This is shown by the portion of the characteristic curve between points B and C in Figure (b). This results in fewer holes for recombination in the base region which effectively causes a slight increase in βDC. Actually, IC increases very slightly as VCE increases due to widening of the base-collector depletion region. Once the base-collector junction is reverse-biased, IC levels off and remains essentially constant for a given value of IB as VCE continues to increase. Ideally, when VCE exceeds 0.7 V, the base-collector junction becomes reverse-biased and the transistor goes into the active, or linear, region of its operation. IC increases as VCC is increased because VCE remains less than 0.7 V due to the forward-biased base-collector junction. This is indicated by the portion of the characteristic curve between points A and B in Figure (b). Saturation is the state of a BJT in which the collector current has reached a maximum and is independent of the base current.Īs VCC is increased, VCE increases as the collector current increases. When both junctions are forward-biased, the transistor is in the saturation region of its operation. The base current is through the base-emitter junction because of the low impedance path to ground and, therefore, IC is zero. For this condition, both the base-emitter junction and the base-collector junction are forward-biased because the base is at approximately 0.7 V while the emitter and the collector are at 0 V. Notice in the circuit diagram that both VBB and VCC are variable sources of voltage.Īssume that VBB is set to produce a certain value of IB and VCC is zero.
![collector current vs vce pc1d collector current vs vce pc1d](https://cdn.dribbble.com/users/1728242/screenshots/15134793/media/40c4e87823df3621d42cc701428dcd51.jpg)
Using a circuit like that shown in Figure (a), a set of collector characteristic curves can be generated that show how the collector current, IC, varies with the collector-to-emitter voltage, VCE, for specified values of base current, IB.