A Si diode (p-n junction) is connected to a resistor R and a biasing battery of variable voltage VB. Assume that diode requires a maximum current of 1 mA to be above the knee point (0.7 V) of its V-i characteristic curve. Also assume that the voltage V across the diode is independent of current above the knee point. If VB = 5 V, what should be the maximum value of R so that the voltage V is above the knee-point voltage?
Let VR and V be the voltages across the resistor R and the diode respectively. Then
For R to be maximum (Rmax), the current i should be minimum . Thus, by Ohm’s law
In a pn junction dipole at a high value of reverse bias, the current rises sharply. The value of reverse bias is known as
The total current in the block is
In a pnp transistor, the p-type crystal acts as
The current gain in a common emitter transistor is
If the input and output resistances in a common-base amplifier circuit are respectively, what is the voltage amplification when the emitter current is 2 mA and current gain ?
When npn transistor is used as an amplifier
When a pn junction is reverse biased, the flow of current across the junction is mainly due to
The V-i characteristic of a silicon diode is given in the figure. Calculate the diode resistance in forward bias at V = +2 volt.
A forward-biased p-n junction diode has a potential drop of 0.5 V which is assumed to be independent of current. The current in excess of 10 mA through the diode produces so much heating that burns the diode. If we have a 1.5 V battery to bias the diode, resistor must be used in series with the diode so that the maximum current does not exceed 5 mA?
In the circuit (a), calculate the current in the resistance. Assume that each diode is of silicon (Si) and its potential barrier is 0.7 volt, and forward-resistance is .