invented by Arthur Uhlir and A. Bakanowski
Light Emitting Diode - LED
diode is unipolar
what is the difference between reverse characteristics of zener diode and a practical diode ?
Diodes are measured in terms of resistance. The formula is as follows Rd = Vd / Id. That is Resistance of the diode = voltage across the diode to current flowing throught the diode.
There are a couple types of diode clamping-- A P-N diode was often used for clamping coils of relays that produce high voltages when the relays is de-energized. Bidirectional zeners are now the best solution. Diode clamping is also a term used to limit voltage excursions generally. Zener diodes are generally used for this purpose.
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
varactor diode is a correct answer
YES
It is called a varactor or a varicap diode. Its capacitance varies nonlinearly with the reverse voltage applied to its terminals.
Short answer: By using a varactor diode as the capacitance in a parallel resonant ckt, by changing the reverse bias voltage you change the value of capacitance which in turn changes the resonant frequency. This makes a tuneable resonant ckt.
The varactor diode is used in frequency tuning applications. Its effective capacitance is a function of the reverse bias voltage across it.
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. . .
Resonant frequency of a circuit is proportional to sq rt (L x C). A varactor diode, when suitably voltage biased, looks like a capacitor (C). Varying the bias varies the capacitor and thus the resonant frequency .
Varactor diodes are constructed in the same way as a capacitor and operate under reverse bias conditions, which gives rise to three current-conducting regions. Currents conduct through positive (P) and negative (N) regions, located at either end of the diode. Near the junction of the P and N regions, a depletion region ensures that no current carriers are available, thus acting as an insulator. Due to this arrangement, a varactor diode's conductive plates are separated by an insulatorlike dielectric, much like a capacitor Read more: Characteristics of Varactor Diodes | eHow http://www.ehow.com/list_6300842_characteristics-varactor-diodes.html#ixzz2UqM6t1Yi
Voltage controlled variable capacitor. Usually used for dynamic tuning of resonant circuits.
A varactor diode is most commonly used as the variable reactor. The varactor is a semiconductor pnjunction diode, and its junction capacitance is varied by the application of a steady signal from a local microwave oscillator, called the pump. Amplification of weak signal waves occurs through a nonlinear modulation or signal-mixing process which produces additional signal waves at other frequencies. This process may provide negative-resistance amplification for the applied signal wave and increased power in one or more of the new frequencies which are generated.
Varactor didoe is used as voltage controlled capacitor.it is generally used in reverse bias condition.