94 Threads found on edaboard.com: Opamp Suggestion
I am interested in designing a low power low voltage opamp, can anybody give me any suggestion?
Thank in advance.
Analog Circuit Design :: 29.06.2004 07:48 :: piao :: Replies: 1 :: Views: 881
Look they have something. How they call them: opamp evaluation boards I think.
See their application notes which have schematics in them.
Electronic Elementary Questions :: 16.09.2004 15:19 :: djalli :: Replies: 6 :: Views: 2486
Any suggestion on papers or links on designing op-amp for sallen-key filter to be used on baseband. Also papers and links on designing programmable gain amplifiers and limiters for RSSI.
RF, Microwave, Antennas and Optics :: 22.10.2004 01:11 :: ccw27 :: Replies: 0 :: Views: 584
I have completed a 2 stage opamp with GBW of 330MHz, DCgain=60dB, GM=20dB and PM=54 degree. I found that i can't go beyond 3rd order unity gain 200MHz SallenKey LowPassFilter since the o/p signal is out of phase.
Can anyone give any comment/suggestion/solution?
I see 300MHz bandwidth. What opamp did you use?
Analog Circuit Design :: 07.12.2004 16:57 :: djalli :: Replies: 16 :: Views: 2281
I have a circuit like in the attachment. What i want to do is adding 2.5V offset to the input signal. But the rms value of the output is a bit lower than input but there is no clamping on the signal. What may be the problem? My 2.5V reference? or other thing. I use this opamp:
Analog Circuit Design :: 15.08.2005 06:54 :: seyyah :: Replies: 7 :: Views: 1133
How to layout the cascode opamp on RAZAVI'S book ,figure 9.48?
In figure 9.48,
(1) put the M1,M2 ,M1P,M2P in the middle of M9 ,M10 ,M3, M4, M5, M6, M7, M8
(2)put the M1, M2 ,M1P,M2P just in the left or right of M3 to M10
which one will be better?
Analog IC Design and Layout :: 19.09.2005 11:49 :: holddreams :: Replies: 12 :: Views: 1216
find the document ,which my give u come idea hot to characterise the opamp
Analog IC Design and Layout :: 14.07.2006 05:26 :: vijay.kumarreddy :: Replies: 13 :: Views: 1569
Anybody done before & any good suggestion or related documents?
Electromagnetic Design and Simulation :: 25.09.2006 01:49 :: DZC :: Replies: 0 :: Views: 674
I need you guys suggestion.
What kind of circuit need the higher CMRR or PSRR of an opamp?
Plz tell me if you know, thanks!!!
Analog Circuit Design :: 01.02.2007 02:20 :: shaq :: Replies: 5 :: Views: 974
Hwo to bias opamp which is used to force two nodes voltage eaual?
If we use PTAT current generated by bandgap core itself, another loop is created.
The stability is also a problem?
How to bias this opamp?
Analog IC Design and Layout :: 30.05.2007 23:49 :: hebu :: Replies: 7 :: Views: 1888
So I have designed an Op-Amp that has a gain of 80dB and its phase margin is about 45 degrees so it is stable. the problem is that when i hooked it up with a capacitor and resistor to make it operate as an integrator, it always has this small bump at the beginning. When the input voltage is changed at 500ns it also has another bump (please see atta
Analog Circuit Design :: 21.10.2007 23:00 :: firsttimedesigning :: Replies: 3 :: Views: 700
i have to design an opamp in 130nm umc foundry process.This is going to be used in a dual slope adc for the integrator and comparator part .The inputs to this opamp will be biomedical signals like eeg or ecg which have frequencies like from few hertz to 100-200 hz. The supply voltage is 1.2v and i require a opamp with atleast (...)
Analog Circuit Design :: 17.12.2007 05:21 :: hacksgen :: Replies: 4 :: Views: 1830
please find below a small example :
.param voffset=0.1 lot=50%
r1 5 3 100k
r2 5 0 1k
c1 3 0 1p
yopa opamp2 pin : 2 5 3 0 param: p1=1e3 p2=5e8 gain=5000 voff=voffset
vin1 2 0 sin (0 1 100)
.tran 0 7
.plot tran v(2) v(3)
Analog IC Design and Layout :: 16.01.2008 08:45 :: bozzo :: Replies: 1 :: Views: 1052
Does anybody know how to do the AC simulation for fully-differential OTA with sc-cmfb?
This is what I have heard:
1) use vcvs to model the sc-cmfb;
however, what should I put the gain for the vcvs?
A very large value?
Please look at the attachment for the schematic.
2) Use the pac (in spectre)
Thanks a lot.
Analog Circuit Design :: 02.08.2008 04:49 :: tony_taoyh :: Replies: 2 :: Views: 881
In an opamp, I want to increase the bandwidth without increasing the current. I think I should increase the gm of the output transistors whose drain constitutes the high impedance node of the circuit and the dominant pole. I do so but the bandwidth does not increase. What is wrong with the procedure? Any suggestion?
Analog Circuit Design :: 04.11.2008 08:46 :: naalald :: Replies: 5 :: Views: 889
Hi this bandgap the startup circuit works fine untill I apply an offset (vos) to the opamp.
With a positive offset, all it's ok but witha negative one the loop becomes open!
Why does it happen?
Any suggestion to avoid this bad behavior, please?
Analog Circuit Design :: 07.09.2009 08:22 :: crystalballs :: Replies: 1 :: Views: 1426
I'm a new to analog IC design.
anyone can tell me:
what is the basic of about the analog IC design?
before someone told me the opamp is the baisc in analog IC like the CPU in digital IC, is it ture for you??????
Analog IC Design and Layout :: 05.12.2009 06:27 :: zcs20060925 :: Replies: 4 :: Views: 788
Hi I'm designing a telescopic opamp for wimax adc aplication.
Bandwidth : >> 40Mhz
Gain : 50dB
PM : 60 70 degree
I have no problem getting the gain and the PM...but to get the 40MHz bandwidth quite a problem.
All calculation are done user 1st order formula....Can help me with more accurate calculation.
My model use Bs
Analog Circuit Design :: 12.08.2010 01:48 :: harry_croft84 :: Replies: 0 :: Views: 497
If you are worried that the opamp amplifies its input bias current in the resistors then seleect an opamp with Jfet inputs because it has no input bias current.
Analog Circuit Design :: 28.01.2011 13:43 :: Audioguru :: Replies: 8 :: Views: 3862
I ve created a Pspice schematics of a 3 opamp instrumentation amplifier.
I need to plot the CMRR for the there any direct way to plot the same ie CMRR Versus Frequency.?
Analog Circuit Design :: 21.03.2011 09:51 :: themaccabee :: Replies: 4 :: Views: 1441
My question is centered on ADC's of microprocessors connected to sensors via ADC's.
When do we need an opamp?
and Why do we need it, is it a buffer?
let's say I have a PIC or 8051 microcontroller ADC connected to a sensor that needs opamp, what opamps are suitable?
Analog Circuit Design :: 12.05.2011 21:14 :: azaz104 :: Replies: 4 :: Views: 909
Hello, I was wondering if it is feasible to build a 741 opamp out of discrete components. The internal schematic is clear and no double emitter transistors used.
What I need is a suggestion for the transistors that could be used.
(this will be used in a sweep circuit)
Analog IC Design and Layout :: 10.06.2011 10:58 :: neazoi :: Replies: 5 :: Views: 1352
The gain of an OP-amp is very high so can be set to any reasonable value with external components, so ANY op-amp would do. If you are after some very special parameters such as low noise, very low drift, high frequency response funny DC supplies, then a specific device would need to be bought. I like these for general purpose :- [url=www.map
Analog Circuit Design :: 25.08.2011 15:40 :: chuckey :: Replies: 4 :: Views: 1152
What is the high level of step impulse for testing slew rate of an opamp? Unity gain topology, supply 1.8V. May I put step from 0V to 1.8V with rise edge of 1ps, or there is some way to exactly calculate levels?
Analog IC Design and Layout :: 04.04.2012 09:25 :: Spliter :: Replies: 3 :: Views: 1015
I want to calculate the gain
In your circuit, gain=1 , due to full negative feedback.
If you want to measure gain & phase vs. frequency, use your opamp in open loop configuration.
There are a lot of threads about this in the forum. E.g. search for "Middlebrook" .
Analog IC Design and Layout :: 23.05.2012 13:41 :: erikl :: Replies: 11 :: Views: 745
Anytime I read something like the header "opamp behaves strangely" I first look at the power supply - and very often single supply is used without knowing the consequences (proper biasing).
Analog Circuit Design :: 21.10.2012 10:10 :: LvW :: Replies: 11 :: Views: 359
I have a three-stage LDO.
The simulation result is in attached (without compensation).
Looks like the dominant pole is only about 19 Hz, the second pole is around 90 kHz. UGB freq = 640 kHz.
The dominant pole is too low. And the DC gain is too high.
I tried to do a miller compensation. It turns out the dominant pole moves t
Analog IC Design and Layout :: 05.12.2012 02:33 :: wandola :: Replies: 4 :: Views: 378
I will check the dac and opamps today.
In my little project user will use always these 9 switches like that first switch group will push the user to select one of these 3D, 4D, 5D
second switch group will push the user to select one of these 8Kv- 14Kv- 16Kv and so on totally there will be 9 switch and operator will use these switches to
Hobby Circuits and Small Projects Problems :: 05.02.2003 12:42 :: VolkanG :: Replies: 3 :: Views: 1515
What things should be considered when design audio codec
with sigma delta ADC ?
What is the requirement of the opamp for example ?
Analog Circuit Design :: 30.07.2004 05:19 :: Vitamin-C :: Replies: 12 :: Views: 1871
thanks for ur reply.
i'm using hspice and i still don get from ur answer that how can i actually configure the opamp in order to ge the CMRR vs Freq?
hmm...maybe u can show me in netlist or a diagram.
thanks in advance.
Analog Circuit Design :: 04.12.2004 23:15 :: always@smart :: Replies: 8 :: Views: 2514
If the accuracy is not extremely critical, you can divide down a reference of your choice and buffer it with an opamp. You will have to adjust the circuit yourself, so the accuracy can only be as good as your meter, reference, etc.
I hope the current requirement is not high.
Analog Circuit Design :: 24.01.2005 12:49 :: VVV :: Replies: 2 :: Views: 689
There is no such a thing like "minimum input voltage". opamps are linear devices and will amplify any input voltage.
However, because of temperature drifts, bla, bla ,bla .. with opamps like 741 one should avoid using them with voltages below "certain" level. I wouldn't use 741 for amplifying signals below,say, 1mV. Try to employ more contemporary
Hobby Circuits and Small Projects Problems :: 17.03.2005 04:48 :: IanP :: Replies: 3 :: Views: 5786
What a lot of people do when they need a single ended to differential swing is that, they use another opamp with gain =-1 in addition to your main amp. This would generate an equal and opposite swing.
Analog Circuit Design :: 15.04.2005 03:22 :: Vamsi Mocherla :: Replies: 3 :: Views: 601
i want to get a negative supply from a positive.below circuit fails when i connect the output to an opamp.why could it be? anyone having an opinion, a suggestion? thanx...
Analog Circuit Design :: 08.05.2005 12:29 :: nomad :: Replies: 1 :: Views: 1015
i am designing a S/H circuit.which is used in the 14-bit pipeline ADC.the main parameter : the AMP dc gain=104db, GBW=160MHz. sampling capacitor=13p.
and the S/H's load=14p.the S/H circuit's architecture is flip-around（the architecture is referenced in this paper:A 3-v 340-mw 14-b 75-Msaple/s CMOS ADC with 85-db SFDR at Nyquist input).but n
Analog Circuit Design :: 14.07.2005 00:13 :: winsonpku :: Replies: 8 :: Views: 1204
For basic design understanding, can refer to:
Analog IC design - Johns/Martin
To further more on opamp, can refer to:
Introduction to CMOS OP-AMPs and comparators - Roubik Gregorian
Analog IC Design and Layout :: 27.07.2005 02:16 :: richloo :: Replies: 13 :: Views: 3403
For the SC gain stage(*2) in pipeline ADC,I used ideal switch and ideal opamp.But if input is 1v peak sin wave, the SNR of output is just 60dB.But if input sin wave is 0.5V, the ouput is above 90dB. Is that correct?I used this SC gain stage in pipeline stage,I can't get expected SNR.But I can't increase SNR for this circuit.Anyone can give me sugg
RF, Microwave, Antennas and Optics :: 06.10.2005 03:20 :: tyd :: Replies: 0 :: Views: 517
hi, im aware of simulating inductor using opamp. do capacitors can be done same way?
Try simulation using an external series resistor and inductance (see attachment).
I have not tried this out (this is just a suggestion).
Analog Circuit Design :: 12.01.2006 03:29 :: dunn :: Replies: 2 :: Views: 947
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 02:45 :: sixth :: Replies: 5 :: Views: 2319
Can anyone please give some suggestion on what type of opamp is suitable to be build following these specifications:
1) VCC=3 to 5V
2) Rail to rail input and output stage. D-range is about VCC-0.4V for input and output.
3) THD < 0.1% for 20Hz, 1kHZ and 25kHz.
4.) GBW > 1MHz
5.) Open loop gain , 50~80dB
Analog Circuit Design :: 05.03.2006 00:18 :: chihwt2003 :: Replies: 9 :: Views: 952
well, that's really helpfull
but unfortunately my application need the stability measurement, since i want to measure a 1uV change in the input from 10 ton load cell.
I'm using Sigma delta ltc2440 now and it's quite unstabil, and i look at the same circuit that can handle the sensor. It only uses dual slope adc with 2 opamp and 1 cmos multiplexer
Microcontrollers :: 10.05.2006 06:31 :: ex4 :: Replies: 4 :: Views: 2960
why you need that opamp with such spec?
if no high gain, it means that it should have very high bandwidth?
i think it is very hard to design such a opamp with 0.18 tech.
Analog Circuit Design :: 20.07.2006 11:25 :: tuza2000 :: Replies: 4 :: Views: 1390
I am designing a 10bit pipeline ADC. The schematic simulation shows that the odd harmonics are too large(especially,the third harmonic is 55dB).
Can anybody give me some suggestion on how to find the reason?
opamp (settling time)
reference (settling time)
Analog Circuit Design :: 20.09.2006 04:27 :: wdd :: Replies: 8 :: Views: 1432
Depending on how your integrator is build up! I suggest it is built with an opamp. Then simple short with a switch between the cap instead of the output.
Analog Circuit Design :: 10.05.2007 11:29 :: rfsystem :: Replies: 7 :: Views: 3185
I'm desigining an high gain opamp for a application in a feedback loop like in common mode feedback circuit. Since, this opamp is in the feedback loop, which is a low frequency application, my question is what is the value in dB I should design for both the CMRR and PSRR of this opamp. Is it the PSRR need to be at least 50dB at (...)
Analog Circuit Design :: 08.07.2007 22:49 :: suria3 :: Replies: 1 :: Views: 794
the opamp in the bandgap circuit just fixes two voltages the same , it will have little effect on the TC of output voltage.
so, I think the large TC comes from your res ratio, it is no well setted. the ratio of the res have large effect of TC.
Analog Circuit Design :: 12.07.2007 22:05 :: iamxo :: Replies: 11 :: Views: 995
I have some problem on high speed buffer design, in which a big cap is used to get a low impedance at high frequency. what bother me is that there is a drift in transient simulation from DC value of reference output. I try to minimize the output impedance of opamp to reduce the drift,but there is still some difference between dynami
Analog IC Design and Layout :: 30.10.2007 02:34 :: lotoy :: Replies: 1 :: Views: 628
My suggestion is to use PWM technique, are you familiar with some kind of a micro controller, or you want a design with simple analog components like opamp, comparator?
The pwm modulator frequency should be about 20kHz, the output will have a LC filter to filter the carrier (20Khz) frequency out.
Professional Hardware and Electronics Design :: 01.11.2007 17:01 :: LaszloF :: Replies: 4 :: Views: 3110
are you obliged to use the pic?
no,but i cnt use opamp because i can't use -ve input voltage...u got other suggestion?
Added after 2 minutes:
Dear Desertkids, well to use PIC for to conversion of analog signals, you'll have to use a PIC with the capability of
Microcontrollers :: 18.12.2007 19:57 :: desertkids :: Replies: 6 :: Views: 1148
I also need to measure slew rate, output swing, cmrr, psrr, offset of opamp in Mentor Graphics. Can u give me any suggestion?
Analog Circuit Design :: 06.12.2010 04:05 :: univer_solar :: Replies: 3 :: Views: 753