Varactor diode Applications : Varactor diode is used in FM radio and TV receivers . The size of the depletion region of diode changes with change in reverse bias. Varactor diode is a semi-conductor device in which the junction capacitance can be varied as a function of the reverse bias of the diode. What is Varactor Diode? If the varactor diode reverse voltage is increased, then the depletion region size increases. The amount of charge that accumulates … In this video, what is varactor diode, it's working, the applications and some important specifications are explained. By using voltage control technique in the varactor diode circuit, varying capacitance can be provided. Varactor Diode. If the junction is reverse biased, the mobile carriers deplete the junction, resulting in some capacitance, where the diode behaves as a capacitor, with junction acting as a dielectric. In electronics, a varicap diode, varactor diode, variable capacitance diode, variable reactance diode or tuning diode is a type of diode designed to exploit the voltage … VARACTOR DIODE Nyamador Enock Seth University of Mines and Technology (UMaT), Tarkwa Computer Science and Engineering ‘14 Twitter: @enock4seth 2. The varactor diode is manufactured in such as way that it shows better transition capacitance property than the ordinary diodes. To learn how a varactor diode works, you need to first understand the working principle of a variable capacitor:A capacitor consists of two conducting surfaces separated by a non-conducting dielectric medium (see figure below). It is a device whose capacitance changes with the variation in the applied reverse bias potential.It is also known as varicap or voltcap. Varactor diodes can be used as RF phase shifters. This diode delivers the net variable capacitance in parallel resonant bandpass filter. Varactor Diode is also known as Tuning Diode, Variable Reactance Diode, Varicap Diode or variable capacitance diode. These diodes have a p-n-n+ structure, where the applied voltage modulates the width of the depletion region between the p and n+ sides. 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. As a result these diodes are also referred to as varicaps, tuning diodes, voltage variable capacitor diodes, parametric diodes and variable capacitor diodes. ..... Our Mantra: Information is Opportunity. Varactor diode is also a semiconductor microwave solid-state device, it is frequently used in applications where variable capacitance is desired which can be achieved by controlling voltage. Varactor diode is also sometimes referred to as varicap diode, tuning diode, variable reactance diode, or variable capacitance diode. It works on reverse biased mode. the “low resistance” direction). “Never doubt that a small group of thoughtful, committed, citizens can change the world. 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. 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. Varactor diode or varicap provides voltage controlled variable capacitance. The varactor diode was named because of the variable reactor or variable reactance or variable capacitor or variable capacitance property of these diodes. in general, it looks like a normal PN- junction diode in which one terminal is termed as the cathode and the other terminal is termed as anode. And, these are termed as abrupt varactor diodes, gallium arsenide varactor diodes, and hyper abrupt varactor diodes. The varactor diode can be tuned by applying tuning voltage or bias through an isolating series resistor R1. These devices are commonly used in communication systems. The capacitor C1 is used to prevent the reverse bias for the varactor diode, also avoids the diode getting short-circuited through the inductor. Definition: Varactor diode is the one which works on the principle of variation in capacitance by changing the width of the depletion region of P-N junction. The story begins with our tagline “ज्ञानम् परमं” (Knowledge is Supreme), which has been  subsequently becoming our brand. A varactor diode is also called varicap diode. Varactor diodes are used along with reactance modulator to provide automatic frequency correction for an FM transmitter. In this video tutorial, the presenter would be explaining about varactor diode, it’s working, and its applications. At the base we have heatsink to moderate the temperature of the diode and for cooling purpose. By watching this video, you will learn the following topics:0:21 What is Varactor Diode1:23 Working of the Varactor Diode5:19 Equivalent Circuit of the Varactor Diode6:28 Important Specifications of the Varactor Diode9:01 Applications of the Varactor DiodeWhat is Varactor Diode :The varactor diode is one type of PN junction diodes whose internal capacitance changes with the applied reverse bias voltage. The depletion region between the P-type and N-type regions can be considered as insulating dielectric. The same thing can also be seen in the varactor diode. The varactor diode acts like a variable capacitor under reverse bias. The capacitance is controlled by applied voltage. The varactor diodes can be used to tune the filters. The capacitor C1 is used to prevent the reverse bias for the varactor diode, also avoids the diode getting short-circuited through the inductor. A diode is effectively like a valve for an electrical circuit. Varactor diodes are also referred to as varicaps or tuning diodes. Save my name, email, and website in this browser for the next time I comment. When one of surfaces is connected to a positive voltage and the other to negative voltage, because of attraction between positive and negative carriers, positive charge accumulates on one surface and negative charge on the other. Fig1 Internal structure of Varactor diode. Lets look into the construction, working of diode, characteristics and applications of varactor diode What is Varactor diode, How Varactor diode works, Electronic Devices & Circuits, Engineer Concepts. The varactor diode can be tuned by applying tuning voltage or bias through an isolating series resistor R1. The word varicap is originated from the combination of word variable and capacitor. Let us consider the capacitor that consists of two plates separated by an insulating dielectric as shown in the figure. The symbol of varactor diode is shown in the figure. When run with a AC small signal that have a high DC offset, it functions ver… Varactor diodes can be used as frequency modulators. The  oscillator can be enabled by turning the diode D1. Usually either R 1 or R 2 is made variable so that the center carrier frequency can be adjusted over a narrow range. 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! The capacitance of D 1, of course, is controlled by two factors: a fixed dc bias and the modulating signal. 2. When varactor diode is reverse biased than the neutral region between P and N layers increases and when the reverse biasing is decreases then this neutral region is also decreased. for generation of FM wave. In the receive front end circuits, tracking filters may be essential. The varactor diodes enable the filters to track the incoming received signal frequency which can be controlled using a control voltage. In Fig b, the bias on D 1 is set by the voltage divider which is made up of R 1 and R 2. Glass passivation is provided to create a shell that protects from corrosion. The CV characteristics of a typical Varactor diode and its symbols are shown in the following figure. The varactor diode symbol consists of the capacitor symbol at one end of the diode that represents the variable capacitor characteristics of the varactor diodes. The capacitor uses two surfaces that separate from the insulating dielectric. Let us discuss about the diode which is a two terminal electrical device. The junction capacitance depends on the applied voltage and junction design. Varactor diode 1. Even though the variable capacitance effect can be exhibited by the normal diodes (P-N junction diodes), but, varactor diodes are preferred for giving the desired capacitance changes as they are special types of diodes. You very well know that if distance between the two plates of capacitor is increased than its capacity reduces. A Varactor Diode is a PN junction diode that is especially operated in reverse biased mode. Varactor diodes produces considerably less noise compared to other conventional diodes. It is also known as Varicap diode (Variable Capacitance). The region of depletion is considered to be the dielectric. One side is seen from the positive while the other side is … Indeed, it is the only thing that ever has.” …………and we strongly believe on …, Theory of Varactor Diode Notes for Electronics Engineering 1st Year, on Theory of Varactor Diode Notes for Electronics Engineering 1st Year, Theory of Light Emitting Diodes Notes for Electronics Engineering, Tunnel diode Working principle and characteristics Notes for Electronics Engineering 1st Year. It is also known as Varicap diode (Variable Capacitance).Applications of the Varactor Diode1) Voltage Controlled Oscillator2) Phase and Frequency Modulators3) RF Filters4) FM Receivers and other telecommunication receivers (For tuning)Important Specifications of the Varactor Diode:1) Capacitance Range2) Capacitance Ratio3) Reverse Current (Leakage current)4) Breakdown Voltage5) Quality FactorThis video will be helpful to everyone in understanding the varactor diode.#VaractorDiodeFollow my second channel:https://www.youtube.com/channel/UCGA2TO8ylVqFHpucwn_6JlwFollow me on Facebook:https://www.facebook.com/ALLABOUTELECRONICS/Follow me on Instagram:https://www.instagram.com/all_about.electronics/Music Credit:http://www.bensound.com/ Increase in reverse bias of varactor diode increases the capacitance as shown in the figure below. Using this circuitry we can set the frequency through varying the voltage. A varactor diode is a semiconductor diode whose junction capacitance varies linearly with applied voltage when the diode is reverse biased. As a result these diodes are also referred to as varicaps, tuning diodes, voltage variable capacitor diodes, parametric diodes and variable capacitor diodes. In this video, what is varactor diode, it's working, the applications and some important specifications are explained. There is no useful purpose of varactor diode operated when it is operated in forward bias. Application of Varactor Diode in VCOs The oscillator can be enabled by turning the diode D1. It acts like variable capacitance in reverse bias operation. Varactor Diode is a reverse biased p-n junction diode, whose capacitance can be varied electrically. Varactor diodes are again classified into various types based on the varactor diode junction properties. The varactor diode always works in reverse bias, and it is a voltage-dependent semiconductor device Your email address will not be published. e use everywhere from the audio frequencies to the outer reaches of the extreme microwave frequencies. Varactor Diode Modulator. A varactor diode works as follows: A basic diode consists of p-type and n-type materials which are considered as the conducting plates. 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. Varactor diodes are specially designed to take advantage of this characteristic and are used as Voltage Controlled capacitors rather than traditional diodes. A varactor is a non-microphonic, comp;1ct, electronically var­ iable capacitor whose capacitance can be rea