ANS:D - hold the circuit stable at the designed Q-point

Bias voltage typically refers to an electrical charge applied to the gate or base of a transistor or FET's. This applied voltage causes the component to become conductive, thereby passing electrical current through its collector and emitter stages.

The amount of current passed through the component is also directly related to the amount of bias voltage applied. Depending on the type of transistor, this voltage is either positive or negative and is referred to as a forward or reverse bias.

These voltages are, therefore, used to switch electronic components on or off, keep them active, or control the amount of current passing through them.