Can a transistor act as switch and amplifier?
When a transistor works in an active region the transistor acts as an Amplifier and when it works as a Switch it works in Cutoff and Saturation Regions. Transistor switches can be used to control lamps and switches, relays or even motors.
What is the difference between a transistor being used as a switch and as an amplifier?
As a switch the transistor is operating as a resistance (Ron) when it is on and an open when the switch is off. When the transistor is operating as an amplifier, the device is operating as a transconductor, a VCCS (voltage controlled current source).
What is a transistor switch?
Transistor switches can be used to switch a low voltage DC device (e.g. LED’s) ON or OFF by using a transistor in its saturated or cut-off state When used as an AC signal amplifier, the transistors Base biasing voltage is applied in such a way that it always operates within its “active” region, that is the linear part of the output
What is the biasing of a transistor?
If the circuit uses the Bipolar Transistor as a Switch, then the biasing of the transistor, either NPN or PNP is arranged to operate the transistor at both sides of the “ I-V ” characteristics curves we have seen previously. The areas of operation for a transistor switch are known as the Saturation Region and the Cut-off Region.
Why do we use multiple switching transistors in bipolar transistors?
Sometimes the DC current gain of the bipolar transistor is too low to directly switch the load current or voltage, so multiple switching transistors are used. Here, one small input transistor is used to switch “ON” or “OFF” a much larger current handling output transistor.
What is the output voltage of a Si-transistor?
In the case of a Si-transistor, we note that as long as the input voltage is less than 0.6 V, the transistor remains in the cut off state and the current I is zero, and hence we can write, is greater than 0.6 V the transistor remains in its active state and the current I c is obtained in the output path.