I have a few questions about Vce(sat) and static resistance

In summary: The static resistance in semiconductors will decrease if the semiconductor is more heavily doped. This resistance is what causes the voltage drop between the emitter and the collector, which is known as Vce(sat).
  • #1
Genji Shimada
46
4
I think this is the place to ask these questions about static resistance of semiconductors:
The static resistance in semiconductors is that kind of resistance that will decrease if the semiconductor is more heavily doped, right?

In transistors, and especialy saturated transistors the usual 0,2V voltage drop between the emitter and the collector is the inevitable loss of energy duo to the static resistance of the semiconductor. Is that right?

If so, that voltage drop will slightly increase with the increase of the collector current, right?
 
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  • #3
anorlunda said:
Ah! And so because of this resistance, the transistor will drop some voltage between the emitter and the collector even though it is expected to act like a short circuit when saturated. My point is that it is that sheet resistance that causes that Vce(sat) right?
 
  • #4
This minimum voltage drop is not due to the resistance but to the need to forward polarize one of the junctions.
I don't understand though where do you get the 0.2 V. For silicon transistors (junction type) is about 0.7 V.
Maybe you are talking about a different type of transistor? What kind of transistor do you mean?
 
  • #6
nasu said:
This minimum voltage drop is not due to the resistance but to the need to forward polarize one of the junctions.
I don't understand though where do you get the 0.2 V. For silicon transistors (junction type) is about 0.7 V.
Maybe you are talking about a different type of transistor? What kind of transistor do you mean?
I don't speak about the minimum turn on voltage you need to apply across a diode in a forward dirrection to turn it on. I am talking about the voltage difference between the emitter and the collector when a transistor is saturated:
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FAQ: I have a few questions about Vce(sat) and static resistance

What is Vce(sat)?

Vce(sat) stands for the saturation voltage of a transistor. It is the minimum voltage that needs to be applied between the collector and emitter terminals of a transistor to maintain a desired level of collector current.

How is Vce(sat) measured?

Vce(sat) can be measured by applying a specific base current to the transistor and gradually increasing the collector-emitter voltage until the desired level of collector current is reached. The voltage at this point is the Vce(sat) value.

What factors affect Vce(sat)?

There are several factors that can affect the Vce(sat) value, including temperature, collector current, and the characteristics of the transistor itself. Generally, higher temperatures and higher collector currents can result in higher Vce(sat) values.

What is the difference between Vce(sat) and static resistance?

Vce(sat) and static resistance are two different parameters used to describe the behavior of a transistor. Vce(sat) is a voltage measurement, while static resistance is a measure of the relationship between the collector current and the collector-emitter voltage. Vce(sat) is typically used to determine the operating point of a transistor, while static resistance is used to analyze the linear region of the transistor.

Why is Vce(sat) important?

Vce(sat) is an important parameter in the design and analysis of transistor circuits. It helps determine the maximum collector-emitter voltage that can be safely applied to the transistor, as well as the power dissipation and efficiency of the circuit. Understanding Vce(sat) also allows for proper biasing and selection of transistors for specific applications.

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