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Slew Rate In Op Amp

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105 Threads found on Slew Rate In Op Amp
Hi, Does anyone know how to work out the CMRR (Common Mode Rejection Ratio), PSRR (Power Supply Rejection Ratio) and slew rate using Cadence simulator for a 741 Op-amp? Could anyone explain to me how to work out the differential gain of my op-amp using the Cadence calculator? Thankyou.
read this short pdf. u could get some idea... it depends on the compensating capacitor
Does anyone know how to alleviate the effect of slew rate in a single ended telescopic op amp(please see )? So far i know i can use coupling transistors but i am not sure where to put them.
what is your slew rate target. 2000V/us?
Hi Guys, I like to know, how do we measure slew rate of an opamp in cadence. What is the relation of slew rate and settling time. Thanks
is there any possibility of improving slew rate of a op-amp IC 741
Define slew rate in mathematic term.
I have designed a fully differential op amp. I do not know exactly how to measure the slew rate for a fully differential op amp. Generally for a single ended op amp we connect the op amp in non inverting(feed back) mode and measure the slew rate. How to (...)
Hi, i've designed a CMOS folded cascode opamp to have a slew rate of 150 V/us (Iss of the differential pair is 30 uA and CL = 200 fF) in unity gain configuration. I found that ICL is about 1 mA.I saw current in the differential pair is unbalanced in one branch only for a very quick time so the capacitor can't charge like i would. So i (...)
Unity gain configuration allows for large input step (max). slew limited part ends when the feedback takes control of the loop, so it is easy to see that the unity gain configuration would exhibit the same slew rate over a larger time/voltage that makes it easier to demonstrate and measure. The series resistor would (...)
Hi Godfreyl, I am interested in CMOS chip design. And better matching for offset, PSRR, CMRR, slew rate symmetry, EMC etc.
Hi All, Does anyone has idea in adjustable slew rate circuit. I need a circuit that can adjust slew rate of rising and falling edge separately. And the adjustable rate from 1ns to 100ns in 0.5 or 1ns per step. Does anyone has idea in this? Thank you in advance! Wenye
The slew rate is not always defined by the output node. It is sometimes defined by the internal node, for example, the output node of the first stage in a two-stage amplifier.
Hi everyone I know that traditionally, an op-amp connected as a comparator consistently underperformed dedicated comparators in most respects. But that was when we were comparing a 741 and a 311. Op-amp technology has progressed faster than comparator technology. We have today op-amps with exceptional speed, which I would expect to (...)
for slew rate ,plz refer
Tht's right - if you need fast response it is impossible to slew the gate of the pass device up and down with 100nA. This is probably a device that changes it's bias if it is in slew - similar to the "gain boosted" or "slew-rate enhanced" op amp. So we cheat, and slew the gate with 2mA, (...)
Steps u can follow to design an amplifier: 1) Decide with the architecture of the opamp which meets your specifications. Like Single stage opamp, two stage, Folded cascode etc. 2) Determine the type of compensation needed for your specifications. This depends on how many stages your opamp has. 3) Hand calculate the (...)
dc gain, phase margin, power, input/output common range, cmrr, pmrr, slew rate,etc, I do this simulation and tran simulation
sreejith, The important thing to remember is that gain-bandwidth product is a small signal parameter, while slew rate is amplitude dependent. For example, the slew rate of a sine wave with a 10V peak is 10 times the slew rate of a sine wave of the same (...)
The current of the first stage should be smaller because you would get higher gain(higher mos output resístance ro). However, it should be not too small because of slew rate. The current of the secound stage should be higher because of easier Miller compensation (gm is higher, Cm smaler), and higher output current .
Hi In fact, specification of an Analog filter depends on application requirement. that is, if your filter does not have a large signal at its input, slew rate of the Opamp or OTA is not very critical spec. that is in most cases. to design Gm-C filters you can refer to John & Martin's book, Chap. 15. another good tutorial paper about (...)
from what u say i think u r dealing with noise and slew rate problem..... noise is hard to reject because it is omnipresent.... The slew rate problem is where the input changes faster than what the op-amp can support..... so try changing the op-amp....
how to understand the slew rate of full differential folded cascode op amp?SR=Iss/CL or
such as cmrr psrr slew-rate settling-time and so on. can anyone provide the simulating schematic? or some reference? thanks
hi friends and fellow professionals, Thanks for viewing my op amp specification. I will update my op amps' other specs such as voltage swing, settling time and slew rate. Thanks again to analog_prodigy and sadigh for your comments. My op amp doesnt have any specific application. I am concentrating on (...)
i find your question very general with no specification of the modulation technique or the opamp number etc... opamp only has slew rate and that is the maximum rate of change of output possible with the particular opamp and it varies from opamp to opamp.....
Hi, can somebody please tell me, the precedure of measuring slew rate of a diff op amp in cadence?
Hello Can someone please explain the impact of load capacitor on the slew rate of a standard two stage op-amp? In addition, can the use of cascoded miller compensation improve the slewrate performance of an op-amp? I will appreciate if someone can point out the method to derive the (...)
Hi, Can any one tell me How to increase or decrease slew rate of an op amp.
The circuit itself without the resistor is not stable. Suppose presently there is a voltage of Vin = 1V atthe non-inverting input of the OPamp. Then at the steady state the output voltage across the capacitor will b 1V. Now the input voltage changes to 1.2V. It has to chaarge the capacitor to 1.2 through the large input resistance of the OPamp. The
Hi, I just finished the study in op-amps design from Razavi's book. However, I feel not enough in some topics like CMFB, slew rate and some other practical issues. Could you recommend me any other books like Allen or Meyer so that I can study further? Thanks a lot! Wang
I understand that when a large step input is applied to the op amp this causes slewing because the diff amp's input transistors are in cut off/triode. As you can see that the output after slewing starts to ripple. During this rippling the transistors are in saturation and the error voltage Ve is decreasing due to (...)
I need the theory of calculating the gain in the small signal modelling for differential amp and output stage and the calculation on slew rate.
Hi all~ I am constructing an IC tester for op-amp now, which require to test most of the fundamental parameter of op-amp and need to make sure that, if the op-amp pass my test, then it should be working fine. So I construct a simple circuit to test for it's parameter. Currently I can only able to test Input offset voltage, Input offset (...)
A simple op amp buffer is a voltage follower. (look it up) Connect the output to the inverting input, feed the signal to the non-inverting input. You will need a resistor to ground on the non-inverting input for bias. Op-amps are not that fast! Better check the output signal with a scope to make sure you are not getting slew (...)
Hi, I did an lab exercise and had a result of slew rate around 0.75V/us. Wanted to recreate the exercise at home and build the same circuit - an astable multivibrator with feedback resistor of 20kOhm, 100nF cap connected to negative input. 10kOhm resistor at the output going to the positive input and from that another 10kOhm resistor going to the
Hi In my opinion, you should start from the gain spec. Your gain is >=70db. let say gain is 80db = 10000 Gain = Gain1* Gain2 Gain1= gm2*Rout1,2 = gm2*ro1*ro2/(ro1 + ro2) = gm2/Id2 * Gain2= gm6*Rout6,7 = gm6/Id6 * VA = Leff* 1/lambda (Leff = Ldrwn - 2Ld) choose Ldrwn =1um ---> Leff = 1 - 2*0.25
If you cannot get the LM324 to work above 2kHz you are doing something wrong! Their bandwidth is around 1MHz, as far as I recall. Keith The LM324 is the first low power opamp. Low power means low performance. At 1MHz and with a high supply voltage its voltage gain is 1 like a piece of wire. At lower supply voltages i
A crossover frequency in a speaker system is the frequency where the woofer's output is reduced and the tweeter's output is increased. An opamp has frequency compensation so that it does not oscillate when negative feedback is applied. The frequency compensation causes the gain to decrease starting at a very low frequency and the gain drops at 6
Actually, the maximum operating frequency for an op amp is given in the datasheet, but it has a different name. Look for gain bandwidth product or GBP on your datasheet. Sometimes there will be a graph showing open loop gain versus frequency. Since there is a rise time or slew rate for signals in an op amp, there is an (...)
Yes, you can obtain Vout max, min with DC sweep. But you can't have slew rate. It needs transient analysis.
Hi sgugan, 1) CA3130 - 10V/us slew rate , 15MHz bandwidth. 2) TL081 - 13V/us slew rate, 3MHz bandwidth , cheaper and easily available compared to CA3130.
In my opinion, the datasheet gives all necessary information. You would want to apply feedforward compensation for optimal phase margin and highest gain at high frequencies. According to the bode diagram, you can expect about 10 dB at 10 MHz. You should consider that the achievable large signal amplitude is very limited due to slew rate (...)
i need an example of slew rate which contain op-amp and with explanation, i have seen some examples but i dont understood ,thank you
In fact, it depends on your application. Generally, opamp spec are: input range, output range, min supply voltage, current consumption, slew rate, noise, offset, gain, phase margin, bandwidth, PSRR, CMRR.
If you are designing for a real design, you get the parameters from your foundry. If it's a circuit design exercise, ask your supervisor or tutor. There are some typical design parameters available on the internet, that are often used for academic purposes. E.g. these
If an opamp has a slew rate of 0.8V/microsecond, the gain of opamp is 4, and at t = 0, Vin = 1V, and takes 5 microsecond to constantly increase to 2V. Will Vo take (4*2)/0.8 * 5 = 50microS to constantly increase from 4V to 8V at t=0? thanks in advance
If the LM358 model includes GBP and slew rate, there should be an effect. You'll get the strongest bandwidth effect at low input voltages.
Hi all: How to perform a slew rate controlled NMOS load switch? I try to find it in papers, but none talks about that.
Thanks for the references it helped . The op amp selected has unlimited capacitive loading and also it gives a good output for a limited range . I am trying to give a 100mV -Vac at 20kHz . the slew rate for the op amp is 125V/us. So at 20kHz i am able to give only around 19mV as input. So any suggestions for this.