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   Diodes, Tuning

A varicap diode, varactor diode or tuning diode is a type of diode used in electronic circuits.

Varactors are commonly used in parametric amplifiers, parametric oscillators and voltage-controlled oscillators as part of phase-locked loops and frequency synthesisers.It is principally used as a voltage-controlled capacitor, and its diode function is secondary.

Varactors are operated reverse-biased so no current flows , but since the width of the depletion zone varies with the applied bias voltage, the capacitance of the diode can be made to vary. Generally, the depletion region width is proportional to the square root of the applied voltage; and capacitance is inversely proportional to the depletion region width. Thus, the capacitance is inversely proportional to the square root of applied voltage.

All diodes exhibit this phenomenon to some degree, but specially made varactor diodes exploit the effect to boost the capacitance and variability range achieved - most diode fabrication attempts to achieve the opposite.



Bronze Partners
A.P.I. Electronics, Inc.
Freescale Semiconductor, Inc.
Jaro Components, Inc.
Khandelwal Herrmann Electronics Ltd
Knox Company
M/A-COM Tyco Electronics
MicroMetrics, Inc.
Microsemi Corp
Microwave Device Technology
New Jersey Semi-Conductor Products
Philips ECG
Semiconwell
Semitronics Corp
Skyworks Solutions, Inc
Sprague-Goodman Electronics, Inc.
Toko America, Inc.
Toshiba America Electronic Components, Inc.
Tyco Electronics Corp.
Ventronics, Inc.
Vishay Intertechnology
Zetex, Inc.
Fixed and programmable amplifiers - Frequency Devices

 

Books
Tunable External Cavity Diode Lasers: Tunable Semiconductor Diode Lasers
Cunyun Ye

Excerpt - page 4: "... output fiber [Berger and Anthon (2003)]. 1.3.2 Tunable external cavity diode lasers There are many possible ... laser for accomplishing the widely tuning of diode laser. Tunable external cavity diode laser system consists ..."
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Instrument Development for Atmospheric Research and Monitoring: Lidar Profiling, Doas and Tunable Diode Laser Spectroscopy (Transport and Chemical Transformation ... of Pollutants in the Troposphere, V. 8)
Jens Bosenberg, David Brassington, and Paul C. Simon

Excerpt - page 293: "... K. Reference cells are filled with concentrated gases for precisely tuning the diode lasers to the chosen gas absorption lines. Tropospheric air is ..."
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Bistabilities and Nonlinearities in Laser Diodes (Artech House Optoelectronics Library)
Hitoshi Kawaguchi

Excerpt - page 294: "... Am Tunable Wavelength Filter Using a Phase-Shift-Controlled Distributed Feedback Laser Diode With a Wide Tuning Range and a High Constant Gain," Appl. Phys. Lett., Vol. ..."
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Microwave and Millimeter-Wave Diode Frequency Multipliers (Artech House Microwave Library)
Marek T. Faber, Jerzy Chramiec, and Miroslaw E. Adamski

Excerpt - page 13: "... input or output frequency may be changed at a given tuning setting) and its tuning bandwidth. Harmonics and Subkarmonics Content Elementary analysis of diode frequency multipliers given by (2.1) through (2.5) shows that a ..."
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Handbook of Distributed Feedback Laser Diodes (Optoelectronics Library S.)
Geert Morthier and Patrick Vankwikelberge

Excerpt - page 25: "... control. If DBR lasers are equipped with a phase control tuning section (see Figure 1.13), wavelength ... popular devices as wavelength-tunable laser diodes. However, DFB lasers also lend themselves to wavelength tuning [21]. ..."
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Ultrafast Diode Lasers: Fundamentals and Applications (Artech House Optoelectronics Library)
Peter Vasil'ev

Excerpt - page 26: "... MULTIPLE-CONTACT LASERS This section is devoted to another type of diode lasers that are often used for ultrashort optical pulse generation and wavelength tuning. Due to specific features of semiconductor technology it is possible ..."
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Distributed Feedback Laser Diodes and Optical Tunable Filters
H. Ghafouri-Shiraz

Frequency Stabilization of Semiconductor Laser Diodes (Artech House Optoelectronics Library)
Tetsuhiko Ikegami, Shoichi Sudo, and Yoshihisa Sakai

Laser Diode Microsystems (Microtechnology and MEMS)
Hans Zappe

Tab Electronics Guide to Understanding Electricity and Electronics
G. Randy Slone

Excerpt - page 207: "... pE Virtually every modern television and radio receiver incorporates varactor diodes for tuning purposes, to reduce costs and to improve long-term performance by ..."
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Sneaky Uses for Everyday Things: How to Turn a Penny into a Radio, Make a Flood Alarm with an Aspirin, Change
Cy Tymony

Excerpt - page 70: "... capaci-tor) Note: In some radios you may not see the diodes near a tuning transformer, but the adjustment can still be performed. See Figure ..."
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The Kingfisher Science Encyclopedia (Kingfisher Science Encyclopedia)
Charles Taylor

Excerpt - page 364: "... tape. Later, operators recognized the sounds as letters. N Crysta Diode Tuning capaci is simple radio is called a crystal set. ..."
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The Measurement, Instrumentation and Sensors Handbook
John G. Webster

Excerpt - page 1341: "... use of the capacitive effect of the reversed-biased p-n junction diode. By applying different reverse bias ... varactor diodes are in the tuning circuits in radio frequency receivers. Present-day varactor diodes operate into ..."
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Design of Analog CMOS Integrated Circuits
Behzad Razavi

Excerpt - page 523: "... high resistivity, creating a resistance in series with the reverse-biased diode and lowering the quality factor ... the tank and limiting the tuning range. The diode is therefore represented as shown in Fig. ..."
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Audio and Hi-Fi Handbook
Ian Sinclair

Excerpt - page 213: "... previous discussion is the general use of dual (back-to-back) Varicap diodes. These are preferred to single diodes as the tuning method in high-quality systems because they avoid the distortion of ..."
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Teach Yourself Electricity and Electronics, Fourth Edition (Teach Yourself)
Stan Gibilisco

Excerpt - page 326: "... still build a crystal set today, using a simple RF diode, a coil, a tuning capac- itor, a headset, and a long-wire antenna. Notice that ..."
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The Electronics of Radio
David Rutledge

Excerpt - page 355: "... cores Motorola - http://mot2.indirect.com 1N5817 Schottky barrier rectifier MVAM108 silicon tuning diode P2N2222A general purpose npn silicon transistor 2N3553 2.5-W high frequency ..."
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Microstrip Antennas: The Analysis and Design of Microstrip Antennas and Arrays
David M. Pozar and Daniel H. Schaubert

Excerpt - page 150: "... circularly polarized antenna have been built by using microwave switching diodes instead of machine screws for shorting posts. These antennas verified that diode tuning can be used for precise control of the frequency and ..."
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Software Defined Radio: Enabling Technologies
Walter H.W. Tuttlebee and Walter Tuttlebee

Excerpt - page 54: "... if account were taken of increased power levels (e.g. varactor diode tuning will probably be precluded because of the nonlinearities such devices ..."
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The Beginner's Handbook of Amateur Radio
Clay Laster

Excerpt - page 167: "... transistors used in amateur radio and other electronic Typical varactor tuning diode tuning circuit. equipment. Transistors at the top of the photograph ..."
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Secrets of RF Circuit Design
Joseph J. Carr

Excerpt - page 119: "... (L1) resonates with a capacitance made up of Cl (main tuning), C2 (trimmer tuning or bandspread), ... on a voltage variable-capacitance ("varactor") diode for the tuning function. The total tuning capacitance that resonates ..."
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Building Electro-Optical Systems: Making It All Work
Philip C. D. Hobbs

Excerpt - page 71: "... range and are prepared to hunt. Stick with the IR diodes if you need to do anything fancy. 2.12.4 Mode Jumps The tuning of diode lasers is discontinuous in both temperature and current, ..."
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Rfic and Mmic Design and Technology (Iee Circuits, Devices and Systems Series, 13)
I. D. Robertson and S. Lucyszyn

Excerpt - page 268: "... varies from -0.4 to -1.2 V. The frequency versus voltage tuning characteristic is plotted in Figure ... which uses a single varactor diode as the tuning element, is shown in Figure 6.11. The ..."
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Audio Electronics, Second Edition
John Linsley Hood

Excerpt - page 114: "... previous discussion is the general use of dual (back-to-back) Varicap diodes. These are preferred to single diodes as the tuning method in high-quality systems because they avoid the distortion of ..."
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Solid-State Laser Engineering (Springer Series in Optical Sciences)
Walter Koechner

Excerpt - page 258: "... adjustments between the two lasers is performed by tem- perature tuning of the monolithic diode-pumped laser crystal in the master oscil- lator. Frequency sensitivity to ..."
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Building Scientific Apparatus
John H. Moore, Christopher C. Davis, Michael A. Coplan, and Sandra C. Greer

Excerpt - page 253: "... (PUMPED WITH ION LASERS, FREQUENCY DOUBLED TLSAPPHIRE, AND FREQUENCY DOUBLED DIODE LASERS) Tuning Range' Power (W) Linewidth Supplier Tuning Rangea Power (W) Linewidth ..."
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Understanding Love: Part II - The Roads of Light
Panicos Sardos

Excerpt - page 226: "... "relative reality of truth." The peculiar situation is that all diodes and tuning gateways lead to the centre which is Christ Logos. Whetherwe ..."
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Frequency Synthesis by Phase Lock
William F. Egan

Excerpt - page 38: "... where foot is the oscillator frequency and u2 is the tuning voltage. Gain Kv is sometimes called the modulation sensitivity. It ..."
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Characterization and Measurement of Magnetic Materials (Electromagnetism)
Fausto Fiorillo

Excerpt - page 230: "... in advanced commercial devices) using different detector coils and varactor diodes as tuning capacitors. The input stage of the if. amplifier in the ..."
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The Arrl Antenna Book (19th Ed./Bk&CD-ROM)
R. Dean Straw

Excerpt - page 88: "... micas this is not usually a problem. But if variable-capacitance diodes are used to remotely tune the loop, pay particular attention to the manufacturer's specification for Q of the diode at the frequency of operation. The tuning diodes can have a significant effect on circuit Q. Now ..."
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Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits
Thomas H. Lee

Excerpt - page 282: "... available commercially). As a consequence, hyperabrupt doping profiles can produce diodes whose capacitance varies over a decade range. Such diodes permit the tuning of LC oscillators over a 3 : I frequency range, ..."
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Advances in Microstrip and Printed Antennas
Kai Fong Lee and Wei Chen

Excerpt - page 437: "... Hall, and J. S. Dahele, "Active Patch Antenna Element with Diode Tuning," Electron Lett., Vol. 27, No. 20, pp. 1846-1847, 1991. [83] ..."
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Teach Yourself Electricity and Electronics
Stan Gibilisco

Excerpt - page 371: "... still build a crystal set today, using a simple RF diode, a coil, a tuning capacitor, a headset, and a long-wire antenna. Notice that there's ..."
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Build Your Own Low-Power Transmitters: Projects for the Electronics Experimenter
Rudolf F. Graf and William Sheets

Excerpt - page 91: "... BARE WIRE Figure 15-6 ATVC900 Parts Placement Component Side C23 TUNING DIODE D1 Figure 15-7 ATVC900 Parts Placement Solder Side 178 ..."
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Audio/Video Professional's Field Manual
Jerry C. Whitaker

Excerpt - page 20: "... reduce noise and equalize the voltage distribution across the individual diodes (Figure 1.14). Tuning diodes have a controlled re,, erse capacitance that varies w ..."
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Transmitter Hunting
Joseph D. Moell and Thomas N. Curlee

Excerpt - page 221: "... is filtered and controls the frequency of the VCO via tuning diode D2, closing the loop. Regulator transistor Q1 supplies stabilized + ..."
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Electronic Filters, Amplifiers & Oscillators - Frequency Devices
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