50 Threads found on edaboard.com: Opamp Power Dissipation
I would need some help in a power dissipation issue.
I have a power opamp that works in a non-inverting topology.
Here some data:
- Single Supply = 12V
- Output voltage = 6+3*sin(wt) V
- Output current = 100*sin(wt + alfa) mA
w = angular frequency
t = time
alfa = angle between current and (...)
Analog Circuit Design :: 04.10.2009 02:49 :: berni80 :: Replies: 1 :: Views: 790
Put a zero-volt voltage source in series with all the op-amp stages and then measure the currents through them.
This will give you power per stage - by V*I (of course) and is more useful, than just finding the total power for the opamp.
Analog IC Design and Layout :: 27.05.2005 17:11 :: uncle_urfi :: Replies: 3 :: Views: 881
It all depend on the specification that you are looking for. Most of the time the process we use to design a opamp will be the crucial point as it will limit the design parameters and the rest as others mentioned in the post.
Analog Circuit Design :: 23.04.2007 10:02 :: suria3 :: Replies: 8 :: Views: 1843
Due the application of dc feedback, I think a typical differential stage opamp would serve the purpose. If the frequency of application is high, a cascode stage differential opamp would serve the purpose
Analog Circuit Design :: 23.11.2004 02:30 :: hrkhari :: Replies: 12 :: Views: 2357
I need a opamp with DC gain>80dB and Unity Gain frequency >100MHz. At first I try to design it with the class-A two-stage structure. but it is difficult to satifiy both the DC gain and phase margin.
Who can give me some advice about how to design. such as, if class-A structure can meet the request, or which kind of structure is more suitable. and
Analog Circuit Design :: 03.02.2005 07:32 :: lilac :: Replies: 8 :: Views: 2974
u r not designing an opamp, it's a wideband amp.
if inductors r allowed, it would be easy.
Analog Circuit Design :: 20.03.2007 21:32 :: obovolo :: Replies: 3 :: Views: 1029
is it good to use folded cascode opamp for the bandgap? bcoz it have more pair to match and more prone to mismatch and introduce input offset.
Analog Circuit Design :: 10.08.2007 21:55 :: surianova :: Replies: 2 :: Views: 919
In a conventional two stage opamp operating in weak inversion for ultra low power dissipation, does all transistors operate in weak inversion OR only differential pair transistor and tail transistor operate in weak inversion.
Plz, Need help!
Analog Circuit Design :: 25.01.2008 01:34 :: amitjagtap :: Replies: 7 :: Views: 2819
I am using a fully differential opamp (THS4131) for driving a 24 bit differential input analog to digital converter(AD7766). But there are many problems in my design , the drift voltage between two outputs of THS4131 is not a constant value and will increase by elapsed time. after 2000 seconds the drift voltage will increase to 610uV that is 10bit
Analog Circuit Design :: 11.03.2009 03:06 :: Mehdi1357 :: Replies: 0 :: Views: 849
Suppose I am using an opamp as an amplifier with +12V as pos and _12 as neg supply. Consider supply current as 3mA at no load.How will i calculate the power dissipation. Next is the opamp configuration as precision rectifier with same supply and current. Will there be any change in power (...)
Analog Circuit Design :: 07.07.2010 08:26 :: akhilmukund :: Replies: 3 :: Views: 1965
In my design I am using an LM321 opamp for outputting max 24V with a current of 22mA. The LM321 is protected against short-circuits but only when not exceeding the maximum power dissipation. Is there a way protect the opamp against exceeding the maximum power dissipation when (...)
Analog Circuit Design :: 02.08.2009 17:08 :: Wamor :: Replies: 2 :: Views: 2190
I'm builiding an amplifier circuit using resistors and opamp(LM741). I already got everything about it, but I'm also asked to waste as little power as possible. Is there any solution for this. It seems like a very stupid question. I'm new to designing analog circuit.
Thanks in advance for any help.
Analog Circuit Design :: 09.03.2010 06:47 :: mmnr00 :: Replies: 6 :: Views: 514
what should we really consider in designing opamp in BGR?
Analog Circuit Design :: 10.06.2010 21:05 :: aifi :: Replies: 6 :: Views: 1702
when designing the op in bandgap reference, how large the load capacitance should we consider? (generally)
i have designed a two-stage opamp with following specs that meant to be used as an error amplifier in a buck converter:
DC Gain: 78db
Phase Margin: 85 degrees
compensation capacitor: 3
Analog IC Design and Layout :: 01.08.2010 09:07 :: bluemotion :: Replies: 3 :: Views: 652
Hello to all
I am new in this froum ! i have the course Analog integrated Cmos design (razavi book is the ref.) semester but i dont know what to do. i have a Desgin problem and i dont know were to begin or what to do ! please take a look to my project and help me in design . if you have any link that have design like this so i could find the way
Analog Circuit Design :: 01.02.2011 12:13 :: tavoosi :: Replies: 3 :: Views: 550
you're right, but I have not the complete knowledge of opamp circuits, and I have a very little time to make this circuit works (I know it's not the correct way to do these kind of works..)
I have thinked that maybe there was a problem of impedance matching from the output of the first stage and the input of the second. So, looking in the output
Analog Circuit Design :: 04.05.2011 05:13 :: vaka85 :: Replies: 20 :: Views: 2483
To achieve the highest gain bandwidth, which one is more reasonable, multistage(3 stage) or gain boosting with 2 stage?
Analog IC Design and Layout :: 12.07.2011 03:46 :: zeldazzz :: Replies: 3 :: Views: 490
I am considering this circuit design for a low-cost voltage regulator:
The load resistance (R4) is expected to be about 2.5 ohms. I am considering 2N3055 since I have them on hand and they seem to be a suitable fit with regards to their power han
Electronic Elementary Questions :: 22.08.2011 00:38 :: cgchas :: Replies: 1 :: Views: 682
If you take fast opamp and slow it down you will get what you need - like Video opamp.
The OPA355 = 0.02% IN ≈50ns
Analog Circuit Design :: 12.12.2004 04:34 :: moda :: Replies: 7 :: Views: 759
the gain is moderate so you can do this design with 2 stage opamp. Use Nulling resistor to do compensation using transistor in triode mode. If you want step by step example, go to and look at P Ellen's lecture notes. This project is very do-able and won't take you long to design. Layout is another game, it comes with practice. G
Analog Circuit Design :: 11.01.2005 17:51 :: chinito :: Replies: 11 :: Views: 1464
I have designed an two stage opamp with following performance
open loop gain: 87.1dB
unity gain frequency :35.3MHz
Phase Margin: 64
Is there any other test i have missed?
By the way, the slew rate is quite low, how can i improved it?
Analog Circuit Design :: 21.01.2005 22:05 :: sisching :: Replies: 3 :: Views: 1430
How can I convert 50Hz AC to a square wave so that I can feed it to a microcontroller? Will CD4093 work here? I will steps down the ac to 5volts then use a diode in series before hooking it to CD4093?
1) Use a step down transformer to step it down to say 5V AC at 50Hz.
2) Then use a 741 op-amp fr
Microcontrollers :: 24.03.2005 17:07 :: v_naren :: Replies: 8 :: Views: 4964
For 1, I think we should also consider the power dissipation or other spec. I prefer biquad since you implemented filter in sc filter.
For 2, I think discrete time domain will give you similar result with continous time domain, and the accurate response maybe need to be verified in transient .
For 3,4 . I think it depends on ur opamp (...)
Analog IC Design and Layout :: 11.07.2005 10:45 :: ablue :: Replies: 9 :: Views: 1012
1V supply opamp is not difficult. The point is what kind of specification is required. For example, input common mode range, output range, output loading, bandwidth and application.
Analog Circuit Design :: 01.08.2005 09:12 :: kwkam :: Replies: 6 :: Views: 752
I think for real low noise performance. say 2uV (20-30kHz), maybe opamp shouldn'd be used.
Analog Circuit Design :: 13.02.2006 17:54 :: vonleo :: Replies: 3 :: Views: 850
If CMFB is not present, the common mode gain will increase and deviates the basic idea of DIfferential opamp. So inorder to control the common mode gain,we introduce as Voltage controlled voltage source circuit. This will maintain a constant DC level at the output. This value is actually half way between VDD and VSS. Common mode feedback will have
Analog Circuit Design :: 06.02.2006 23:55 :: avlsi :: Replies: 2 :: Views: 859
"PMOS body connected to drain..."
why not connected to power or source?
can anybody share to me a CMOS opamp net list roughly meeting the following specifications.
DC gain >75dB
Unity-gain frequency > 150MHz
Phase margin at unity-gain frequency > 65o
Slew rate > 50V/μsec
PMOS body connected to drain and
Analog Circuit Design :: 08.04.2006 05:26 :: swicap :: Replies: 4 :: Views: 3219
If you need a 20mA clean current source, why not build it with and opamp?
Why do you need the switching regulator?
Perhaps I do not fully understand the application. Can you be more specific?
A good source of info for switching regulators are the websites of TI, National, Linear Tech, Maxim.
Analog Circuit Design :: 29.05.2006 12:22 :: VVV :: Replies: 3 :: Views: 712
Hello guys ,
I'm student in swiss federal institute of technology in Zurich . I'm very grad tojoinin this forum with all of you .
In this semester, I have a semester thesis : design a high speed sample and hold (SH) circuit. I use T 0.13um CMOS technology ...
For the OTA, that is used in SH circuit, I have tested all topology telesopic cascod
Analog IC Design and Layout :: 22.11.2006 15:32 :: aic_zh :: Replies: 5 :: Views: 1261
For me it look like switching time (rising and falling) problem and driving two MOSFETS of one general purpose opamp is rather NOT good engineering achievment ..
One option to slove this problem is to put drivers between opamp's output and MOSFETs' gates - separate for each MOSFET ..
BTW: Do you need this opamp at all???
You can (...)
Electronic Elementary Questions :: 05.03.2007 00:20 :: IanP :: Replies: 3 :: Views: 630
The gain, BW and o/p swing u refer is for opamp or integrator??
You need to know the specifications such as the power supply voltage rail, power dissipation for determine the opamp structure. :D
Analog Circuit Design :: 07.06.2007 01:37 :: YingChow :: Replies: 3 :: Views: 2288
ok i agree on that..... but what about the power dissipation, GBW, offset voltage etc etc..... actually what are you designing this opamp for.....
Analog IC Design and Layout :: 23.07.2007 02:58 :: A.Anand Srinivasan :: Replies: 8 :: Views: 756
compared to inverting amp both common source and common emitter are cheaper solutions but they suffer from nonlinearity due to channel width modulation and early effect... inverting amp using opamp doesn't suffer from nonlinearity but the power dissipation is more....
Analog Circuit Design :: 25.08.2007 12:22 :: A.Anand Srinivasan :: Replies: 19 :: Views: 1525
what opamp are u using.... the MOSFET doesnt need current drive to drive it... my guess is that the inverters are used for speed opamps are generally slow compared to inverters....
Analog Circuit Design :: 10.11.2007 21:23 :: A.Anand Srinivasan :: Replies: 8 :: Views: 656
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
Analog Circuit Design :: 16.12.2007 18:18 :: hbsustc :: Replies: 0 :: Views: 753
There is short circuit in your schematics on high frequency between OutA of U1 and OutB of U2 through C7. OutA of U1 would not do anything to InB of U2 in your circuit.
This would probably not explain 300mA extra current (80mA is normal excluding loads)
Unused amp should have inverting input connected to output and noninverting input conn
Analog Circuit Design :: 20.10.2008 18:18 :: Siniąa :: Replies: 12 :: Views: 1056
I need to design an output stage (third stage) for a two-stage compensated opamp. I have gone through some related papers and text. After reading them, I have built-up some interpretations:
1. The main design specifications whilst designing the o/p stage are a) output swing, b) power dissipation (or efficiency), c) linearity (or
Analog Circuit Design :: 24.05.2010 08:17 :: samiran_dam :: Replies: 0 :: Views: 424
If you intend to calculate the W/L values that will make your circuit work as you want, forget it. That's just impossible because you lack the exact equations and the math would be extremely difficult.
If your designing an high speed opamp your transistor sizes should be as small as possible to keep a good bandwidth. Besides that, PMOS should al
Analog Circuit Design :: 15.06.2010 08:10 :: fcfusion :: Replies: 1 :: Views: 630
I have a 6v 1.3A battery and I want an opamp that works with it. I want the opamp tp draw as much current as it can from the battery.
My question is, which part of an opamp datasheet should i be looking at in order to meet my needs. I think i understand the the voltage part but i don't understand how you can tell how much current will be (...)
Electronic Elementary Questions :: 12.01.2011 21:09 :: kavkav :: Replies: 15 :: Views: 486
I suggest you use several stage of opamp to get 65dB at 500MHz
Analog Circuit Design :: 22.01.2011 08:25 :: kwkam :: Replies: 3 :: Views: 364
I = 1,4A
R = 0,1R
P = (0,1R)*(1,4A)^2 = 0,19 ~1/5W
V = (0,1R)*(1,4A) = 0,14V
Use an opamp to multiply that voltage to full-range magnitude of A/D :
K = 5 / 0,14 ~ 35
K = 3,3 / 0,14 ~ 23
Hope this help
---------- Post added at 10:45 ---------- Previous post w
Microcontrollers :: 21.04.2011 05:45 :: andre_teprom :: Replies: 4 :: Views: 1171
Hi, I want to design a circuit which can detect current pulses and give static voltage in accordance with
current passed. For example if a current pulse of 10ms duration passes through my circuit than I want my circuit to give voltage and hold it there. I have tried using sense circuits for dc power supply in which a
sense resistor senses curre
Analog Circuit Design :: 16.07.2011 05:40 :: pona :: Replies: 2 :: Views: 308
Current delivered from op-amp output to load depends on voltage at the output, load resistance Rl, output resistance Ro and your series resistance Rs. Current through load can be determined from Ohm's law. In that case Io=Uo/(Rs+Ro+Rl). Considering that Ro is internal resistance of opamp which is integrated circuit, you cannot chamge it. So the onl
Analog Circuit Design :: 25.09.2011 15:44 :: poorchava :: Replies: 4 :: Views: 417
input voltage is 25 v,R sens is 0.1ohm (Rshunt) and the current i have measure is 3.5A.
1. Can you please help in finding the value for resistors.
If 25V is also the supply voltage for the opamp, use Ra=Rb=Rc=Rd = 1..10kΩ , R1=R2=100kΩ , and R3=R4 depending on your required gain = R3/R1 = R4/R2 . Thei
Analog Circuit Design :: 26.09.2011 12:52 :: erikl :: Replies: 9 :: Views: 402
I have to design a CMOS opamp at 135 nm Technology.........
I have the circuit diagrams and parameters at 180 nm . I have to simulate it on TANNER EDA.
I have model file for 135nm :
* MOSIS WAFER ACCEPTANCE TESTS
Analog IC Design and Layout :: 17.01.2012 04:46 :: Karandeep :: Replies: 17 :: Views: 1206
A couple more thoughts.....
I would use a 1 Ohm resistor instead of 5 Ohms for the current sensing, to reduce the voltage loss and power dissipation.
IIRC, a 741's inputs can't go all the way down to the negative supply rail, so it's probably a good idea to use a different opamp, or change the biasing.
Power Electronics :: 21.06.2012 22:27 :: godfreyl :: Replies: 5 :: Views: 675
1. Connect resistor between sensor resistor (200 Om) and opamp input .
2. Input Op Amp must be pulled to Vcc and GND through Fast/Schottky diodes (in reverse bias). It restricts input voltage level on the range -0.7V and VCC+0.7V
Analog Circuit Design :: 02.01.2013 18:43 :: KonstanU :: Replies: 16 :: Views: 508
The maximum supply current is 4.5mA per opamp. There are two opamps. The total supply is 30V.
Then the dissipation with no load is 4.5mA x 30V x 2= 0.27W.
The thermal resistance of the tiny surface-mount case is 190 degrees C per W so if the ambient is 30 degrees then the chip is at 81.3 degrees C which is warm but not too hot. A load makes (...)
Analog Circuit Design :: 28.02.2013 19:07 :: Audioguru :: Replies: 28 :: Views: 1564
folded opamp has larger silicon consumption
Analog Circuit Design :: 26.04.2007 12:57 :: waxtomato :: Replies: 6 :: Views: 6253
... It should deliver as much power as possible to a 20 ohm load. Therefore, I am trying to make the output impedance as near to 20 ohm as possible.
No, to achieve this, Rout ≪ 20Ω !
Thus, obviously I should use a common drain MOSFET. However, the problem is output impedance of a common drain mos
Analog Circuit Design :: 14.02.2010 07:31 :: erikl :: Replies: 7 :: Views: 2693