working of varactor diode

The varactor diode is a semiconductor device functions in a reverse bias and thus the capacitance of junction changes according to the varying applied voltage. Varactor diode is used in AFC circuits,self adjusting bridge circuits and adjustable bandpass filters; Varactor diode is used in tuning of LC resonant circuit in microwave frequency multipliers and in very low noise microwave parametric amplifiers. A varactor diode is considered as a special type of diode that is widely used in the electronics industry and is used in various electronics applications. “Never doubt that a small group of thoughtful, committed, citizens can change the world. In general, electronic circuits can be built with a various electrical and electronic components like resistors, capacitors, diodes, transistors, integrated circuits, transformers, Thyristors, etc. To understand the working principle of the varactor diode, we must know what is a capacitor and how can we change the capacitance. VARACTOR DIODE Nyamador Enock Seth University of Mines and Technology (UMaT), Tarkwa Computer Science and Engineering ‘14 Twitter: @enock4seth 2. The basic working of a varicap or a varactor diode can be understood with the following explanation: When a varactor or varicap diode is applied with a rising reverse bias potential, results in an increase in the depletion width of the device, which in turn causes its transition capacitance to decrease. These devices are commonly used in communication systems. Thus, it is exactly similar to the capacitor shown above. Varactor Diode is a reverse biased p-n junction diode, whose capacitance can be varied electrically. The symbol of varactor diode is shown in the figure. Your email address will not be published. It is well known that the operation of the p-n junction depends on the bias applied which can be either forward or reverse in characteristic. Applications of the Varactor Diode A few other important applications of varactor diodes can be listed as follows: Your email address will not be published. The story begins with our tagline “ज्ञानम् परमं” (Knowledge is Supreme), which has been  subsequently becoming our brand. Fig1 Internal structure of Varactor diode. When varactor diode is connected with the resonant circuitry as shown in the below figure it operates like a variable capacitor. And ensure that varactor diode is not affected by the bias voltage or any other voltages in the circuit. A varactor diode works as follows: A basic diode consists of p-type and n-type materials which are considered as the conducting plates. The varactor diodes have the following significant characteristics: Varactor diodes finds large number of applications within the RF design arena and it is difficult to discuss about all the applications of varactor diodes or varicap diodes. The varactor diode acts like a variable capacitor under reverse bias. These diodes have a similar structure as a p-n diode; the structure of a varactor diode is rather simple and illustrates its power as a component with nonlinear reactance. These diodes begin conducting electricity only if a certain threshold voltage is present in the forward direction (i.e. If the varactor diode reverse voltage is increased, then the depletion region size increases. Varactor diodes can be used as RF phase shifters. ..... Our Mantra: Information is Opportunity. The CV characteristics of a typical Varactor diode and its symbols are shown in the below figure. A Varactor Diode is a PN junction diode that is especially operated in reverse biased mode. The varactor diode was named because of the variable reactor or variable reactance or variable capacitor or variable capacitance property of these diodes. These terms relate to the junction and hence the performance of the varactor diode - hyperabrupt diodes, as the name suggests, having a very sharp change in doping that produces a very abrupt junction - in fact it is a hyperabrupt junction! A varactor diode is a simple variable capacitor that allows oscillator circuits and other circuits to be easily tuned by applying a voltage. Varactor diodes can be used as frequency modulators. Lets look into the construction, working of diode, characteristics and applications of varactor diode for generation of FM wave. At the base we have heatsink to moderate the temperature of the diode and for cooling purpose. These diodes are specially manufactured and optimized such that they enables a very high range of changes in capacitance. Varactor diodes produces considerably less noise compared to other conventional diodes. System of varactor diode or variable capacitance diode charge that accumulates … acts! 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