Re: Need help to design a transimpedance amplifier

#90216

This is the article from Burr-Brown that my excel file simulation is based on. If you have problem understanding what I wrote, read this article:

Understanding this, you can then find the relevant numbers from the datasheet and plug into my simulation file and see the total noise.

Re: Need help to design a transimpedance amplifier

#90215

try use the excel simulation file I uploaded a while back and enter in the numbers of your other opamps from the datasheet. If you read through the explanations, they will show you how to enter the numbers into the ones in red color. You can find the numbers from the datasheet. Then you adjust the feedback capacitor Cf+Crf on line 31 to get the 1MHz BW and look at line 47 to 51 for frequency response and inband noise. The total noise is the rms noise. If you shield the circuit properly, you should see the result similar to the number. Remember this is rms noise.

Re: Need help to design a transimpedance amplifier

[email protected]

#90214

Hello All,
Thanks for your response...
Well I have tested almost all inputs in LTSpice as per my design criteria:...it works fine on the screen...

Parameter	Goal
Gain	900 kV / A
V_{out min} (at? 112 nA)	100 mV
V_{out max} (at 5 A)	4.5Vp-p
-3dB Bandwidth	>800 kHz

Parameter

Min

Typical

Max

Unit

Diode Capacitance

(f = 1MHz)

-

0.38

0.5

pF

Reverse Light Current (I )

(Vr = 0.9Vb)

-

10

50

nA

???

??=(V? (???)? ?? (???) ) / ???(???)
???? =4.5?? 0.1?5 μA=880 ?Ω

??? ??≤ ??? ?? ??
??≤ 0.18 pF at 1 MHz pole

???? ≥ (??+?? ) / (?? ?? ???)??? { ??= total capacitance of the photodiode and op-amp (0.5pF + ~ 5pF); }

≥ (? ??+?.???+?.?? ??) / (?????? ???.??^2)
?≥45 ???

Parameter	Required	LTC 6268(FET) [Linear Technology]	OPA354 (CMOS) [Texas Instruments]	AD8066(FET) (Analog Devises)
Supply Voltage	≤ 5V	5V	2.5 V to 5.5 V	5 V to 24 V
Quiescent Current	?	16.5mA	4.9 mA	7.2 mA
Output Voltage Range	0-5V	Rail-to-Rail	Rail-to-Rail	rail-to-rail
Gain-Bandwidth Product	>88 MHz	500 MHz	100-MHz	145 MHz
Input Bias Current	min	4 pA	3 pA	25 pA
Input Offset Current	?	2 pA	±50 pA	10 pA
Input Offset Voltage	min	2.5mV at Vcm = 1V; 4.5mV at Vcm = 2.2V	VS = 5 V, at TA = ?40°C to 125°C ±10mV	2.6 mV
Input Impedance	MΩ ?	>1000 GΩ	10 MΩ	1000 GΩ
Slew Rate	high	400 V/μS	150 V/μS	180 V/μS
Current Noise	min	5.5蹿础/√贬锄	50 fA/√Hz	0.6 fA/√Hz
Voltage Noise	min	4.3苍痴/√贬锄	6.5 nV√Hz	7 nV/√Hz
Input Capacitance	Very min	450 f F	2 pF	2.1 pF

Please correct me if am wrong....

Re: Need help to design a transimpedance amplifier

#90213

It's been 3 days since I posted and still have not shown up.

Regarding to noise pickup like from power supplies, power lines, tv etc. It's very common, any reasonable high transimpedance gain circuit need to have shield to cover the circuit. This kind of noise has nothing to do with the normal noise calculation like voltage and current noise. From my experience, other than the very high speed TIA that has feedback resistor under 1K, all the TIA circuit need to have shield. we just had to relayout a TIA circuit the contractor design that is only 1M feedback resistor. It was picking up noise big time.

For minimum of 200nA signal, that is huge signal, you don't even come close to the voltage and current noise issue. With a 50K feedback resistor, you have 10mV minimum signal. This is big signal!!!

Layout is critical, the -ve of the opamp has to be point to point with minimum trace length. Most people I've seen have long trace on the -ve input, that is inviting noise pick up. All these has nothing to do with LTSpice, it's good common sense EE.

Re: Takes two day for my post to show up

[email protected]

#90212

Some of you seem to be interested in long flaming wars on anything and do't understand the basics of business and how it operates and how acquisitions work. No amount of ?emails would help people who seem to feel they are experts on everything...

Bottom line:

Yahoo as we all knew and may still love will not exist in 1or 2 years.. It is unclear what it will morph into but one thing is for sure... even the meager support will disappear...

Part of being smart is figuring out how to gracefully transition this group to a nore supported and robust platform.. If the majority of you don't feel that we need to do something, then so be it..

Being forewarned is forearmed.

AG

Re: Takes two day for my post to show up

[email protected]

#90211

Some of you seem to be interested in long flaming wars on anything and do't understand the basics of business and how it operates and how acquisitions work. No amount of ?emails would help people who seem to feel they are experts on everything...

Bottom line:

Yahoo as we all knew and may still love will not exist in 1 or 2 years.. It is unclear what it will morph into but one thing is for sure... even the meager support will disappear...

Part of being smart is figuring out how to gracefully transition this group to a nore supported and robust platform.. If the majority of you don't feel that we need to do something, then so be it..

Being forewarned is forearmed.

AG

Re: PMBFJ620/2SK2145 or any other dual JFET-models exist for LTspice?

John Woodgate

#90210

开云体育

Do a web search for UPA63H. I don't know whether it will do what you want.

?

With best wishes DESIGN IT IN! OOO – Own Opinions Only

J M Woodgate and Associates Rayleigh England

?

Sylvae in aeternum manent.

?

Show quoted text

From: LTspice@... [mailto:LTspice@...]
Sent: Tuesday, August 9, 2016 6:49 PM
To: LTspice@...
Subject: [LTspice] Re: PMBFJ620/2SK2145 or any other dual JFET-models exist for LTspice?

?

Are there sny more around perhaps? Can't seem to find these in any shops.

Re: PMBFJ620/2SK2145 or any other dual JFET-models exist for LTspice?

#90209

? ?"Are there sny more around perhaps? Can't seem to find these in any shops."

I don't know what is available to you.? Maybe you should start by finding which dual JFETs you can buy, then look for their SPICE models.

By the way, I easily found SPICE models for a number of dual JFETs, by giving Google a try.? Search term: "dual jfet spice".? Your original question made it sound like you didn't find any.? That would be weird.

Andy

?

Re: Need help to design a transimpedance amplifier

#90207

...hmm, Michael...just "ball parkin'" some good values...enough to get the amplifier to work like an amplifier...modify at your digression.? I still have one msg that hasn't posted yet.? W. Warren

Re: PWL file in LTSPICE XVII not working while working in LT spice IV

#90205

Hello,

The bug with PWL-V-sources?in the 32 bit version XVII86.exe has been fixed in the new version from today.

Please update LTspiceXVII.

Tools -> Sync Release

Best regards,

Helmut

Re: Probing phase

#90204

Hello,

If one want the phase between two signals in the .AC analysis, then one should plot V(a)/V(b).?

This will plot the ratio |V(a)|/|V(b)| and the phase difference phi(a)-phi(b).

Best regards,

Helmut

Re: Probing phase

#90203

I'm not up to date yet with newer replies, but I want to respond to this, from the original message:

? ?"I don't seem to be able to use a differential probe to identify phase shift between two points.?"

A differential measurement doesn't show the phase between the two points.? It would show you the differential voltage between those two points. ?

It can show you the magnitude and the phase of that one voltage.? But it definitely would not be the phase between one voltage and the other.

Andy

Re: Takes two day for my post to show up

#90202

AG wrote:

? ?"Yahoo hs lost a lot of people and Verizon is not bothering to sign reqs to replace them..."

Why would Verizon have anything to do with jobs at a different company that they do not manage?

I think it's 'jumping the gun' quite a bit to expect Verizon to micro-manage a separate company they do not control.? Assuming that the purchase will be approved (in my future, I assume yours too), then Verizon would take ownership in 2017, and could start making management decisions.? My calendar still says 2016.? We're not there yet.

If there are unfilled jobs at Yahoo now, it is Yahoo's responsibility to handle them now.? Nobody else's.

Yahoo never had a good track record for support, now or 5 years ago.? We were complaining then about not having (e.g., hiring) employees in the right places.

But again, this is WAAAAY off-topic here.

(As for Yahoo Messenger, my personal opinion is to say "thank goodness, it's about time." ?It didn't work right, a lot of time it didn't work at all.? I think I'm glad Yahoo figured that out.? Again, Yahoo.? NOT Verizon, not Intel, not BP, not LTC.)

Andy

Re: PMBFJ620/2SK2145 or any other dual JFET-models exist for LTspice?

#90208

Are there sny more around perhaps? Can't seem to find these in any shops.

Re: Probing phase

#90206

Hello Steve

The error
" Error on line 101 : q13 n053 n062 vout-darlpp 0 qd44vh10 " appears because you have a bad

.SUBCKT 2SC6144SG 1 2 3 finishing by
.ensL

Correct .endL in .endS and your circuit will run.

It's not so obvious.

Regards
PhB

Re: Probing phase

Steve Kale

#90201

开云体育

Hi

I have added Reg Circuits.zip to the Temp files folder. ?It contains (1) the (old) reg circuits.asc file which has the problem you are exploring (just change the subcircuit Spice directive between a Spice directive and comment to see the error behaviour) plus (2) the log file and (3) Qd45vh10.txt which I believe is the only file missing to enable reg circuits.asc to run if ?both files are added to the folder I uploaded previously (Phase Analysis Rev B.zip). (You will see that Darlington.asc is basically just the bottom two schematics in reg circuits.asc with minor amendments.)

Thanks

Steve

Show quoted text

On 9 Aug 2016, at 16:31, basier.philippe@... [LTspice] <LTspice@...> wrote:

Hello Steve

"?I have pasted below the log file I get when (a) the 2SC6144SG subcircuit Spice directive is not made a comment?"

Coul you set "generate expanded listing" in control Panel \ Operatons and send again the file .log ?
Don't cancel the run.?
Upload in Temp it if it is too big.

" q13 n053 n062 vout-darlpp 0 qd44vh10" :

Regards
PhB

Re: Probing phase

#90200

Hello Steve

" I have pasted below the log file I get when (a) the 2SC6144SG subcircuit Spice directive is not made a comment "

Coul you set "generate expanded listing" in control Panel \ Operatons and send again the file .log ?
Don't cancel the run.
Upload in Temp it if it is too big.

" q13 n053 n062 vout-darlpp 0 qd44vh10" :

Regards
PhB

Re: Probing phase

Steve Kale

#90199

I tracked this down to a missing resistor. Stupid. ?Now off to the opticians for a new set of glasses…

I’ve updated the zip file in the Temp files section to Phase Analysis Rev B and deleted the old one.?

Show quoted text

On 9 Aug 2016, at 11:32, Steve wrote:

Now, the sub 1kHz behaviour remains the same as the image I had uploaded in the zip file (i.e. different from my new circuit) so I need to track down what’s causing that difference.

Re: Probing phase

Steve Kale

#90198

开云体育

Hi Philippe

I have pasted below the log file I get when (a) the 2SC6144SG subcircuit Spice directive is not made a comment and (b) I “OK” through the errors rather than cancelling the run.

Thanks for the correction to the .subckt. ?I got this from the On Semi website. Could this be a Spice D vs LTspice translation issue or just error?

Note I also found I had to alter their pin order in the line beginning Q1. They had:

Q1 2 1 3 ?C6144SG

But I’m not sure why this should give me the issue I encountered when the Spice directive wasn’t even being called upon…

Regards

Steve

Circuit: * /Users/steve/Desktop/Spice Modelling/Sziklai AD817A/Reg Circuits.asc

Error on line 101 : q13 n053 n062 vout-darlpp 0 qd44vh10