Varactor diodes are also referred to as varicaps or tuning diodes. Varactor diode or varicap provides voltage controlled variable capacitance. The varactor diode is manufactured in such as way that it shows better transition capacitance property than the ordinary diodes. In this video tutorial, the presenter would be explaining about varactor diode, it’s working, and its applications. It is a device whose capacitance changes with the variation in the applied reverse bias potential.It is also known as varicap or voltcap. A diode is effectively like a valve for an electrical circuit. Working System Of Varactor Diode: How a Varactor Diode Works First one needs to understand the working principle of a changeable capacitor. Varactor Diode Definition: The diode whose internal capacitance varies with the variation of the reverse voltage such type of diode is known as the Varactor diode. Varactor diode Applications : Varactor diode is used in FM radio and TV receivers . This diode delivers the net variable capacitance in parallel resonant bandpass filter. Usually, this is provided by microprocessor control through the digital to analog converter. Increase in reverse bias of varactor diode increases the capacitance as shown in the figure below. Application of Varactor Diode in VCOs The oscillator can be enabled by turning the diode D1. INTRODUCTION Varactor diode is a special type of PN junction diode, in which PN junction capacitance is controlled using reverse bias voltage. Applications of the Varactor Diode There is no useful purpose of varactor diode operated when it is operated in forward bias. Varactor Diode. Using this circuitry we can set the frequency through varying the voltage. Required fields are marked *. 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! Metal contact is provided for the connection with battery. By using voltage control technique in the varactor diode circuit, varying capacitance can be provided. The symbol of varactor diode is shown in the figure. In the receive front end circuits, tracking filters may be essential. The story begins with our tagline “ज्ञानम् परमं” (Knowledge is Supreme), which has been  subsequently becoming our brand. In Fig b, the bias on D 1 is set by the voltage divider which is made up of R 1 and R 2. The varactor diodes are small in size and hence, they are very light weight. The obvious varactor diode considerations are: (a) Capacitance value (b) Voltage (c) Variation in capacitance with voltage. 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. When investigating high performance varactor diodes for specific RF applications, the terms, abrupt and hyperabrupt varactor diodes will often be seen. In microwave receiver LO, varactor diodes can be used as frequency multipliers. These devices are commonly used in communication systems. Save my name, email, and website in this browser for the next time I comment. These are special purpose diodes, also called a varicap diodes or tuning diodes or variable capacitance diodes, designed to work always in reverse bias state. 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. The function of the varactor diode is to use the principle of variable capacitance between PN junctions to make semiconductor devices, which are used as variable capacitors in high-frequency tuning and communication circuits. The varactor diodes enable the filters to track the incoming received signal frequency which can be controlled using a control voltage. As a result these diodes are also referred to as varicaps, tuning diodes, voltage variable capacitor diodes, parametric diodes and variable capacitor diodes. The region of depletion is considered to be the dielectric. It acts like variable capacitance in reverse bias operation. 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 … The Varactor diodes belong to the family of semiconductor devices. It works on reverse biased mode. 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. Varactor diode is used in a mobile network system. Your email address will not be published. One side is seen from the positive while the other side is … 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 produces considerably less noise compared to other conventional diodes. 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. The capacitance is controlled by applied voltage. When run with a AC small signal that have a high DC offset, it functions ver… 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/ The V-I characteristics of the diode are non-linear and it permits the flow of current in only one di… Glass passivation is provided to create a shell that protects from corrosion. To understand the working principle of the varactor diode, we must know what is a capacitor and how can we change the capacitance. A few other important applications of varactor diodes can be listed as follows: Your email address will not be published. A Varactor Diode is a PN junction diode that is especially operated in reverse biased mode. A varactor diode is also called varicap diode. Here, varactor diode consists of two lines at one end (cathode end of normal diode) that indicates the capacitor symbol. 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. The CV characteristics of a typical Varactor diode and its symbols are shown in the below figure. The capacitor C1 is used to prevent the reverse bias for the varactor diode, also avoids the diode getting short-circuited through the inductor. 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. Working: Varactor diode is used as voltage controlled capacitor Fig1 Internal structure of Varactor diode. In general, electronic circuits can be built with a various electrical and electronic components like resistors, capacitors, diodes, transistors, integrated circuits, transformers, Thyristors, etc. The varactor diode can be tuned by applying tuning voltage or bias through an isolating series resistor R1. These diodes begin conducting electricity only if a certain threshold voltage is present in the forward direction (i.e. Let us discuss about the diode which is a two terminal electrical device. If the varactor diode reverse voltage is increased, then the depletion region size increases. 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. And ensure that varactor diode is not affected by the bias voltage or any other voltages in the circuit. Varactor Diode Modulator. Fig5. The junction capacitance depends on the applied voltage and junction design. A voltage variable capacitance of a reverse biased junction can be termed as a Varactor diode. Lets look into the construction, working of diode, characteristics and applications of varactor diode Varactor diodes can be used as frequency modulators. Varactor diodes are reverse biased diodes. The varactor diode modulator circuit is shown in Fig5. It is used for storing the charge. Varactor diodes are used to vary the capacitance in variable resonant tank LC circuits. Let us consider the capacitor that consists of two plates separated by an insulating dielectric as shown in the figure. e use everywhere from the audio frequencies to the outer reaches of the extreme microwave frequencies. In this video, what is varactor diode, it's working, the applications and some important specifications are explained. 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. The capacitor in a circuit can be replaced with the varactor diode, but it is essential to ensure the tune voltage, i.e. Variable capacitance leads to the origination of the varactor diode. 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. You very well know that if distance between the two plates of capacitor is increased than its capacity reduces. 2. Varactor diode 1. Similarly, if the varactor diode reverse voltage is decreased, then the depletion region size decreases or narrows. Usually either R 1 or R 2 is made variable so that the center carrier frequency can be adjusted over a narrow range. 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. As a result these diodes are also referred to as varicaps, tuning diodes, voltage variable capacitor diodes, parametric diodes and variable capacitor diodes. The varactor diodes can be used to tune the filters. Semiconductor diodes are the most common type of diode. A varactor diode works as follows: A basic diode consists of p-type and n-type materials which are considered as the conducting plates. Digital Modulation Techniques: Electronics Engineering Notes pdf ppt, The Common-collector Amplifier Configuration Notes for Electronics Engineering 1st Year, Unity Gain Buffer/Unit Follower Notes for Electronics Engineering 1st Year, B.Tech./1Sem/Computer System and Programming in C, Fundamentals of Clamping Circuit Notes for Electronics Engineering 1st Year, Principle of Nicol Prism Engineering Physics B.Tech 1st Year, Zeolite Process for Water Softening and its Limitation Notes pdf ppt. The property of varying capacitance is utilized to achieve a change in the phase of an electrical circuit or in the frequency. 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. Varactor Diode is a reverse biased p-n junction diode, whose capacitance can be varied electrically. 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. Varactor diodes can be used as RF phase shifters. The CV characteristics of a typical Varactor diode and its symbols are shown in the following figure. Opposite to it if distance between the two plates is reduced than dielectric between them will also reduce and due to which its capacity increases. These diodes are specially manufactured and optimized such that they enables a very high range of changes in capacitance. When varactor diode is connected with the resonant circuitry as shown in the below figure it operates like a variable capacitor. 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 amount of charge that accumulates … the “low resistance” direction). What is Varactor Diode? 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. 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. Definition of a Varactor Diode: “The term varactor is the shortened form of a variable reactor, which refers to the voltage-variable capacitance of a reverse-biased p-n junction.” Varactor diode is also known as a variable diode, vericap diode, tuning diode, variable reactance diode, or variable capacitance diode. The region of depletion is an important factor in determining the value of capacitance. The P-N Junction diode creates capacitor effect. The varactor diode was named because of the variable reactor or variable reactance or variable capacitor or variable capacitance property of these diodes. 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. the voltage required to set the varactor diode capacitance. It is also known as Varicap diode (Variable Capacitance). Varactor diodes are used along with reactance modulator to provide automatic frequency correction for an FM transmitter. The capacitor C1 is used to prevent the reverse bias for the varactor diode, also avoids the diode getting short-circuited through the inductor. for generation of FM wave. The varactor diode is one type of PN junction diode whose internal capacitance changes with the applied reverse bias voltage. 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: What is Varactor Diode Working of the Varactor Diode Equivalent Circuit of the Varactor Diode Important Specifications of the Varactor Diode Applications of… 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. The depletion region between the P-type and N-type regions can be considered as insulating dielectric. A varactor is a non-microphonic, comp;1ct, electronically var­ iable capacitor whose capacitance can be rea