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What is diffusion capacitance in pn junction?
A capacitor is a device that stores charge. Therefore any device that stores charges( static or dynamic) can be said to have capacitance. When a PN diode is forward biased, a current flows due to the majority charge carriers. At a particular instant there will be charges in motion. This is dynamic charge. The capacitance due to storage of dynamic charge is called the diffusion capacitance. We know that C = Q * V. That is capacitance is directly proportional to charge stored. Since the diode current increases exponentially with the voltage applied across it, the dynamic charge also increases exponentially . Hence the diffusion capacitance increases exponentially with the increasing diode voltage.
Application of varactor diode?
It includes RF design , parametric amplification ,fm, harmonic generators, voltage controlled oscillators ,in radio ,tv,cellular and wireless receivers ,and in electronic tuning .. That's it. . .
Why ordinary diodes dont work properly At high frequencies?
Because of stray capacitance. At very high frequencies, the inter-electrode capacitance has a low enough impedance that the diode no longer cuts off when reverse-biased, there is still significant conduction via capacitive coupling. High-frequency diodes are constructed so as to minimize this capacitance.
What is another name for depletion mode transistor?
depletion layer depletion zone juntion region space charge region bipolar transistor field effect transistor variable capacitance diode
What is a large slower acting diode?
it is a rectify diode
What is the explanation for the Operation of varicap diode?
The capacitance of a varicap diode varies as the reverse voltage to the diode changes. As you increase the reverse voltage, the capacitance decreases. And vice versa.
Why in a diode phase shift does not occur as it possesses diode capacitance?
Phase shift does occur, but the parasitic capacitance of a diode is so tiny compared to the external circuit resistance that it is virtually impossible to observe.
Why the laser diode has internal capacitance?
All real components have both parasitic capacitance and parasitic inductance.
What is pn junction capacitance?
The charge inside of a p-n diode with a connected voltage variety yields a capacitance is need to add circuit model of a p-n diode. The capacitance connected with the charge variety in the exhaustion layer is known as the intersection capacitance, in the same process capacitance connected with the abundance bearers in the semi impartial district is known as the dissemination capacitance.
Does the diffusion capacitance exit in forward biased diode?
Yes
Why transition capacitance called so?
Transition capacitance is the capacitance that is accumulated between two terminals as an electrical charge is carried between them. In a diode, this is the diffusion from anode to cathode of a diode in forward bias mode.
What is the value of the transition capacitance for a silicon diode when VD 0?
The transition capacitance of a silicon diode, often referred to as junction capacitance, depends on the applied voltage across the diode. When the diode is reverse-biased (VD < 0), the transition capacitance is positive and becomes larger as the reverse voltage increases. However, when VD = 0, the transition capacitance is at its minimum value, which can be approximated using the formula (C_j = \frac{\epsilon A}{W}), where (W) is the depletion width, (A) is the junction area, and (\epsilon) is the permittivity of the semiconductor material. At VD = 0, the depletion region is narrow, resulting in a relatively small capacitance.
What is verector diode in electronics?
I think you you are asking about varactor diode. varactor means variable capacitor. varactor diode is a p-n junction diode which provide a capacitance across it subjected to applied forward and reverse bias. means it provide variable capacitance which depends on the applied reverse voltage(mostly varactor diode works on reverse voltage).They are also known as varicap
Why is the diffusion capacitance is negligible for a reverse biased diode?
The diffusion capacitance in a diode is associated with the storage of minority carriers, which occurs primarily under forward bias. In reverse bias, the depletion region widens, and the majority carriers are pulled away from the junction, minimizing the injection and storage of minority carriers. As a result, the diffusion capacitance becomes negligible because there is insufficient minority carrier recombination and storage in this condition. Thus, the behavior of the diode under reverse bias is dominated by junction capacitance rather than diffusion capacitance.
What diode is used as voltage controlled capacitor?
It is called a varactor or a varicap diode. Its capacitance varies nonlinearly with the reverse voltage applied to its terminals.
Disadvantage of using diode as shunt element in clipper circuit?
In shunt clippers, when the diode is in off condition, transmission of input signal must take place to output. But in the case of high frequency input signals, diode capacitance affects the operation of circuit adversely and the signal gets attenuated (which means that, it passes through diode capacitance to ground).
What is meant by transition and space charge capacitance of a diode?
space charge region in a diode or say a bjt for better understanding is same as the depletion region, both transition capacitance and depletion capacitance are the same c= (epsilon*A)/d ; where ... c is capacitance A is area and d is the depletion width the other type of capacitance is the diffusion capacitance c= (T*I)/(n*V) where ... c is the capacitance T is transition ti me I is the drift current n is emission coefficient ... its value is 1 for germanium and V is thermal voltage .. 26mv
