Why is a bias resistor added to a transistor? 2

Why do transistors need bias resistors?

The transistors itself is a nonlinear component, and its operating point is uncertain without a bias resistor. This means that the operating point of the transistor may change under different temperature, power supply voltage, and other conditions, which may lead to circuit instability or abnormal operation.

By adding bias resistors, the operating point of the transistors can be relatively stable, improving the reliability and stability of the circuit. The bias resistor can be selected according to the parameters and operating requirements of the transistor to ensure its normal operation.

In addition, bias resistors can also help adjust the current amplification factor of the transistors, thereby improving the linearity of the circuit. Linearity is crucial for both amplifier circuits and switch circuits, as it determines the precise relationship between input and output signals.

In short, bias resistors play a crucial role in transistors circuits, as they can stabilize the operating point of the transistor, improve the reliability, stability, and linearity of the circuit.