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What is breakdown voltage of diode?
The critical value of the voltage, at which the breakdown of a P-N junction diode occurs is called the breakdown voltage.The breakdown voltage depends on the width of the depletion region, which, in turn, depends on the doping level. The junction offers almost zero resistance at the breakdown point.
What is dynamic resistance of diode?
The Current-Voltage relationship of a diode is not constant (not a straight line) and hence the resistance cannot be measured. Due to this non-linear nature of the the curve, there exists a unique value of resistance at every point of the curve which is called dynamic resistance (not static of constant resistance). The dynamic resistance equals the change in voltage divided by the change in current, when the voltage is changed by a small amount. In other words it is the slope of the graph of voltage against current. The dynamic resistance is different at different current values. About 30 years ago, and I do not remeber the brand or maker, there was a digital multimeter that DID measure dynamic resistance in diodes. It was a God Send for testing diodes in circuit. Diodes only conduct in one direction, so the device would show an open in one direction and a resistance under 1000 ohms on the other or a short (0 ohms).
What is the typical value of the barrier potential for a silicon diode?
Forward biase the given diode by using a Variable resistor in the circuit. By adjusting the value of variable resistor you will adjust the voltage being applied to junction diode. First adjust the resistance such that no(negligble) current flows through the circuit. Now start decreasing the value of resistance. Note the voltage across resistor(Vr) when current just starts flowing through the circuit. Then Potential barrier of diode will be: Vb=V-Vr Vb:Barrier Potential V:Battery Voltage Vr:Voltage Drop across resistance when current just starts flowing through the circuit.
Difference between zener diode and junction diode?
Zener diodes and ordinary junction diodes are similar, except that zener diodes have additional doping to bring their reverse breakdown voltage into a more usable value, and to allow them to not destructively avalanche when they do conduct in the reverse direction.
What is the typical value of the barrier potential for a germanium diode?
The typical value of the barrier potential for a germanium diode is around 0.3 to 0.4 volts. This barrier potential is the voltage required to overcome the potential barrier at the junction of the diode and allow current flow in the forward direction.
PN junction diode made of silicon is the value of voltage depends exponentially on the current through the diode.?
current depends exponentially on voltage: diode equation (approx.) Idiode=k (exp (Vdiode/Vth)-1) k=constant (saturation current, something like a femto ampère) Vth=KT/q => 25.8 mV @ T=300 K, Vth is thermal voltage K=Boltzmann's constant T=junction temperature (Kelvin) q=electron charge
Why resistor provides bias condition to the circuit?
A specified amount of current is allowed to flow through the diode. if the current passing through the diode exceeds the specific value, the diode gets heated and is likely to be damaged. therefore in a biasing circuit a resistance R has been applied , which limits the current passing through the diode within a specific value.
What is the behavior of a forward and reverse biased diode?
Forward Resistance:def: It is resistance offered by diode to the forward bias is known as forward resistance.This resistance is not the same for the flow of DC as for the changing current. Accordingly this resistance is of two types :1. DC FORWARD RESISTANCE.2. AC FORWARD RESISTANCE.1. DC forward resistance: It is the opposition by diode to the DC. It is measured by the ratio of DC voltages across the diode to the resulting DC current through it.2. AC forward resistance: It is the opposition offered by the diode to the changing current. It is measured by the ratio of change in voltage across diodes to the resulting change in current through diode. The AC forward resistance is more significant as the diodes are generally used with alternating voltage.Reverse Resistance:def: The resistance offered by the diode to the reverse bias is known as Reverse Resistance. It can be DC reverse resistance or AC reverse resistance depending upon whether the reverse bias is direct or changing voltage. Idealy the reverse resistance of a diode is infinte however in practice the reverse resistance is not infinite because for any value of reverse bias, there does exist a small leakage current. It may be emphasized their that reverse resistance is very large compared to the forward resistance.These Definitions are from PRINCIPLES OF ELECTRONICS by V.K MEHTA and ROHIT MEHTA
Why diode dose not allow to set voltage more than 0.7volts across it?
The barrier potential of the silicon diode is 0.7v if the applied voltage across it is more than this voltage then PN-junction of the diode breaks, once pn-junction breaks the voltage across the diode is constant, since it breaks at 0.7 this voltage will be constant and not exceed for any further increase in applied voltage -inform.mayaprasad@gmail.com The voltage across junction will only exceed from 0.7 volt (for silicon diode) in the case of reverse biasing the applied total voltage will appear across p-n junction. ANSWER: .7 VOLTS is an arbitrarily chosen number since a diode any diode have an exponential curve V vs I . This number is chosen when using a diodes but there are times when a greater or lesser voltage is chosen to reflect the application and the current trough the diode determine that. Example a diode gate diode will be chosen as .6 volts rather then .7v and a heavy conducting rectifier may have .8 volt to reflect closely the true value of the diode drop during real conditions
What happens if a silicon diode measures high value of resistance with the meter leads in both positions?
If the meter is developing more than the necessary forward breakdown voltage of the diode, typically 0.7 volts, then the diode is bad. However, some meters do not generate enough voltage in resistance mode to bias the diode on, unless you flip a switch that enables diode test mode. Use another meter at the same time to measure the voltage across the diode and compare that with the diode's published forward breakdown voltage.
What is the reverse recovery time of semiconductor diode?
When a diode passes from forward biased to reverse biased it takes a short period of time for the charge carriers in the vicinity of the junction to recombine and create a nonconducting depletion region. During this time period the diode conducts in the reverse direction, this is called the reverse recovery time. Its different for every kind of diode, to get the value for a specific diode consult the datasheet.
What is the importance of the reverse-to-forward resistance ratio of a diode?
to determine the comparison of resistance value of both forward and reverse diode . The more the resistance the lower the current , the lower the resistance the higher the current . When reverse bias , the resistance is high and it acts in open circuit and the reverse current is very small that can be neglected . When forward bias , the resistance is low and it acts as short circuit and the forward current is increasing as the voltage supply is higher .
