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73 Threads found on edaboard.com: Miller Capacitance
All transistors have miller capacitance which is from the inverting output to the input. In a differential amp , by adding caps by cross over ( From + out to + in and -out to -in ) from internal differential outputs, it tends to cancel the negative feedback with a lesser positive feedback with non inverting current or negative miller Effect (...)
The capacitance of a transistor and its wiring is a filter and produces negative feedback from the collector to its base due to the miller effect which reduces the hfe AC small signal current gain. The hFE DC small signal current gain is not affected so it is the highest. Fairchild's datasheet for the 2N3904 transistor shows a graph of the hfe AC
Cobo (almost) equals the capacitance between collector and base (also called miller capacitance). This is a voltage dependent capacitance and increaes with decreasing collector base voltage. Cibo is the emitter base capacitance for the reversed biased BE junction (mostly Veb = 0.5V, or Vbe=-0.5V). This is (...)
Hi, Attached is a waveform of a power MOSFET turn on procedure. * I would like to know why the Cgs ( gate source capacitance) has a constant voltage across it during time interval T2 to T3 ? * Why does Cgs 'not' charge during T2 to T3 ? This is called as a miller plateau region, but the text book explanation is not clear to me. Can someone
Yes, I think you have worked it out before I had time to reply. The miller situation is different to yours. Looking at the miller capacitance idea, the power would be on, the transistor is off and then you try to turn the transistor on (with some resistance in the gate) and the miller capacitance (with (...)
Why it is advisable to share drain of transistor than source of transistor while making finger? what impact it will give ? Less drain-gate capacitance (Cgd) - less miller cap.
Common source has bandwidth reduction due to the miller effect - common drain doesn't suffer from that effect so bandwidth is higher. Keith
Not S21. Maybe you meant S12? Think also the "miller Effect". How the equivalent input capacitance of an inverting amplifier gets whatever little feedback capacitance existing between the input and output terminals amplified by (1+Gain). For an oscillator, there has to be some way a portion of the output gets to wiggle the input gate r
When Vgs reaches the point that makes Vds swing, the miller current (Cgd*dVds/dt) pushes back into the gate and if the drain has a large compliance range, plateaus the gate drive (against its source resistance). So you need a low driving resistance to make it swing fast, or you can add resistance to get a controlled slew. But the nut of it is, Q
Hi All, I have been working on the following architecture for a three stage LDO. 85731 This is a Three stage LDO with a single miller capacitance compensation using inverted current buffers. The first stage is a basic pmos input differential error amplifier. The second stage is like a unity gain buffer. The third s
How to choose load capacitance to prepare test bench for the simulation of 1.8 v saturation design opamp (miller type 2 stage)? If some procedure is there somebody can tell it to me (Even if not the exact value, but the range at least)? How to choose load capacitance such that it won't affect the GBW of design? Thanks in advance, Nishanth
If you relate the question to power rectifiers, larger cap means higher peak current and thus higher Irms/Iavg ratio, in other words lower current rating. Okay. Basically I need a large capacitor in the IC that I design. But I don't it to consume the space in my IC. I thought of using miller Technique to boost the capa
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"
Snubbers can be clamp diodes or small RC spike suppressors like 10Ω + 100pF @ 100MHz. If your driving impedance is lower, then you may need 1Ω 1000pF @ 100MHz. The key is your driving/load impedance and the maximum dv/dvt your triac can handle before it is false triggered by coupling thru the miller capacitance to the gate... and the ra
See "miller Compansation" by using Cascode Structure.
Here's an application note which exactly uses feed forward compensation with no miller capacitance, but that's possibly not what you're thinking of. You might want to describe your application.
Estimating the FM sensitivity is not an easy thing to do unless you have the large signal model of the device. I don't know for sure but it appears the above design of a Colpitts Osc will change freq with the device miller capacitance on the collector. modulating the current in Q1 affects the gain bandwidth product (GBW) and presumably the collect
Circuit will amplify the thermal noise filtered by xtal with fundamental and harmonics and amplify signal to collector tuned fundamental with high gain where phase shift is 180deg with feedback from internal miller capacitance. (CE) THis appears to be series mode osc. Parallel mode might use Xtal in CE feedback path. eg >[URL="talkingelectr
"Negative miller capacitance" aims at reducing the input capacitance.
Series gate resistance or an undersized predriver will give you a slew-rate-limited driver (miller capacitance*dV/dt vs available gate drive). Controlling slew rate internally is better than using a weak driver and counting on load capacitance to limit voltage edge rate, less board level loading variability in timing. You can also segment (...)
Dear iVenky Hi The input capacitance of a transistor , will not change with frequency , it's xc will change by changing the frequency . it's capacitor , with changing at amplitude will change ( one of effects of miller ). Respect Goldsmith
Don't confuse cascade with cascode! Cascode is used to reduce miller capacitance and possibly increase gain and improve bandwidth. Cascade is simply putting one stage after another to increase gain. Keith.
For analog applications, there are two options to speed up an opto-coupler - use it in current source mode, e.g. a cascode circuit or another means that creates a low (AC) load impedance, to overcome miller capacitance. - use it as a photo diode. In this case, you'll need the base terminal. Did you check, if the opto coupler pole is actually
I don't have experience with that kind of amplifier and also see it for the first time and obviously there is some math behind it. But here is what I can say by just looking at the schematic on slide 5 of your attachment. Obviously Cm1 serves as a miller capacitance to create the dominant pole. Cm2 with gm4 create another miller capacitor (...)
One of bad effect is Cgd that have miller effect. It makes loop stability worse.
Dear all, 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)? Thank you.
Hi guys, The op-amp I am working on is used to sense changes in very small capacitance(femtofarads). To get a predefined sensitivity, the input capacitance of the op-amp is limited to 1pF. I tried the usual topologies like two-stage miller op-amp, folded cascode, telescopic cascode etc. For all the cases I am able to reach a noise level (...)
In the CE amplifier the output voltage is in a inverse relation with the Ic current. When Ic increases when the input signal is swinging up the voltage across the collector resistor increases and as such the output voltage decreases (for the basic configuration Vout = Vcc-Ic*Rc). This is not the case for CC and CB. miller capacitance is due to a
With a folded cascode of the first stage and common source as the second stage. How to calculate the slew rate? The value I calculated by Itail/Cc, that is the tail current of the differential divided by compensation capacitance, is far different than the one I simulated. Should we consider the miller effect here? It seems the variance is about
... does HSPICE include all the parasitics that the BSIM4 model takes into account, the intrinsic gate capacitances of the nmos and pmos devices and the miller effect? Actually, all *SPICE simulators are just calculator programs which solve the equations presented in the BSIM suite with the values given from the models. So
There will be some correlation between the poly doping at the gate ox interface, and device VT. You can see poly-depletion effects sometimes if doping is too low or not driven long enough. Drain risetime will respond to gate resistance and miller (Cgd) capacitance. Something like Vgs/Rg=Cdg*dVds/dt. Digital delay embodies half the output ris
I don't know if this will work right, but according to my deduction, it seems like this: Av1 = gm1*ro1; Av2 = gm2*ro2, first pole is about: 1/(ro1*gm2*ro2*Cc) gm1, gm2 is the first and second stage transconductance ro1, ro2 is the first and second stage output resistance Cc is the miller compensation capacitance So GBW is about Av1*Av2*p
miller effect cancellation, or also known as capacitance neutralization is a well known technique. It is well suited in integrated fully differential circuits. In the attachment above, the extra capacitances, cross-coupled between the output and input can be done by connecting MOS transistors with half the size of the input transistors - (...)
In simple terms, the miller effect allows a small capacitance to be "amplified", which is useful for compensation. Using a non-miller capacitance for compensation means it will have a larger value, hence larger area.
FIRST IT IS GATE-source capacitance that you charge up then when you reach VTH, then you charge up the miller capacitance = DG capacitance..... miller is the bigger one that you have to charge up. so its kind of complicated cuzz you first charge up one then the other one.
I wanted how to know how to determine the input capacitance of an inverter. We have many parasitic capacitances like Cgd Cgs etc. Is the ip cap dependent on this. If yes how? N how miller's theorem has to be applied? I got to know that ip cap is just the gate cap calculated from C=εA/d formula. No parasitics and (...)
Thanks for the info. But I think we have to divide the "active clamp" into two categories: One is the gate active clamp to minimize the miller capacitance effect at turn off. The aim of this is to guarantee the OFF phase. Another is the voltage clamp. The aim of this is to limit the over-voltage during switching. I was asking about
Like the attached ,cited from Razavi?s book. 1.The total capacitance at this node A roughly equal to CgS5 + CG56 + CDB5 + 2CGD6 + CDb3 + CGd3, Why 2 * Cgd6 ,is this miller effect. So the Av must to be -1 from Gate6 to drain6. How to get this number? 2.There is two paths from input to the output.The poles of A and N only affect
Hi, All I've designed a buffer for a reference voltage in standard CMOS process. The buffer used a 2-stage miller compensation opamp followed a source follower (the follower feed back to opamp neg), and the output is a follower replica. My problem is that if using MOSFET as the compensation cap, I can save area and big metal wire pathes ( If us
The attached graph is from W. Sansen book, page 189 and I am a bit confused, on one hand, the text in the book seems to suggest that the rule of thumb is that Cc should be smaller than CL, on the other hand, the gm chart seems to in
i have a doubt that whether HSPICE takes care of miller effect during it's AC analysis......this is because capacitances of 2 nodes between which a miller capacitance is connected are not shown by HSPICE of value what they should be after taking miller effect in account. So accordingly does HSPICE (...)
In Gray it is said single stage opamps,such as the telescopic cascode or folded cascode,have only one gain stage;therefore miller compensation is not possible. Why? Can I attach a miller cap between negative input and single ended output?
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?
in wiley sansen book, while he was talking about nested miller compensation , i noticed that he connect Cc between two nodes that the gain is positive , according to miller ; we multiply the cap. by (1-Av) and so , seems like if the gain is positive then -ve capacitance, can anyone tell me what i am missing ?? thanks
the capacitor has negative feedback through it and hence it compensates miller effect and hence avoiding input output coupling so the value of the capacitance should be an approximation of the gate drain capacitance.... Added after 35 seconds: the capacitor has negative feedback through it and hence it comp
Hi, What is miller capacitance? Why it is used in Differential Amplifier?
Hello everybody, I want to design sample and hold circuit using double sampling technique at 160MHz clock (320MS/s) and 70dB IMD. Here I choose the two-stage opamp, the schematics are here. (Two stage module and the double sampling). But slew rate and charge injection decrease the IMD sharply. I try to adjust the miller capacitance, but the effe
the miller effect thrives the input capacitance it a needed one or unwarranted..if it is not needed than how best it can be eliminated,
Search for miller theorem. In brief when a capacitance is connected to the input and the output of a gain stage it can be approximated by equivalent capacitances connected accross the input and the output terminals. These capacitances are given by the miller theorem (is also quite easy to prove).
A is the gain of the system without the miller capacitor.... so all that you have to do to find the value of capacitor to use at the input at that frequency is to remove that miller cap and find the value of gain at that frequency and then use the multiplication factor and place the capacitor....