Why input resistance of a transistor is low?
While using a transistor, the emitter-base junction is always forward biased and the collector-base junction is always reverse-biased. Due to it, a small change in emitter current. This means that a small signal voltage variation at the input of the transistor produces a large emitter current variation. This showed that the input resistance of a transistor is low.
Since the collector is reverse-biased, it collects all the charge carriers which diffuse into it, through the base. Due to it, a very large change in collector voltage shows only a small change in the collector current. This shows that the output resistance of the transistor is high.
How to Calculate Small-Signal Input Resistance between Base and Emitter?
Small-Signal Input Resistance between Base and Emitter calculator uses Signal Resistance = Input Voltage/Base Current to calculate the Signal Resistance, The Small-signal input resistance between base and emitter suggests that for a small signal, the transistor behaves as a voltage-controlled current source. The input port of the controlled current source is between base and emitter and the output port is in between collector and emitter. Signal Resistance is denoted by Rs symbol.
How to calculate Small-Signal Input Resistance between Base and Emitter using this online calculator? To use this online calculator for Small-Signal Input Resistance between Base and Emitter, enter Input Voltage (Vin) & Base Current (IB) and hit the calculate button. Here is how the Small-Signal Input Resistance between Base and Emitter calculation can be explained with given input values -> 0.032468 = 2.5/7.7E-05.