This ensures that the transistor is never turned on fully, which would cause it to draw too much current and possibly overheat. It does this by dividing the voltage between the collector and emitter of the transistor into two equal parts. Why Is Voltage Divider Bias Used?Ī voltage divider bias is used to create a stable quiescent operating point for a transistor amplifier. As voltage falls at the resistor R2, the junction of the base-emitter and the resistor is required to operate in forward bias.Īn amplifier biaser is a device that detects whether a device is active and sets the initial operating conditions (current and voltage). The resistor in this circuit is good for providing stabilization, which is why it is referred to as voltage-diversification. The base current and collector current flow are both affected because they are affected by the zero signal condition. The voltage drop in R2 forward causes the base-emitter junction to shift. Voltage Divider Bias Method for a Voltage Divider This name comes from the fact that the voltage dividers R1 and R2 are identical. To ensure that voltage is divided and distributed evenly into the transistor, a few resistor are used. A voltage divider bias is an obvious and most commonly used technique to bias a transistor. Using biasing pairs adds an important level of freedom to the design.Īn voltage divider bias method can be used to bias a BJT transistor. In general, better thermal control and quiescent current stability can be obtained with greater voltage variations allowed across %R_E%$.

Negative feedback can sometimes be used to correct open loop gain variations caused by other factors. In a wide variety of applications, a emitter resistor can be used to set the quiescent current. The only costs are the components (and operating power). Moreover, voltage divider bias also reduces the effects of temperature variation on the transistor’s operating point.Īs a result, biasing is a more convenient method of using a resistor at the base than a single pair at the top.

In other words, it ensures that the transistor remains in active region and does not enter into saturation or cutoff. The main reason for using voltage divider bias is that it provides a stable quiescent operating point for the transistor. Voltage divider bias is a popular biasing technique used in amplifiers.

Importance of transistor biasing