Three working states of transistors and their characteristics
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Three working states of transistors and their characteristics

Posted Date: 2024-02-03

Three working states of transistors and their characteristics

A transistor is a semiconductor device that is often used in electronic circuits to implement functions such as amplifiers and switches. Transistors have three basic working states, including cut-off state, saturation state and amplification state.

The cut-off state means that the transistor is in the cut-off state when both the input voltage and the output voltage of the transistor are low level. In the off state, the control pin of the transistor (i.e., base or gate) is at a low level, causing the path between the collector or drain of the transistor to be broken. This means that in the off-state, the transistor conducts no current and cannot provide amplification. Furthermore, in the off state, the input resistance of the transistor is very high, close to infinity, and the output resistance is very low, close to zero. Therefore, the transistor in the off state does not consume a lot of power.

The saturation state means that the transistor is in a saturated state when both the input voltage and the output voltage of the transistor are high. In saturation, the transistor's control pin (i.e., base or gate) is high, causing a path to form between the transistor's collector or drain. This means that in the saturated state, the transistor is able to conduct current and has a low resistance. Furthermore, a transistor can provide maximum amplification in its saturated state, as this is when the maximum current flows through the transistor and the maximum voltage across the transistor. Therefore, a transistor in a saturated state can effectively amplify electrical signals.

The amplification state means that when the input voltage of the transistor is low level and the output voltage is high level, the transistor is in the amplification state. In the amplified state, the transistor's control pin (i.e., base or gate) is at a low level, causing the transistor's collector or drain to form a path. Unlike the transistor in the saturated state, the transistor in the amplified state does not completely put the current into the path, but uses the current from the control pin to regulate it. This means that the transistor in the amplified state can amplify the signal according to the size and type of input voltage. The amplification factor of a transistor in the amplified state depends on its operating current and transfer characteristics.

To sum up, the three working states of the transistor have the following characteristics:

1. The transistor in the off state does not conduct current and has low power consumption.

2. The transistor in the saturated state can conduct current, has low output resistance, and can provide maximum amplification function.

3. The transistor in the amplified state is adjusted by the current of the control pin, and can amplify the signal according to the size and type of the input voltage.

These three working states are widely used in electronic circuits, and the working states of the transistors can also be switched as needed to achieve different functional applications. Therefore, a deep understanding of the three operating states of transistors is important for designing and understanding electronic circuits and other applications.


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