304 Threads found on edaboard.com: Miller Capacitance
basically, miller effect is the small g-d capacitance multiplied by the voltage gain at the drain. a high impedance at the drain gives a big miller multiplication. however, looking into a source is a very low impedance so the voltage gain, and consequently the miller effect, is smaller.
Analog IC Design and Layout :: 03.11.2006 19:15 :: electronrancher :: Replies: 7 :: Views: 5066
Do a web search on Google for "What is miller capacitance in MOSFETs" ..
miller capacitance is usually given as Cgd capacitance versus Drain to Source Voltage .. see example below ..
Analog Circuit Design :: 29.12.2006 03:25 :: IanP :: Replies: 5 :: Views: 5460
What is miller capacitance? Why it is used in Differential Amplifier?
Electronic Elementary Questions :: 26.01.2008 16:18 :: graciousparul :: Replies: 6 :: Views: 1735
what is the effect of miller capacitance on stability? if the miller effect dominates, does it mean that the positive zero is at very high frequency?
Analog Circuit Design :: 06.04.2008 17:01 :: kingmaker :: Replies: 0 :: Views: 394
How to calculate miller capacitance from the model parameters of a transistor that's biased up?
Another related question is that when I want to use simple equation to find a particular parameter, say use Cgs as part of ft expression, how to find this capacitance? Since there are Cgs, Csg (for Cgd, there is also Cdg)?
Analog Circuit Design :: 26.02.2011 07:24 :: cl254 :: Replies: 1 :: Views: 537
Can anybody help me on this feed forward compensation with no miller capacitance with some explainatory notes or materials.
thanks in advance.
Analog IC Design and Layout :: 12.05.2012 20:43 :: Saurabh Kamboj :: Replies: 2 :: Views: 208
cascode miller cap.
Analog Circuit Design :: 24.10.2005 05:51 :: sunking :: Replies: 2 :: Views: 473
Hi,when we consider a miller capcitance C connect between input and output,what we do is remove the capcitance and calculate the dc gain -A then the miller capcitance at the input is effectively (1+A)C.
Here comes my question,why should we use dc gain(so can we remove miller capcitance when calculating gain) here?If the frequency is high (...)
Analog IC Design and Layout :: 04.08.2007 17:02 :: leohart :: Replies: 16 :: Views: 1469
Yes, in single stage amp, output node will be dominant pole. But miller effect will push output node pole to high frequency that will worse the stability.
Analog IC Design and Layout :: 18.04.2008 16:57 :: leo_o2 :: Replies: 10 :: Views: 2397
If you use Hspice, then it is probably to use LX19(mn) to get information of miller effect.
Analog Circuit Design :: 30.05.2008 04:56 :: yschuang :: Replies: 5 :: Views: 869
How to decrease the miller Capacitor in a two-stage opamp which has a large gm at the input differential pair?
I think the reason for large Cc is as follows:
Since UGB is decided by gm/Cc, a very large Cc which is around 60 pF is used to move the UGB to a value which is lower than the second pole.
Is that right? And how t
Analog Circuit Design :: 10.06.2009 10:52 :: lallaby :: Replies: 5 :: Views: 759
Can someone actually use the miller effect to help them?
Analog Circuit Design :: 27.01.2010 07:30 :: patricky :: Replies: 4 :: Views: 1163
With a differential amplifier, can we tie capacitors (from output to input) in a positive feedback manner to get negative capacitance due to the miller effect? I heard it can be used in practice to negate the loading of the gate-to-drain capacitance at the input.
If this is the case, what prevents us from going so far to increasing this (...)
Analog IC Design and Layout :: 29.01.2010 08:12 :: patricky :: Replies: 9 :: Views: 1749
I want to calculate the output capacitance Co of a transconductor as depicted probleme i dont know how to do to calculate only Co without the contribution of the overlap capacitance
here is my
Analog Circuit Design :: 14.04.2010 19:10 :: MohEllayali :: Replies: 0 :: Views: 471
These are different things. One stage OTA, or rather an amplifying stage with one high impedance node, that is meant to work in a feedback configuration is compensated by a cap to ac ground. If you have a 2 stage amplifier you also have two poles which in uncompensated state are kind of close to each other. You can still compensate by a cap to grou
Analog IC Design and Layout :: 21.09.2010 20:06 :: sutapanaki :: Replies: 2 :: Views: 857
How to define the Cox. As my understanding, Cox is the constant parameter of a transistor. Can the simulator calculate is for me? If yes, I use the Spectre, which print parameter is refer to Cox.
the equivalent capacitance is better found using simulation (this is how std cell characterization tools
Analog Circuit Design :: 30.11.2011 06:25 :: tdf :: Replies: 10 :: Views: 1020
what is the difference between feedthrough and feedback capacitor? what is the meaning of this statement "CGD represents miller capacitance feedback while CDG represents miller capacitance feedback"
There are quite substantial differences!
1. A"feedthrough" capacitor is used to pass DC Current through a metal wall
RF, Microwave, Antennas and Optics :: 27.08.2012 17:32 :: jiripolivka :: Replies: 3 :: Views: 177
I have read about miller capacitance topic in odyseus's website but i dont understand what -G (nagative gain) mean. 180 phase shift??? How does this millter capacitance effect the input capacitance of a FET/transistor?
RF, Microwave, Antennas and Optics :: 20.05.2003 02:02 :: boy :: Replies: 2 :: Views: 853
Again good answers. There is just one slight thing that I don't quite agree with:
"...leading to higher electric field that draw more electrons , or it draws them at higher speed , from the channel to the drain end and hence increasing the drain current."
I don't think the depletion region field draws more electrons at a higher speed. To me the s
ASIC Design Methodologies and Tools (Digital) :: 08.10.2003 17:10 :: sutapanaki :: Replies: 9 :: Views: 2205
Thanks for your advices!
1. the pole and zero cancellation is not required that the zero= pole, it only need the pole is less than zero, then the magnitude is decreased by 40db/dec, but the phase is not it is not reqired a accurate resistor.
2. In razavi's book about the freq comp, which is almost talked about in miller comp between
Analog Circuit Design :: 17.06.2004 13:01 :: rambus_ddr :: Replies: 5 :: Views: 1385
Could anybody advise me on MOSFET driving circuit ?
The push/pull driver is very popular using a PNP and NPN transistor with bases tied together as the input and emitters tied together as the output. A low value of resistor around 22-100Ohms is conected from this output to the gate to prevent parasitic oscillations when swit
Analog Circuit Design :: 15.06.2004 07:30 :: E-design :: Replies: 10 :: Views: 3419
To further amplify (sorry for the pun) on the post above, look at the schematic for the extra lumped capacitance added to the circuit. It will usually be across the input/output of one of the stages. The miller effect stated in the previous post is used to make the time constant larger than if the capacitance was across a lumped resistor.
Analog Circuit Design :: 27.06.2004 04:11 :: flatulent :: Replies: 4 :: Views: 1994
miller effect: if a capacitor (C) is placed between input and output of an inverting amlifier,the equivalent input capacitance becomes (1+gain)*C
When the transistor is in common emmiter mode,the base-collector capacitance is this miller capacitor.Since the gain is high,the input capacitance is equals Cb-e+ (...)
Analog Circuit Design :: 15.07.2004 21:46 :: batdin :: Replies: 1 :: Views: 1097
my opinion is when a few limiting amplifier cascade together, the gain will increase from first stage to the last stage. As gain increase, the miller capacitance also increase according to formula cgd(1+A). This will form a even lower frequency pole as incresing stages, f=/2pi. RC. The output of the last stage will be
the dominant pole or the firs
Analog Circuit Design :: 19.11.2004 05:40 :: surianova :: Replies: 5 :: Views: 1268
it could be because:
at the cascoded node, you reduce the milled effect cap for the input. but at the same time you isolate the feedback resistor with that node. it means the output resistance is increase to (gm//gds).
i am assuming the feedback resistor is much less than gm//gds.. then the bandwidth at the cascoded node will be reduced..
Analog Circuit Design :: 21.03.2006 19:55 :: pengboy :: Replies: 2 :: Views: 844
If you need to drive large capactor or small resistance, a buffer wtih unit gain is addtion added to the classic 741 due to the effection with load to phsae margin.
I think the topology of 741 can meet you requriement of 121dB gain.
But i want to know what the UBW of the regualted 741 is and what you process is ?
Maybe the compensation of
Analog Circuit Design :: 15.02.2005 14:54 :: jiangwp :: Replies: 9 :: Views: 2660
You are not doing this the standard way that most circuits work best at. You need to find which stage has the lowest pole frequency and add to the miller capacitance by putting the capacitor from base to collector on that stage. This will lower the dominant pole. I would guess that this is the second gain stage where you have the capacitor from
Analog IC Design and Layout :: 18.02.2005 08:48 :: flatulent :: Replies: 4 :: Views: 766
input cap of your diff amp is Cox*W*L of your input device where Cox = eox / tox, plus miller cap (gain * Cgd). These two are the dominant caps you'll have to keep in mind for your freq response, poles and what have you.
Analog Circuit Design :: 08.04.2005 17:21 :: chinito :: Replies: 2 :: Views: 901
first - 200uV is exceptional! you can only hope that your chip has less than a few mV of ripple. try to look at it in terms of percent, and keep the percent lower than 1%... or 0.1% for extremely high accuracy.
say your full scale voltage in lock is 0.5v, you can endure 5mV steady state ripple before you reach the 1% region. and if your f
Analog Circuit Design :: 14.06.2005 07:55 :: electronrancher :: Replies: 12 :: Views: 3275
the equivalent circuit of a miller item lets say a gate-to-drain capacitance of a MOSFET is well know.
The effect of Cgs can be replaced by a gate to ground capacitance and a drain to ground capacitance with the equation given.
However, intuitively, I think this is only an approximation of the miller (...)
Analog Circuit Design :: 15.06.2005 08:59 :: sgperzoid :: Replies: 1 :: Views: 912
The desirable property of common base is that the base-collector capacitance goes from the output to ground and does not cause a miller effect or feedback that causes oscillations. The collector-emitter capacitance is much smaller. In the early days of large junction areas the common base circuit was commonly used at VHF.
Analog Circuit Design :: 31.07.2005 06:53 :: flatulent :: Replies: 7 :: Views: 778
I hope the following helps.
Voltage Divider Bias
- commonly used for biasing BJT single transistor amplifier, especially in a common-emitter configuration to provide for medium current gain and medium current gain.
- bias the base voltage so that you have a DC level for the input signal (AC) to swing.
- the resistors are selecte
Analog Circuit Design :: 16.08.2005 17:11 :: SkyHigh :: Replies: 10 :: Views: 3011
I know for amps, you have to look for miller capacitance (C) accross which there is the largest gain, then very often the dominant pole is 1/(A*C*R), A and R are the gain and resistance accross C, assuming A is large. For a common source, C is Cgd, for a two-stage op-amp, C is between the outputs of the two stages. I hope this helps.
Analog Circuit Design :: 22.08.2005 22:17 :: easytarget :: Replies: 6 :: Views: 752
I have designed a 6bit Pipelined ADC. However, I got some problem when i design the reference voltage circuit.
Because I have no output pad for VREFP(1.75V) and VREFN (1.25V) , so I add a large cap (about 400pF) on chip. I wonder which kind of OPAMP I should use.
For a one stage( folded) opamp, the large cap let the bandwidth very low ( about 1K
Analog Circuit Design :: 19.09.2005 11:02 :: Lantis :: Replies: 7 :: Views: 970
because the circuit is for digital signal, so it is not small signal operation.also remember for large signal operation the CL is nonlinear. but in digital circuit for a quick simulation, we usually define the equivalent CL.
therefore CL is not the same as differential amplifer. and also the equivalent CL changes depending on the operation of th
Analog IC Design and Layout :: 28.10.2005 19:56 :: pengboy :: Replies: 1 :: Views: 633
Cgd4 does not need to be accounted for the pole at Cgs3 and Cgs4, this is because a pole-zero doublet happens before the Cgd4 miller cap can take effect.
Analog Circuit Design :: 24.10.2005 07:39 :: willyboy19 :: Replies: 8 :: Views: 723
Don't just think use miller cap. Instead think by generating a zero through feed-forward.
Analog IC Design and Layout :: 12.03.2006 05:45 :: yaxazaa :: Replies: 38 :: Views: 4618
The place to start is the Gate-Source threshold voltage Vgs(th). Notice, however, that this parameter is the voltage at which the FET just starts to turn on. For the IRD530, this is specified at Id = 250 uA. Let's say you need an Id of 5A. From the definition of Forward transconductance, and using deltas instead of differentials, D
Analog Circuit Design :: 23.01.2006 22:51 :: Kral :: Replies: 20 :: Views: 17250
yes, voltage spike on the drain can effect the gate voltage. The reason for this is the gate-drain (miller) capacitance of the FET. Have you tried to limit the spikes on the drain by using a snubber circuit from drain to source? The snubber would either be a RC or a RC+diode circuit. Before putting anything else around the circuit I would
Analog Circuit Design :: 24.02.2006 04:09 :: v_c :: Replies: 6 :: Views: 1667
I'm using miller capacitance sample and hold cirucit.
For an 8-bit resolution my sample circuit must be able to detect and hold at least 12mV.
Right now I'm only able to make the resolution to 0.2V @ 200mV.
Can I get ant suggestion of how can i achive my targeted resolution.
Thanks in Advance.
Analog IC Design and Layout :: 24.02.2006 08:22 :: Syukri :: Replies: 5 :: Views: 1962
Well, due to miller effect, if there is a cap across an amplifying stage, the efective cap seen at the input and the output will be C*(1- Av) and C*(1-1/Av) respectively. Hence a negative capacitance can be realized. Makes sense here. Hence the negative capacitance at the input will try to cancel the gate-source (...)
Analog IC Design and Layout :: 18.04.2006 12:52 :: Vamsi Mocherla :: Replies: 10 :: Views: 2496
I think gate capacitance not depend on gate voltage,
both of Gate to Drain, and Gate to Source are fixed.
But because of miller effect cpacitor of GD can be appear very greater than initial value.
The gate capacitance is a huge function of gate voltage. See
Analog Circuit Design :: 24.04.2006 22:28 :: 10kangstroms :: Replies: 7 :: Views: 1673
If u r talkin about simple 2 stage opamp than this seems to be a strange config. for compensation .U can use simple miller capacitance b/w o/p of first and second stages.
And it is in such config. only that poles of two different node are affected due to change in value of compensation capacitor.
Analog Circuit Design :: 14.06.2006 11:47 :: engrvip :: Replies: 6 :: Views: 816
Well the thought of adopting GM-filter is a good choice and the other sugestion of using miller cap is also suggestion is to go for gm-filter.u can use the o/p impedance of the mosfets for this cause.if that is not enough u can use cascoding techniques to increase the R and decrease the C .
Analog Circuit Design :: 19.06.2006 09:21 :: venkateshr :: Replies: 2 :: Views: 462
Input cap. is moved closer to origin thereby reducing our 3-db BW(BW compensation0 and the op pole is (pole due to load cap & others) is moved away from the origin .Thus it is called as miller compensation or Pole splitting.
The reason for the movement of second pole is the decrease in the op resistance of
the second stage to a p
Analog Circuit Design :: 26.06.2006 12:30 :: venkateshr :: Replies: 8 :: Views: 981
...if anything, at the moment of the collector voltage increase, via the miller capacitance, the base of the transistor would see a current injection, which should turn the transistor on more. But this current overshoot indicates an opposite transient.
When we increase collector voltage:
Analog Circuit Design :: 04.07.2006 21:33 :: teteamigo :: Replies: 4 :: Views: 708
I have tried to design some distributed amplifier using the book by Virdee. I do have design examples using ADS. Let me try to find it. I have done it for few years. In Virdee's book they use a chip FET and use wire bound as inductors. I dont know this approach will be good up to 10 GHz or not. I would think that it is better if you can design it a
RF, Microwave, Antennas and Optics :: 18.08.2006 14:44 :: boy :: Replies: 16 :: Views: 3988
you can simulate the open loop frequence response of your amplifier, you can get the bode plot also get the unity gain freqency. At the unity gain freqency, you can the phase magin and then you can decide whether a miller cap is needed or not.
Analog Circuit Design :: 26.08.2006 03:31 :: pfd001 :: Replies: 3 :: Views: 1022
Who can tell me about miller Plateau?
Electronic Elementary Questions :: 16.11.2006 08:27 :: overmars :: Replies: 4 :: Views: 8968
It can also increase the bandwidth, due to reducig the miller capacitance. of the commen emitter/source amplifier.
Electronic Elementary Questions :: 06.12.2006 21:54 :: tyassin :: Replies: 4 :: Views: 628