Biasing

To work efficiently, transistors or tubes require the right bias. This means that the control electrode-the gate, base, or grid-should have a certain voltage or current. Different bias levels are required for different types of circuits. A radio transmitting amplifier would be biased differently than an oscillator or a low level receiving amplifier. At times voltage division is required for biasing. Other times it is not essential, figure given below shows a transistor whose base is biased using a pair of resistors in the voltage-dividing configuration.

Figure--   Voltage divider for biasing the base of a transistor.