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Topic: Variable capacitance diodes

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	U.S. Patent: 5311140 - Circuit for measuring variations in the capacitance of a variable capacitor using a ...
		A circuit for measuring variations in the capacitance of a variable capacr forming part of a sensor includes an oscillator which generates an alternating signal which is supplied to two branches of a detection bridge.
		The measurement circuit of the invention seeks to detect variations in the capacitance of the capacitor 1, enabling an electrical signal to be delivered which is representative of the measured magnitude.
		The common point B between between the capacitor 6 and the anode of the diode 7 is connected by means of a DC bias resistor 9 to a circuit 10 for applying DC bias to the point B and thus to the diode 7 for fixing the equilibrium point of the detection bridge.
	www.everypatent.com /comp/pat5311140.html (3420 words)

	Capacitor (Site not responding. Last check: 2007-10-24)
		In SI units, a capacitor has a capacitance of one farad when one coulomb of charge causes a potential difference of one volt across the plates.
		Hence, capacitive reactance is the negative imaginary component of impedance.
		Those that use the fact that the thickness of the depletion layer of a diode varies with the DC voltage across the diode.
	www.sciencedaily.com /encyclopedia/capacitor (3361 words)

	Varicap - Wikipedia, the free encyclopedia
		A varicap diode, varactor diode or tuning diode is a type of diode used in electronic circuits.
		It is principally used as a voltage-controlled capacitor, and its diode function is secondary.
		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.
	en.wikipedia.org /wiki/Variable_capacitance_diode (201 words)

	Capacitor - Wikipedia, the free encyclopedia
		Compared to bulk dielectric capacitors, this very thin dielectric allows for much more capacitance in the same unit volume, but maintaining the integrity of the dielectric usually requires the steady application of the correct polarity of direct current else the oxide layer will break down and be ruptured, causing the capacitor to fail.
		Variable capacitance is sometimes used to convert physical phenomena into electrical signals.
		Variable capacitance can be used to detect objects [proximity switch], or as the operating principle of a keyboard.
	en.wikipedia.org /wiki/Capacitor (4255 words)

	Electronic Components
		Variable capacitors or varactors are commonly employed in radio frequency (RF) tuning applications because the capacitance variations of the varactor caused by an applied voltage has corresponding effects on frequency tuning.
		The variable resistor basically includes an elongate electrical resistor which is connected across the supply voltage and a wiper slidable along the resistor in electrical contact with the resistor and electrically connected via a device to be controlled to one end of the resistor.
		Capacitance has been found to be inversely proportional to the thickness of the dielectric material, thus thin film capacitors are generally seen as a preferable means to achieve high performance.
	www.electronics-manufacturers.com /info/electronic-components (2116 words)

	Capacitor - Wikipedia, the free encyclopedia
		The capacitance is proportional to the surface area of the conducting plate and inversely proportional to the distance between the plates.
		Tolerances in capacitance value for discrete capacitors are usually specified as a percentage of the nominal value.
		Some forms of tank level gauge detect the change in capacitance between two electrodes which are immersed in a varying depth of liquid.
	en.wikipedia.org /wiki/Capacitors (4255 words)

	United States Patent Application: 0040090278
		The drain of the transistor P11 is connected to the gate of the transistor P12, to one end of the inductor L11, to the cathode of the variable-capacitance diode C11, to the drain of the transistor N11, and to the gates of the transistors N12 and N14.
		The drain of the transistor P12 is connected to the gate of the transistor P11, to one end of the inductor L12, to the cathode of the variable-capacitance diode C12, to the drain of the transistor N12, and to the gates of the transistors N11 and N13.
		In formulae (1), the variable L1 represents the inductance of the inductors L11 and L12, the variable L2 represents the inductance of the inductors L21 and L22, the variable C1 represents the capacitance of the variable-capacitance diodes C11 and C12, and the variable C2 represents the capacitance of the variable-capacitance diodes C21 and C22.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040090278".PGNR.&OS=DN/20040090278&RS=DN/20040090278 (4103 words)

	Patent 5575001: Direct broadcasting satellite tuner with a negative feedback and image compression circuit
		The opposite end of capacitance diode D6 is connected to capacitance diode D7, and connected through resistor R58 to power supply VT to control the oscillating frequency of voltage control oscillator 233.
		The input terminal of demodulator circuit 41 is connected to the output terminal of intermediate frequency amplifier unit 3, and the output terminal thereof is connected to the input terminal of baseband amplifier circuit 42.
		Variable capacitance diode VC101 receives the corrected feedback signal from phase correction circuit 43, and is controlled by V+to change the DC level of variable capacitance diode VC101 and then to send the feedback signal to voltage control oscillator 233 of microwave monolithic integrated circuit 23 for regulating its oscillating frequency.
	www.freepatentsonline.com /5575001.html (2670 words)

	HITACHI GLOBAL : News Releases from Headquarters : Feb 24, 2003
		Variable capacitance diodes are used in the electronic tuner circuitry of products such as TV sets and VCRs.
		Making use of the fact that their capacitance changes based on the voltage applied to them, they are employed in the selection of the wavelength to be received (the frequency allotted to the desired channel).
		Variable capacitance diodes generally have a drive voltage of about 25 volts, while TV sets and VCRs usually have a maximum power supply voltage of around 10 volts.
	www.hitachi.com /New/cnews/E/2003/0224/index.html (655 words)

	Variable tuning antenna and mobile wireless device using same patent invention
		In this antenna, a fixed inductance element 53 and a variable capacitance element 52 are connected to a radiation element 51 in series and the series resonance frequency is varied by varying the capacitance of the variable capacitance element 52.
		In other words, as the radiation element 51 is inductive and its capacitance is very small, taking La for the inductance of the radiation element 51, C for the capacitance of the variable capacitance element 52 and L for the inductance of the fixed inductance element 53, two equations are represented as follows.
		In this structure, a same variation of the capacitance can be achieved with a lower voltage and a higher variation rate over two times, because the combined capacitance becomes half compared to that in case of one diode, and therefore a precise adjustment can be obtained.
	www.freshpatents.com /Variable-tuning-antenna-and-mobile-wireless-device-using-same-dt20060907ptan20060197711.php (1395 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-10-24)
		Capacitive coupling is not normally employed where tuning over a very large frequency range is required, as is the case with the present circuit.
		At the input of each of the circuits of Figures 2 to 4, capacitor Cl and variable capacitance diode D1 are in parallel with an inductor L1.
		The diodes are reverse biased (as opposed to no bias) to reduce the stray capacitance of the diodes.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/84709.011108&ELEMENT_SET=DECL (2397 words)

	Diodes
		Diodes are the electrical version of a valve and early diodes were actually called valves.
		This breakdown voltage is the zener voltage for zener diodes.
		Germanium diodes such as the OA90 have a lower forward voltage drop of 0.2V (as opposed to the 0.6V drop of a Silicone based diode) and this makes them suitable to use in radio circuits as detectors which extract the audio signal from the weak radio signal.
	www.clivetec.0catch.com /Diodes.html (2093 words)

	All About Diodes
		Diodes can be used as voltage regulators, tuning devices in rf tuned circuits, frequency multiplying devices in rf circuits, mixing devices in rf circuits, switching applications or can be used to make logic decisions in digital circuits.
		The first diode in figure 1 is a semiconductor diode which could be a small signal diode sometimes used in switching applications, a rectifying diode or even a diode of the high power, high current stud mounting type.
		When a DC control voltage is applied to the common junction of the cathodes, the Capacitance exhibited by the diodes capacitance will vary in accordance with the applied voltage.
	www.electronictoolbox.com /All_about_Diodes.html (1861 words)

	Kids.net.au - Encyclopedia Capacitor -
		A capacitor has a capacitance of one farad when one coulomb of charge causes a potential difference of one volt across the plates.
		Important properties of capacitors, apart from the capacitance, are the maximum working voltage and the amount of energy lost in the dielectric.
		Those that use a mechanical construction to change the distance between the plates, or the surface of the area of the overlapping plates.
	www.kids.net.au /encyclopedia-wiki/ca/Capacitor (743 words)

	Tuning VFOs without air variable capacitors (Site not responding. Last check: 2007-10-24)
		The various diodes were connected to the oscillator by a series 100 pF NP0 ceramic capacitor at point A. In Figure 7, a 1N4007 is used as the tuning diode.
		Alternately a smaller capacitance may serve to limit the maximum capacitance of the VVC diode in the circuit that you are tuning.
		The Q for a given tuning diode varies with the reverse voltage and frequency of the oscillator and this is usually stipulated when the VVC diode is referenced.
	www.qrp.pops.net /pnj.htm (5187 words)

	High-Gain Preamp
		Diodes D1 and D2 are simply clamping diodes to protect the gate of the FET from high voltages that might appear on the antenna.
		The + side of the diodes, as indicated in the sketch showing the pinouts, goes to the common connection point of the diodes, where the tuning voltage is applied.
		Since the resonant frequency of the loop/capacitor combination is proportional to 1/C, a capacitance range of 10 to 1 will provide a tuning range of about 3 to 1 in frequency (limited at the high-frequency end by the internal parallel capacitance of the loop or inductor L1 in the preamp circuit).
	www.mlecmn.net /~lyle/preamp/preamp.htm (953 words)

	[No title]
		Special diodes are available that have enhanced capacitance and are known as variable capacitance diodes or varicaps for short.
		Diodes are never used in circuits where the circuit determines the voltage.
		Diodes are used in circuits where the circuit sets the current and the diode itself is allowed to set its own voltage drop.
	www.angelfire.com /planet/funwithtransistors/Basics_03_Sc_Diodes.html (3373 words)

	(WO 01/69687) ELECTRONIC COMPONENT COMPRISING VARIABLE CAPACITANCE DIODES, USE OF SAID COMPONENT IN A RECEIVING UNIT ... (Site not responding. Last check: 2007-10-24)
		The characteristic curve of the second diode is provided with a fixed, known ratio in relation to the characteristic curve of the first diode.
		The first diode (D1) and the second diode (D2) can be provided with the same variation ratio for instance which is the quotient of the greatest and the smallest adjustable capacity.
		Diodes (D1, D2, D3) having the same characteristic curve of different components (IC1, IC2, IC3, IC4) are arranged and switched in a partial receiving unit (VHF1, VHF2, UHF).
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/69687.010920 (276 words)

	The educational encyclopedia, Passive semiconductors and technology (Site not responding. Last check: 2007-10-24)
		Diode a diode is an electronic component that, in general, will pass current in only one direction (there are a few exceptions like zener and current regulator diodes)
		Diode characteristics plot the VI characteristics of a pn junction diode
		Varactors a varactor diode or varicap diode is also known as a variable capacitance diode or a varicap.
	users.telenet.be /educypedia/electronics/composemiconductorspassif.htm (738 words)

	Diode - HvWiki
		Diodes have a voltage drop, that is usually in the range of 0.3V to several volts depending on the diode.
		They did essentially the same thing as a silicon diode, but were much larger (a 250 amp 3 phase mercury rectifier would about 3 meters long and almost 50cm in diameter, compared to a silicon diode that would be less that 10cm square) and more delicate.
		Diodes are generally used to force current to go in one direction, although they can also be used to create a controlled voltage drop, regulate current, regulate voltage, and even provide light.
	wiki.4hv.org /index.php/Diode (1510 words)

	Sensors / Detectors: Capacitance Sensors
		AN9 Zetex Variable Capacitance Diodes: Zetec Semiconductors - Applications Notes - An introduction to the basic theory, an explanation of the important parameters, and typical applications are described within this note.
		The capacitance of a pair of wires (or a wire to a shield) is directly proportional to the length of the wire.
		Zetex Variable Capacitance Diodes: Zetec Semiconductors - Applications Notes - An introduction to the basic theory, an explanation of the important parameters, and typical applications are described within this note.
	www.discovercircuits.com /S/s-capacitance.htm (936 words)

	Electronics-DIY.com - NJM2035, BA1404, BH1415, BH1417, TDA7000, 38KHz Crystal, 7.6MHz Crystal, KV1310 BB105 BB109 ...
		MV104 is a variable capacitance diode that is used as a frequency tuning component in FM Radios, FM Transmitters, TVs, VHF Receivers, etc. MV104 varactor may be used as a replacement for KV1310, BB104, BB204 and BB304 varicap diodes.
		MV2105 is a variable capacitance diode that is used as a frequency tuning component in FM Radios, FM Transmitters, TVs, VHF Receivers, etc. MV2105 varicap may be used as a replacement for BB105 and BB205 varicap diodes.
		MV209 is a variable capacitance diode that is used as a frequency tuning component in FM Radios, FM Transmitters, TVs, VHF Receivers, etc. MV209 varicap may be used as a replacement for BB103 and BB109 varicap diodes.
	electronics-diy.com /components.php?sel=varicap_diodes (315 words)

	FM Radio Spectrum Analyzer
		As outlined in our proposal, we chose to use a variable capacitance diode, also known as a varactor diode, to control the tuner capacitance.
		The stray capacitance from the first and last stage will add to the capacitance in the tuner effectively changing the frequency we are tuning.
		To control the varactor diode, we were going to use a computer as outlined in proposal.
	www.nj.devry.edu /~jlee/fm_radio_spectrum_analyzer.htm (1822 words)

	Toko What's New (Site not responding. Last check: 2007-10-24)
		Mt. Prospect, IL - Toko's KV18XX series is a variable capacitance diode that is designed for use in low power communications equipment.
		Specifically, the diodes are available in a reverse voltage range of 1, 4, 6, 8, 10 and 25 volts.
		All devices feature a large capacitance ratio and capacitance that is very linear to the operational voltage range.
	www.toko.com /whats_new/kv18xx.asp (156 words)

	Final Project Report
		As outlined in our proposal, we chose to use a variable capacitance diode, also known as a varactor diode, to control the tuner capacitance.
		The table of capacitences provided the component values we needed, except the inductor was reduced to.1uH so that the capacitance values were all multiplied by 10.
		The stray capacitance from the first and last stage will add to the capacitance in the tuner effectively changing the frequency we are tuning.
	www.ee.washington.edu /circuit_archive/circuits/ee498/final/final.htm (1857 words)

	Physics and Astronomy Glossary
		The capacitance of a capacitor is measured by this procedure: Put equal and opposite charges on its plates and then measure the potential between the plates.
		Capacitance depends only on the geometry of the capacitor's physical structure and the dielectric constant of the material medium in which the capacitor's electric field exists.
		A prediction of the probable variability of a result, based on the inherent uncertainties in the data, found from a mathematical calculation of how the data uncertainties would, in combination, lead to uncertainty in the result.
	www.physlink.com /Reference/Glossary.cfm (8054 words)

	HITACHI GLOBAL : News Releases from Headquarters : Nov 26, 2001
		In addition, future plans call for extension of the lineup of various diodes to cover a wider application area including PDAs and notebook PCs.
		Variable capacitance diode: Characterized by variation of capacitance according to the applied reverse voltage.
		PIN diode: A diode in which an I layer (Intrinsic layer) is inserted between a P-type semiconductor and N-type semiconductor to form a PIN junction.
	www.hitachi.com /New/cnews/E/2001/1126a (503 words)

	Channel selection apparatus (Site not responding. Last check: 2007-10-24)
		The present invention relates to a channel selection voltages to be selectively applied to in tuner including a tuning element comprising a variable capacitance diode are preset by a plurality of potentiometers which are selectively actuated to select a desired channel.
		In recent years, many channel selection apparatus use a variable capacitance diode as a tuning element of a tuner and selects a channel selection voltage to be applied to the variable capacitance diode to select a desired channel.
		A selected one of those channel selection voltages BT is taken from a terminal 19 through one of diodes 18a to 18l, which is then impedance-converted by a transistor or the like (not shown) and applied to the variable capacitance diodes 3 and 11 of the VHF tuner 1 and the UHF tuner 2, respectively.
	www.sacnewsmonthly.com /invent/flame_spray_powder_mix/channel_selection.html (8047 words)

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