passing through all three resistors is known, making it possible to solve the circuit in different ways.
  • #1
dalarev
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0

Homework Statement



Reading the voltage taken at the output, Vo.

Homework Equations



Resistors in parallel carry the same voltage.

The Attempt at a Solution



The circuit shown in the diagram, the output is taken directly in parallel with Ro, so shouldn't that mean that:

VRL = VRD = Vro ?

In calculating the output, they combine all those 3 resistors in parallel into RL', I don't understand why.


In other words, why doesn't Vo = VRL ?
 

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  • #2
The output voltage is indeed the voltage across those three parallel resistor components. It doesn't matter if they are drawn as 3 resistors or the equivalent single resistor, unless some individual current is needed for some other part of the model calculation.
 
  • #3
I might be repeating the above post:

The circuit shown in the diagram, the output is taken directly in parallel with Ro, so shouldn't that mean that:

VRL = VRD = Vro ?
Yes

In calculating the output, they combine all those 3 resistors in parallel into RL', I don't understand why.
You don't know the voltage across either of those three. But the total current passing through all three resistors is g_m*V_gs which is known as I am assuming. You can go solve the circuit in either way: it's a simple circuit with three resistors in parallel and one current source. Simplest possible method is to combine all three ll resistors and find the voltage.
 

1. What is voltage at the output?

Voltage at the output refers to the electrical potential difference between the output terminal of a circuit and the reference point, typically ground. It is measured in volts (V) and represents the amount of energy available to drive an electric current through a circuit.

2. How is voltage at the output calculated?

Voltage at the output can be calculated using Ohm's Law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). In a parallel circuit, the total resistance is equal to the reciprocal of the sum of the individual resistances: 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ... Therefore, the voltage at the output can be calculated by dividing the total current by the total resistance.

3. What is the relationship between voltage at the output and parallel resistors?

In a parallel circuit, the voltage at the output remains the same across all branches of the circuit. This means that each parallel resistor will have the same voltage drop as the output voltage. However, the current flowing through each resistor may vary depending on their individual resistances.

4. How does the number of parallel resistors affect the voltage at the output?

The more parallel resistors there are in a circuit, the lower the overall resistance and the higher the current. This means that the voltage at the output may decrease if the total resistance decreases, and vice versa. However, the voltage at the output will still be the same as the voltage across each parallel resistor.

5. Can the voltage at the output be higher than the input voltage in a parallel circuit?

No, the voltage at the output in a parallel circuit cannot be higher than the input voltage. This is because the voltage drop across each parallel resistor is the same as the output voltage, and the sum of these voltage drops cannot exceed the input voltage. However, the overall current in a parallel circuit may be higher than the input current due to the lower total resistance.

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