0
When p-n junction of a diode reversed biased then majority carriers are not able to cross the junction and are attracted in respective regions.So current becomes approximately zero.But because of minority carriers a reverse current keeps flowing.It is called Reverse Saturation Current.And due to attraction towards sides,charges go away from junction.So width of depletion reason increases.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoWhen both junctions of an npn transistor are reversed biased,the diode acts like an open switch.
Add your answer:
Earn +20 pts
What if a semiconductor diode is being tested using a digital multimeter and the resistance of the diode is 10 ohms in both forward and reverse-biased conditions is the diode shorted or opened?
The diode is neither shorted nor open. It is a zener diode and it is conducting in both directions. If it were truly shorted, it would read closer to zero ohms in both directions.
What is meant by reverse saturation current?
reverse saturation current is produced by the thermal activity of the diode materials. This current: 1- Is temprature dependant; that is, it increases as temprature. 2- Accounts fot the major portion of diode reverse current surface leakage current is produced by contamination on the surface of the device, allowing current flow to bypass the junction
How is an transistor used as a amplifier?
Voltage is applied between the collector and emitter. A signal is applied between the base and emitter. The input signal will control how much the transistor turns on and the larger current flowing across the Collector/Emitter will be the same, but larger, than the input. Therefore amplified.To keep the transistor switched on and to prevent the input signal switching it off, the transistor has to be biased on. This is usually done with a network of resistors on the base, raising the voltage to keep it conducting.
Discussion of zener diode a voltage regulation?
A zener diode has a relatively flat voltage to current curve when reverse biased. Within limits, you can consider that the voltage across the zener diode is constant. You can use the zener as the primary regulator, so long as you consider the power requirements and dissipation of both the zener and the load, and you do not overload the zener. More often, the zener is used as a voltage reference in a larger power supply that uses other components, linear or switched, to supply the load.
Why the current in zener diode is small in reverse biasing and why it is large in forward biasing?
A zener diode is designed to allow a current to flow through it in a direction that is reverse to the normal flow of current that would occur if it were used as a rectifier. Current can flow through a zener diode in both directions. In the forward direction, current will flow at a low voltage, usually about 1 volt. In the reverse direction, no current will flow until the voltage impressed across it is equal to the zener voltage. At this point, a current will flow and an extremely small increase in voltage will cause a large increase in current. Most importantly, it should be noted that the current flow through the zener diode is in the reverse direction to that of a normal rectifier. With the application of sufficient reverse voltage, a p-n junction will experience a rapid avalanche breakdown and conduct current in the reverse direction. Valence electrons which break free under the influence of the applied electric field can be accelerated enough that they can knock loose other electrons and the subsequent collisions quickly become an avalanche. When this process is taking place, very small changes in voltage can cause very large changes in current. The breakdown process depends upon the applied electric field, so by changing the thickness of the layer to which the voltage is applied, zener diodes can be formed which break down at voltages from about 4 volts to several hundred volts.
When both junctions of NPN diode are reverse biased then the diode is in which mode?
Transistor will be in OFF mode.
When both junctions of NPN diode are reverse biased then diode is in which mode?
Transistor will be in OFF mode.
When both junction of npn diode reverse biased the the diode in what state?
reverse biased
When the both junction of NPN diode is reverse biased then the diode is mode?
cutoff
When the both junction of npn diode is reverse biased then the diode in which mode?
Transistor will be in OFF mode.
What if a semiconductor diode is being tested using a digital multimeter and the resistance of the diode is 10 ohms in both forward and reverse-biased conditions is the diode shorted or opened?
The diode is neither shorted nor open. It is a zener diode and it is conducting in both directions. If it were truly shorted, it would read closer to zero ohms in both directions.
What is transistor action?
The transistor has three regions, emitter,base and collector. The base is much thinner than the emitter while the collector is wider than both. However for the sake of convenience the emitter and collector are usually shown to be of equal size. The transistor has two pn junctions that means it is like two diodes. The junction between emitter and base may be called emitter-base diode or simply the emitter diode.The junction between base and collector may be called collector-base diode or simply collector diode. The emitter diode is always forward biased and the collector diode is always reverse biased.
Is it necessary to add a series resistance with the diode or not?
if the diode is forward biasedwell practically the current flows in a circuit if and only if an effective resistance is present in the circuit, if we consider the diode to be ideal (barrier potential but no internal resistance) in this case an external resistance is required if we use the approximate model (both barrier potential and internal resistance are considered) we need not use an external resistance the internal resistance itself acts as the effective resistance.if the diode is reverse biased:-the same explanation applies even if the diode is reverse biased but one must take care that the reverse voltage drop on diode should not increase the peak inverse voltage mark the diode would be burnt or damaged if this phenomena occurs.So this can be prevented by adding suitable resistance to the circuit through which the voltage drop on diode can be managed
Is zener diode a linear device?
Zener diode is not a linear device... it is non-linear one. Since linear devices are those devices which have linear characteristics(V-I CHAR.), or follows the Ohm's law i.e. voltage is directly proportional to current. but in case of Zener diode ohm's law fails down. the V-I char. in both forward biased & reverse biased condition is non-linear. So. Zener diode is non-linear device
Operation of ttl gate with totem-pole output?
For the working of TTL nand with totempole When both inputs are LOW The emitter base junctions at A and B gets forward biased, base -collector junction gets reverse biased for Q1.So maximum current flows through forward biased junction. As base -collector junction of Q1 gets reverse-biased, base current through the Q2 is ZERO, which makes Q2 OFF. As Q2 is in OFF state, base current through Q4 is ZERO, which makes Q4 OFF.As Q2 is in OFF state the current through R2 flows through base of Q3 which makes Q3 and diode D to ON.As Q4 is in OFF state the current flows through the load, which make output to go HIGH state
Formula for peak inverse voltage?
piv:the maximum value of reverse voltage across a diode that occurs at the peak of the input cycle when the diode is reversed-biased.
What is meant by reverse saturation current?
reverse saturation current is produced by the thermal activity of the diode materials. This current: 1- Is temprature dependant; that is, it increases as temprature. 2- Accounts fot the major portion of diode reverse current surface leakage current is produced by contamination on the surface of the device, allowing current flow to bypass the junction
