1000 Threads found on edaboard.com: Variable Capacitor
where can i find these circuits and whats the theory behind them?
the theory behind it is mentioned by Davood Amerion
this concept is mainly used in the ICs or VLSI so that it is not practical to integrate a FM radio in one IC and to connect the IC by a variable cap. at the same size as the hole device :?:. So that we should replace it by a
Electronic Elementary Questions :: 01-15-2006 17:31 :: airman :: Replies: 5 :: Views: 1425
Thank for Hughes's and sengyee88's help.
But except that measure can I implement variable cap. in other easy way?
hspice supports voltage-controlled capacitors. But for spectre, you need veriloga.
Analog IC Design and Layout :: 10-19-2006 19:56 :: Hughes :: Replies: 8 :: Views: 2464
I want to generate a variable capacitor in cadence such as the Cs in figure below.
Cs is changing its capacitive value in a frequncy of 1kHz.
I try making a Cs using VerilogA language. But this can only generate varible current. have found a paper about generate a varable capacitor
Analog Circuit Design :: 10-23-2006 07:47 :: Davidy :: Replies: 2 :: Views: 3678
I would second the idea of a bank of comutated fixed inductors + varicap
But then the question is: what application do you need this variable L and C for?
Analog Circuit Design :: 10-19-2007 02:41 :: kender :: Replies: 7 :: Views: 2126
voltage controlled variable capacitor diodes (VVC)
What is it ?
plz help me.
RF, Microwave, Antennas and Optics :: 07-09-2008 09:20 :: elsalvador :: Replies: 2 :: Views: 1313
I have trouble simulating a variable capacitor that is a function of time, for example C=Co*Cos(w*t). I personally only know this software can allow me to have a time dependent capacitor, but if other softwares are available that can also do the same thing I am more than happy to learn them. But for now, can anyone who has (...)
Software Problems, Hints and Reviews :: 01-07-2010 01:57 :: sl50 :: Replies: 0 :: Views: 1368
I built an oscillator from a design I found in an issue of the ARRL publication, "QST" magazine. I found that the frequency stopped varying when I turned the variable capacitor after a while, although it worked when I first built it. I couldn't find anything wrong with the circuit so, guessing that the trimcap went bad, I soldered in a (...)
Hobby Circuits and Small Projects Problems :: 04-16-2010 21:47 :: obrien135 :: Replies: 2 :: Views: 1470
You have to use a plastic screwdriver (it can be buyed in every electronics shop) because the metallic one cannot be used for a variable capacitor.
Is not a problem of your project but of the metallic screwdriver
RF, Microwave, Antennas and Optics :: 06-29-2010 15:05 :: mauroferrari_ :: Replies: 11 :: Views: 1589
i am unable to use the variable capacitor in my circuits,i.e, which pin of variable capacitor should be connected to which point in circuit?76193
Analog Circuit Design :: 06-22-2012 10:36 :: mk16820 :: Replies: 3 :: Views: 1076
I have been trying to make a variable capacitor based off of a lookup table in PSPICE. I found a paper by cadence, A Nonlinear capacitor Model for Use in PSpice, which gives a method of creating a variable capacitor but I am unsure how to actually write the .lib file to implement this design.
Analog Circuit Design :: 07-27-2012 17:44 :: carlmarx :: Replies: 2 :: Views: 885
I need to design a variable capacitor SPICE model. I want to do it with look-up table which would contain a C-V characteristic. Can it be done?
I simulated a IDC with HFSS and now I want to include the results in Spice model. I never used Spice so I do not know how to do it. Can you help me?
Analog Circuit Design :: 10-10-2012 05:23 :: vfurlan :: Replies: 0 :: Views: 637
i want to have a variable capacitor in ads.this capacitor is a model of a mems microphone.please help me
and help me for matching this capacitor with microphone amplifier
thanks for your help
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i want to have a capacitor that variable with voltage and have a flat (...)
RF, Microwave, Antennas and Optics :: 10-22-2012 04:31 :: javad ahmadi :: Replies: 2 :: Views: 270
I need variable capacitor, working at 1-2GHz, with capacitance of 1-5pF. I hope the Q
is high enough, such as 200. Can you recommend? Thanks.
RF, Microwave, Antennas and Optics :: 05-11-2014 21:20 :: amicloud :: Replies: 4 :: Views: 248
How can we design a variable resistor and capacitor in cmos technology.i am talking about resistance of value between 30Mohms upto a 1 Gohm and cpacitance values between some hundred femto farads and few picofarads.
Please suggest possible ways about how this can be done.Any material in this regard would be useful.
Analog Circuit Design :: 02-27-2008 10:55 :: hacksgen :: Replies: 2 :: Views: 2002
I think it was just to allow flexibility in the wiring layout; in pre-PCB days the wiring was "point-to-point" and a choice of connection point would have been useful since variable capacitors could be mounted in different ways.
Both connection points could be used for different components if the chassis layout made that convenient.
You don't hav
RF, Microwave, Antennas and Optics :: 07-12-2012 21:22 :: krp :: Replies: 3 :: Views: 981
I'm trying to design reader device for RFID applications. But important thing is that frequency will be variable. For this purposes I can use to options: either for different frequencies use separated output stage with chosen value of capacitor or use one output stage and somehow vary capacitance. What is also important: i use microc
RF, Microwave, Antennas and Optics :: 01-18-2013 07:04 :: GeniusRus88 :: Replies: 5 :: Views: 525
Check out AN-271 and AN-344 from National, for ideas on how to build digitally-controlled capacitance multipliers.
I cannot find AN-344 any longer on their website, I only have the hard-copy.
Anyway, check out page 5 of the datasheet for this part, that was used in AN-344.
Electronic Elementary Questions :: 11-17-2005 21:03 :: VVV :: Replies: 3 :: Views: 4313
i want to have a capacitor in ADS that its value change with frequency. how can i do this?
RF, Microwave, Antennas and Optics :: 01-11-2008 13:51 :: sedighe :: Replies: 4 :: Views: 1544
I think the pins are O=oscillator, A=antenna and G=ground. They refer to the larger values variable capacitors inside the module. The letter 'F' before them signifies 'FM', a reference to the FM broadcast band. They are lower value variable capacitors on the same shaft.
If you need ones labeled FO and FA, but all you have (...)
Analog Circuit Design :: 02-21-2010 12:00 :: betwixt :: Replies: 13 :: Views: 665
variable capacitor 100 pF have 3 pin, i need datasheet for its and pin configuration?
RF, Microwave, Antennas and Optics :: 07-29-2011 04:06 :: Riski Andami Nafa :: Replies: 1 :: Views: 1874
Here is most commonly used ways to control capacitance value.
variable capacitor - Wikipedia, the free encyclopedia
Varicap - Wikipedia, the free encyclopedia
connecting capacitors in serial or parallel with electronic or mechanical switches
Microcontrollers :: 08-31-2011 01:57 :: kak111 :: Replies: 1 :: Views: 302
That "common" connection in the centre is actually connected to the spindle, so in that circuit, when you touch the knob on the spindle you will be adding extra capacity across the bottom capacitor. Just use one section of the variable capacitor, WITH THE CENTRE CONTACT earthed, and wire a fixed 68Pf in series with it.
Analog Circuit Design :: 06-22-2012 13:11 :: chuckey :: Replies: 5 :: Views: 540
Maybe this can give you some ideas :
Hobby Circuits and Small Projects Problems :: 04-10-2013 12:47 :: tpetar :: Replies: 2 :: Views: 865
Does anyone know any recent technologies that allow for a variable capacitor with Inductor with high Q . I have seen MEMS - anything else?
RF, Microwave, Antennas and Optics :: 11-12-2013 22:00 :: jf1020 :: Replies: 1 :: Views: 141
are you using t*s*m*c process?
that's no way to design a "perfect" VCO, but only fit to the specification.
Since the VCO is for 802.11b, should it be 2.45GHz or multiple of it. In this case, you should use LC VCO for its low-phase noise and high prefequency performance.
To start the design, you should have the relevant components,
RF, Microwave, Antennas and Optics :: 06-28-2003 06:07 :: RC13 :: Replies: 1 :: Views: 1349
MOS-FET capacitor is already used in memmory device fabrication. A junction capacitor inside each MOS can be used for storing at least one bit of memmory.
Other applications use MOS-FET capacitor in order to get variable capacitor as varactors, for example, inside the MOS LC oscillator.
Electronic Elementary Questions :: 07-08-2004 23:35 :: mazelk :: Replies: 3 :: Views: 1217
can any body tell me how to tune the rlc (series) and lc (parallel) so that the frequency would be maximum circuit changing the capacitor using variable capacitor?? what do we use, where do we connect it and how?? thanx
RF, Microwave, Antennas and Optics :: 02-02-2005 09:10 :: huji :: Replies: 0 :: Views: 936
2-30p would rather suggest a variable capacitor of 2-30pF. It has 2 pads but on a schematic it may have 3 terminals..
Hobby Circuits and Small Projects Problems :: 02-28-2005 21:44 :: IanP :: Replies: 5 :: Views: 943
I tried this site and patch it to Proteus. I tried the variable air core inductor and variable capacitor. It doesn't work. Seems only the drawing is given but simulation is not supported.
Can anyone please provide a working simulation for air core variable inductance and variable (...)
Microcontrollers :: 08-27-2005 18:42 :: pete :: Replies: 2 :: Views: 1998
In cadence ic design tool, there is a sample for how to simulate differential LC VCO, it is under dfII/sampls directory. You can read the Spectre RF user guide for more help. For component selection, A-Mode varactor is a good device for variable capacitor, the inductor and active devices are dependent on what frequency your VCO is working on.
Analog IC Design and Layout :: 10-01-2005 02:52 :: pi331133 :: Replies: 8 :: Views: 6711
It's the oldest an simplest radio in MW range. If you add in parallel with the coil, a large (500 pF) variable capacitor, you can even tune it to different stations. It works better in the night. The inductor could be coreless but it need to be around 200 - 300 turns with 30 - 40 mm diameter for the coil shape. Earlier designs, instead of the diod
Electronic Elementary Questions :: 11-04-2005 01:58 :: marie65 :: Replies: 13 :: Views: 1243
Basically I patched two boards according to the provided schematics, one transmitter and one receiver. The variable capacitors for both boards are set at around 10nF so that the resonant frequency is around 120khz. (not exact)
If we assume that original TX oscillator did work reliably :
as schema is with common base based o
Electronic Elementary Questions :: 03-28-2006 10:55 :: artem :: Replies: 10 :: Views: 5101
Except the the circuit board and battery, all parts are from Mouser Electronics. A complete parts list with stock numbers is listed below. The circuit board is available through FAR Circuits. The variable capacitor is available through Electronix Express.
Because this is a superregenerative design, component
RF, Microwave, Antennas and Optics :: 04-24-2006 08:22 :: dunn :: Replies: 3 :: Views: 1240
I've been told an LED diode when it's reverse biased will act as a variable capacitor whose range is dependant on the amount of light falling on the diode junction. Does anyone have an approximate range of capacitance I would expect to find on a generic bright white LED?
Electronic Elementary Questions :: 05-01-2006 01:14 :: Sceadwian :: Replies: 7 :: Views: 2014
As far as I knew trimmer is a kind of variable capacitor.
Analog IC Design and Layout :: 05-16-2006 11:39 :: RollingEEE :: Replies: 6 :: Views: 2777
Generally we use a fixed inductor and a variable capacitor in FM tuner circuits.
Hobby Circuits and Small Projects Problems :: 09-10-2006 23:51 :: gunsuresh :: Replies: 1 :: Views: 884
I have a signal of video that have one modulation in FM at 10,7Mhz to send the status of one sensor.
How can eliminate a modulation of 10,7MHz of a signal? It is very important to do it with passive elements. It is possible to make a resonador LC in series to eliminate this frequency?
In order to adjust the resonador, is better to
Analog Circuit Design :: 03-21-2007 08:32 :: kkdelabaca :: Replies: 0 :: Views: 524
In the ancient days a paper tube was used for the coil form. The two coils were wound with close wire spacing. Then as part of the process of tuning in a station the separation between the two coils is adjusted.
The secondary inductance is determined by the variable capacitor capacitance range and the frequency range you want to tune in.
Electronic Elementary Questions :: 05-02-2007 09:58 :: flatulent :: Replies: 18 :: Views: 2216
I've build this oscillator and it works perfect but I need to switch the positions of the 2 variables capacitors to have the 15p-280p grounded (I have some Hf signals coming from antenna) The problem is when I permute the two CVs, I dont have the same frequency range ?? What can I do without changing the circuit? Thanks
RF, Microwave, Antennas and Optics :: 05-27-2007 09:35 :: falcone :: Replies: 3 :: Views: 1915
The usual values for L and C are chosen to give acceptable quality factor (low loss) at the working frequency ( series resistance << reactance << isolation resistance). This means reactance between tens of Ω and hundreds of Ω.
If you want to design a radio for brodcasting, you will use a standard variable capacitor, maybe taken
RF, Microwave, Antennas and Optics :: 09-09-2007 07:35 :: Eugen_E :: Replies: 5 :: Views: 816
You need to specify the center frequency. One method is to use variable capacitor diodes and a branch line coupler.
RF, Microwave, Antennas and Optics :: 02-15-2008 11:53 :: flatulent :: Replies: 4 :: Views: 1008
Your question is not quite clear.... I assume you want to know what topologies that are usuable for L and C band.
For L you can get away with both lumped (descrete) and distributed (stripline) but at C-band you are better off using stripline type. You can add a multi-turn variable capacitor to tune. A cheaper way would be to add a sma
RF, Microwave, Antennas and Optics :: 05-15-2008 18:05 :: webdog :: Replies: 6 :: Views: 794
i'm thinking of doing the separated vco for all the carrier frequencies stated above
i cant find any crystal oscillator for the vhf the solution...i'll try doin it with the variable capacitor and the inductor.....but i'm not so sure about the parameter such as
a-how to relate the freq and the values of the cap and inductor c
RF, Microwave, Antennas and Optics :: 09-03-2008 12:10 :: bend wh0nx :: Replies: 2 :: Views: 763
I have got an old short wave diathermy machine to be updated from analog control to digital one. It was made on 1996 by some students of undergraduate. I don't have any final year report as it was misplaced long ago. I am tracing schematic of that circuit, it's taking me time because it's too untidy and worst kind of wiring is done, which I never h
Analog Circuit Design :: 09-18-2008 18:41 :: umery2k75 :: Replies: 4 :: Views: 7417
The unit that I worked on, a long time ago, hooked up to a coil around a tokomak. We laid a flourescent light bulbe across the feed point to the coil, and adjusted the "tuning" knob inside the industrial RF signal generator in real time.
the tuning knob was probably connected to a high voltage variable capacitor of some sort that tried to match
RF, Microwave, Antennas and Optics :: 11-06-2008 08:18 :: biff44 :: Replies: 11 :: Views: 3135
Hello Guys ,
Please have a look at the following loop(15mm length 2mm thick) antenna for 432Mhz Transmitter hand held device ,which is for PCB. I want to know about the What value of variable capacitor to select (PCB is FR4 , 1.6mm thick standard).
2) Can loop
RF, Microwave, Antennas and Optics :: 03-28-2009 04:33 :: Trishool :: Replies: 4 :: Views: 1429
as we can tune in analog radios by changing the capacitane from variable capacitor but in digital radio like the radios in the mobiles how they tune themselves to required frequancy?
Digital communication :: 07-31-2009 06:50 :: hassanmd :: Replies: 1 :: Views: 718
may be this variable capacitor has two capacitors in one body, and they share the middle leg.The two capacitors can have different values.use only two legs for using one of the capacitors
Analog Circuit Design :: 11-22-2009 14:36 :: hameeds01 :: Replies: 3 :: Views: 1907
Use a Medium wave antenna coil, with ferrite rod. In absence, take 8mm ferrite rod, Large coil 32SWG Super enameled 80 turn. Small feedback coil 8 turn. Resistor-100K-10K Ohm, feedback capacitor 220pf. Connect 220pf capacitor parallel with PVC 2J Gang (variable capacitor) across +Vcc and Collector. Adjust. If require, vary (...)
Analog Circuit Design :: 04-15-2010 01:38 :: BADFLOPPY :: Replies: 3 :: Views: 1675
Just use any wire gauge - thicker would be better than thinner. The tap is one turn, so you make a turn, make a connection, then make the other three turns.
As the circuit is tuned by a variable capacitor, the inductance shouldn't be critical.
Digital communication :: 05-07-2010 08:14 :: keith1200rs :: Replies: 5 :: Views: 652