Why is a bias resistor added to a transistor? 1

The bias resistor is an important component used in transistor circuits to stabilize the operating point of the transistor and ensure its normal operation.

A  transistor is an electronic device commonly used in amplifier circuits and switch circuits. In order for the ATMEGA2560-16AU transistor to function properly, it is necessary to bias it, providing it with a suitable operating point to enable it to function properly in the amplifying or switching state. The bias resistor is used to achieve this purpose.

Specifically, the functions of bias resistors include the following aspects:

1. Determining the operating point: The bias resistor determines the operating point of the  transistor by controlling the magnitude of the base current and emitter current, that is, the current and voltage values in the DC operating state. The choice of operating point is crucial for the amplification or switching characteristics of the transistor.