Bipolar transistor amplifiers have to be properly biased to operate properly. In circuits made up with individual devices (discrete circuits), biasing networks containing resistors are commonly employed. More elaborate biasing arrangements are employed in integrated circuits, for instance, current mirrors and band gap voltage references.
The device's operating point, also termed bias point, quiescent point, or Q-point, is the point on the output characteristics which depicts the DC collector-emitter voltage (Vce) and the collector current (Ic) without input signal applied. The word is generally employed in connection with devices like transistors.