Varactor Diodes, also known as "variable reactance diodes", are made using the characteristic that the junction capacitance varies with the applied voltage when the PN junction is reverse biased. Hence they can be used in televisions in the resonant LC tank circuit. The advantages of varactor tuning are low power consumption, small size, and high tuning speed. Diodes provide many circuit functions (e. g., detection of signals, modulation of carrier frequencies with signal frequencies and subsequent demodulation) at high frequencies. ©2017-2020 ecstuff4u.com The content is copyrighted and may not be reproduced. The P-type material with holes (considered as positive) as majority carriers and N-type material with electrons (considered as negative charge) as majority carriers act as charged plates in the PN junctions. Diodes are also used as RF switches and as harmonic generators for efficient frequency multiplication. Also RF signal is present on the potentiometer, which is a disadvantage. Advantages of Varactor diode; Important applications of Variable diode; What is Varactor 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. Low Noise: It generates less noise as compared to the other P-N junction diode. Thus RW and R1 form a voltage divider which is used to measure the amount of reverse bias voltage across the varactor diode D1 and therefore its capacitance. Thus, the power loss due to noise is low in varactor diodes. This winding resistance of the inductor is in series with the potentiometer (R1). The TRAPATT diode is normally used as a microwave oscillator. As a result these diodes are also referred to as varicaps, tuning diodes, voltage variable capacitor diodes, parametric diodes and variable capacitor diodes. It is portable due to the small size and also a lightweight. Varactor Diode is a reverse biased p-n junction diode, whose capacitance can be varied electrically. SlideShare Explore ... variation. Some advantages of varactor diode is function of the voltage that impressed on its terminals. The V-I characteristics of the diode are non-linear and it permits the flow of current in only one direction In forward bias mode, the diode allows the flow of curren… In general, electronic circuits can be built with a various electrical and electronic components like resistors, capacitors, diodes, transistors, integrated circuits, transformers, Thyristors, etc. On the other hand, if we reduce the reverse voltage across the varactor diode, the width Wd of the depletion layer decreases. Therefore, the capacitance of the junction decreases. Varactor diodes are specially designed to take advantage of this characteristic and are used as Voltage Controlled capacitors rather than traditional diodes. It … It generates less noise as compared to other PN junction diode, It is portable due to the small size and  also a lightweight, It is reliable you can use it to vary a capacitance, These diodes are specially designed to work in the reverse-biased mode. The varactor diode produces less noise as less compared to the other diode. basica... Engineering is Humanity, Electronics is Religion. View Answer: Answer: Option B. When the reverse bias voltage increases, the junction capacitance decreases, on the contrary, the junction capacitance increases. Some advantages of varactor diode is function of the voltage that impressed on its terminals. variable diodes are lightweight and easily portable due to its small size. When the junction is forward biased, the barrier potential for these carriers decreases; so there is the notable amount of free carriers moving from this (electrons and holes), due to that moment it constitutes a current; hence large current can flow. Since in the depletion region there are no charge carriers, hence the zone acts as an. A varactor is always operated in reverse bias and it produces capacitance effect, this is because its anode and cathode terminals act as the plate of the capacitor and the free space between them acts as a. The inductor and the varactor diode form a parallel LC circuit. Reliability: It is more reliable than other P-N junction diodes. Advantages of Varactor Diode: The following are the few advantages of the varactor diode. Consider the PN junction, The P-type is consisting of free carriers which are called holes, and N-type is consisting of free carriers which are called electrons. A Diode is an electronic component that has two terminals and allows current to flow only in one direction. So, every P-N junction has a depletion region in between, and this depletion region width is dependent upon the voltage. We have learned that we can decrease or increase the junction capacitance of varactor- diode by changing the reverse bias voltages on the diode. The advantage of Schottky diode some of below It has a very low cut-in voltage of about 0.3 V. Schottky diode has very low switching time. Thus, by decreasing reverse bias will decrease the resonant frequency and vice-versa. The Varactor diodes belong to the family of semiconductor devices. So, we can conclude that the depletion layer width is dependent on the applied voltage. Its cathode has an extra capacitor, parallel two lines show the construction of capacitor and space between them shows a dielectric medium. Your email address will not be published. It is used in storing the charge. So, we can say its equivalent to a capacitor. The power loss due to noise is low. The function of the varactor diode is to store charges, so it is always operated in reverse bias condition. Let us discuss about the diode which is a two terminal electrical device. Hey Bostjan, Thanks for your comment, and this circuit just explains the basic concept behind voltage control tunning through tunnel diode, whereas the voltage divider is formed between R1 and Rw1 and also by varying inductor values we can change the resonant frequency of the Inductor Capacitor LC circuit. Some disadvantages are reverse-biased operated so no current flows. The varactor diode always works in reverse bias and it is voltage dependent semiconductor device. The hyperabrupt junction gives a much greater capacitance change for the given voltage change. The capacitor in a circuit can be replaced with the varactor diode, but it is essential to ensure the tune voltage, i.e. Cell splitting is a method of subdividing cell into the smaller sized cell. When a forward bias voltage is applied, the electric current flows, as a result, the depletion region becomes negligible, which is undesirable. ➨It is used to suppress voltage spikes. the power loss due to noise is low in varactor diodes. The price to be paid for these advantages are a relatively narrow tuning range of around 3% and a relatively low Q. A P-N junction diode which acts as a variable capacitor by changing reverse bias is known as a Varactor Diode. Now, since the depletion region has depleted all the carriers, we can consider this region as equivalent to two parallel plates of a capacitor within which we have sandwiched an insulator (Di-electric), No carriers exist there; so, it is an insulator. The resonant frequency Fr of the Inductor Capacitor LC circuit is given by: If the amount of reverse bias on varactor diode is increased, the value of Capacitance (C) of the varactor increases. Thereby, it creates a potential barrier; this is called the junction potential, and this potential barrier of a junction, happens to be around 0.5V to point 0.7 volts. Following are the benefits or advantages of Diode: ➨It functions as rectifier in order to convert alternating current into direct current. When the junction is reversed biased; the potential barrier is increasing; the reverse bias will help this potential barrier to get increased. As the reverse potential increases the width of the depletion region increases, which in turn reduces the capacitance. By adjusting the setting of a potentiometer (R1), we can vary the capacitance of diode easily. Working, Construction Applications (2019). Second, they exhibit relatively low turn on voltages. Transistor Configurations | Common Emitter, Base and Collector Circuits. ", Advantages and disadvantages of Zener diode, Advantages and disadvantages of tunnel diode, Advantages and disadvantages of Schottky diode, Advantages and disadvantages of an avalanche photodiode, Advantages and disadvantages of a photodiode, Advantages and disadvantages of full wave rectifier, Advantages and disadvantages of floppy disk, Umbrella cell approach in mobile communication, Advantages and disadvantages of Zigbee networks, Advantages and disadvantages of pulse width modulation, Difference between cell splitting and cell sectoring, Advantages and disadvantages of shielded twisted pair cable, Advantages and disadvantages of conduit wiring system, Difference between co-channel interference and adjacent channel interference. Indicate which of the following diodes will produce the highest pulsed power output: a. Varactor. The varactor diode can be tuned by applying tuning voltage or bias through an isolating series resistor R1. Reliability. For normal operation, a varactor diode is always operated in reverse bias as we studied. The capacitance of the varactor diode is generally small, … Low cost. This circuit cannot work in practice. Instead of the 0.6 to 0.7 volts seen with a silicon junction diode, a Schottky diode may turn on with as little as 0.2 or 0.3 volts. The resistance RW in the circuit is the resistance of inductor’s winding. It has small size and portable you can use it in circuits easily. In fact, this condition is shown in the picture above. King of physics constant pagl 11,570 views Here this article gives the advantages and disadvantages of the Zener diode to better understand this topic. Zener Diode Characteristics, Working and Practical Applications. Some disadvantages are reverse-biased operated so no current flows. It is basically similar to the UTP. When it is forward biased, the depletion layer width is decreased, and when it is reversed biased, the depletion layer width increases. Your email address will not be published. c. Schottky barrier. Note that the inductor is parallel with the capacitance of varactor diode. When run with a AC small signal that have a high DC offset, it functions ver… Advantages of Varactor Diode The following are the advantages of the varactor diode. A varactor diode is a simple variable capacitor that allows oscillator circuits and other circuits to be easily tuned by applying a voltage. Required fields are marked *, List of Top Best Schools in Pakistan 2020 (Updated), Powered by WordPress & Theme by StudentsHeart.com, Zener Diode , V-I Characteristics, Working, and Applications. It is one type of twisted pair cable. Moreover it is used to protect electronic components which are vulnerable to reverse voltages. The biggest advantage of the TRAPATT diode over the IMPATT diode is its. These devices are commonly used in communication systems. Powered by. Varactor diode construction. This reduces the overall capacitance and the capacitance range by half, but has the advantage of reducing the AC component of voltage across each device and has symmetrical distortion should the AC component possess enough amplitude to bias the varicaps into forward conduction. Consequently, the total capacitance of the junction is increased. It has very low power loss because varactor diode produces very low noise. so this circuit is perfect for the operation of voltage tunning. The increase in Capacitance will cause the resonant frequency Fr of the circuit to decrease. This, in turn, changes the resonant frequency of the Inductor Capacitor LC circuit. It is very low cost, thus it can be used in various electronic and electrical applications. Given fig: below shows the curve between reverse bias voltage VR across varactor diode and total junction capacitance CT. Zener diode consists of a highly doped reversed biased, p-n junction diode while operating in the breakdown region. o The Depletion region act as a capacitor di-electric because of its non conductive characteristic. The cell with low traffic speed is called as micro-cells and large high-speed traffic called macro-cells. b. higher efficiency. The capacitor C1 is used to prevent the reverse bias for the varactor diode, also avoids the diode getting short circuited through the inductor. Interference is the main problem in increasing capacity. The diode whose internal capacitance varies with the variation of reverse voltage such type of diode is known as the varactor diode. It has a small size. Solution: 12. But rectification is not all that a diode can do. diode - Duration: 29:42. The Schottky diode exhibits two major advantages over traditional diodes. ECSTUFF4U | ONLINE ELECTRONICS, ELECTRICAL ENGINEERING KNOWLEDGE | RESEARCH | INFORMATION |, Full forms related to Wireless communication, Full forms related to Satellite communication, Full forms related to Computer networking, Full forms related to Antenna and Wave Propagation, Full forms related to Optical communication, Full form related to Microprocessor X86 programming, Full form related to Digital signal processing. the voltage required to set the varactor diode capacitance. It generates less noise as compared to other P-N junction diode. Table 15.2 gives a comparison of the current state of … It generates very less noise as compared to others P-N junction diodes. The hyperabrupt diodes … They range from diodes with opti… tunnel Diode by King of physics . What is Varactor Diode | Construction, Working, Characteristics, And Applications, Download any E-Book for Free from Z-Library, varactor diode advantages and disadvantages, voltage controlling tuning circuit using Varactor diode, BARITT Diode? A varactor is used in Radio Receivers for tuning the circuit. The rectifier diodes are used in power supplies to convert a.c. voltage into d.c. voltage. As it exhibits voltage-controlled capacitance characteristic thus they have taken the place of mechanically tuned capacitors. The varactor diode is manufactured in such as way that it shows better transition capacitance property than the ordinary diodes. It has small size and portable you can use it in circuits easily. Given Fig: below shows the use of varactor diode in a tuned circuit. Schottky diode has very low power consumption. Varactor diode is also sometimes referred to as varicap diode, tuning diode, variable reactance diode, or variable capacitance diode. The property of varying capacitance is utilized to achieve a, When a P-N junction is formed, the depletion layer is created in the junction area. Applications of Varactor Diode: variable diodes are used in a variable resistant tank, which is generally an L-C circuit. Each switch has its own advantages and disadvantages. Topic: Varactor Diode Name: Abdul Mohiz Roll No: CS-15-41 2. o A varactor is a diode that always works /operates in reverse bias and is doped to maximize the inherent capacitance of depletion region. But unlike a zener diode they don’t allow the flow of current in zener breakdown regions. Applications of 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. It is economical. The varactor diode is made up of the p-type and n-type semiconductor. Varactor diodes are mostly used as tuned capacitors and they have significantly replaced mechanically tuned capacitors in various electronic applications. As a result hyperabrupt diodes are generally only used at lower microwave frequencies up to a few GHz at most. So, this region, where it is depleted of carriers, is called the depletion region. Because they have a tendency to merge with each other; the hole has a tendency to merge with the electron and vanish. A hexagonal cell  method is on... Zigbee network technology is a wireless protocol used for wireless networking and connectivity. The inductor has very low ohmic resistance and therefore cannot be practically used in a voltage divider. The oscillator can be enabled by tuning the diode D1. a. lower noise. The parent cell that was originally congested is called as mac... STP stands for shielded twisted pair cable. It is reliable you can use it to vary a capacitance. Tunnel Diode in hindi tunnel Diode by constant pagal . Lets look into the construction, working of diode, characteristics and applications of varactor diode . Varactor diodes are also referred to as varicaps or tuning diodes. Word Varactor is given to it due to its property of varying capacitance. Varactor Diode 7.15 Application of Varactor Diode 7.16 Shockley Diode INTR ODUCTION INTRODUCTION T he most common application of diodes is rectification. The following are the few Disadvantages of the varactor diodes. It starts conducting only when a junction potential is about 0.5V to 0.7 volts is applied, Until that time, current is negligible. Diode Clamper- Working of Positive, Negative Clamper Circuit. That means, more area in this gets depleted of carriers and this region widens. Since they are free carriers, when they are brought together, a junction is formed. 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