The DC bias voltage must be blocked from entering the tuned circuit. In electronicsa varicap diodevaractor diodevariable capacitance diodevariable reactance diode or tuning diode is a type of diode designed to exploit the voltage-dependent capacitance of a reverse-biased p—n junction. Original uploader was Adiasmesquita at pt. This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it.
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The DC bias voltage must be blocked from entering the tuned circuit. In electronicsa varicap diodevaractor diodevariable capacitance diodevariable reactance diode or tuning diode is a type of diode designed to exploit the voltage-dependent capacitance of a reverse-biased p—n junction. Original uploader was Adiasmesquita at pt.
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. Another common configuration uses two back-to-back anode to anode varicap diodes.
A third circuit, at top right in diagram, uses two series-connected varicaps and separate DC and AC signal ground connections. Views Read Edit View history. This reduces the overall capacitance and the capacitance range by half, but has the advantage of reducing the Doido component of voltage across each device and has symmetrical distortion should the AC component possess enough amplitude to bias the varicaps into forward conduction.
They are commonly used in voltage-controlled varifapparametric amplifiersand frequency multipliers. Generally the use of a varicap varicwp in a circuit requires connecting it to a tuned circuitusually in parallel with any existing capacitance or inductance. This is done to keep costs down — two dual packages could have been used, one for the tank and one for the oscillator, four diodes in all, and this is what was depicted in the application data for the LAN AM radio chip.
This is a retouched picturewhich means that it has been digitally altered from its original version. Microelectronic circuits 6th ed. File:Diodo — Wikimedia Commons Internal structure of a varicap. When in the high capacitance state, usually with low or no bias, they present a low impedance path to RF, whereas when reverse biased their capacitance abruptly decreases and their RF impedance increases.
Public domain Public domain false false. From Wikimedia Commons, the free media repository. The DC ground is shown as a traditional ground symbol, and the AC ground as an open triangle. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. September Learn how and when to remove this template message. In some applications, such as harmonic multiplicationa large signal amplitude alternating voltage is applied across a varicap to deliberately vary the vsricap at signal rate to generate higher harmonics, which are extracted through filtering.
Some designs of electronic security tag readers used in retail outlets require these high capacitance varicaps in their voltage-controlled oscillators. From Wikipedia, siodo free encyclopedia. Although they are still slightly conductive to the RF path, the attenuation they introduce decreases the unwanted signal to an acceptably low level. The following other wikis use this file: This page was last edited on 12 Novemberat Diodo varicap em diferentes encapsulamentos.
Wikipedia articles needing clarification from May Articles needing additional references from September All articles needing additional references Wikipedia articles needing clarification from January Commons category link is on Wikidata Wikipedia articles with GND identifiers. Potentiometer digital Variable doido Varicap. Popular makeshift varicaps include LEDs,  1NX series rectifier diodes,  Schottky rectifiers and various transistors used with their collector-base junctions reverse biased,  particularly the 2N and BC These circuit configurations are quite common in television tuners and electronically tuned broadcast AM and FM receivers, as well as other communications equipment and industrial equipment.
JPG This section does not cite any sources. All following user names refer to it. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong. All diodes exhibit this variable junction garicap, but varactors are manufactured to exploit the effect and increase the capacitance variation.
Please help improve dlodo section by adding citations to reliable sources. Capacitor types Ceramic resonator Crystal oscillator Inductor Parametron Relay reed relay mercury switch. In case this is not legally possible: This page was last edited on 28 Augustat These types were — and still are — extensively used in television tuners, whose high carrier frequencies require only small changes in capacitance.