Tell me more ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.
up vote 2 down vote favorite

I have designed a transimpedance amplifier using OPA355, the datasheet suggest this Opamp can go down to 2.5V and still works however I cannot get it to work at 3V. If I provide 5V supply, everything works, when I reduce to 3V, things stop working.

I will further debug this but I am looking for a reliable 3V single supply OpAmp that I will use as a transimpedance amplifier. My signal is about 3MHz and I deal with small signals so I need something with relatively low noise.

I need help from the masters as I am looking for a proven part that somebody here made it work before as opposed to perfect datasheet part.

share|improve this question
2  
Please post your schematic. TI doesn't generally lie on their datasheets, so maybe there's a way to get the OPA355 working for you at 3V. – markrages♦ Oct 26 '11 at 4:58
2  
As well as the schematic, defining "things stop working" would be useful too. – Oli Glaser Oct 26 '11 at 5:29
1  
Yes, this sounds more like a circuit problem than the opamp working at 2.5V by mysteriously not at 3V. – Olin Lathrop Oct 26 '11 at 12:04
I had a 2.5v bias on the + port, at 3.3v opamp doesnt like it. When I reduce the bias to 1.5 things start to work. Thanks guys. I will do more tests and let you know of interesting stuff comes up. – Frank Oct 27 '11 at 1:51
You are not respecting the common-mode range of the op-amp. Please post your circuit. – markrages♦ Oct 27 '11 at 1:59

1 Answer

up vote 2 down vote

Note that the OPA355 input common mode range extends to 0.1 Volt below ground BUT only to within 1.5V of Vdd. We'd need to see your circuit to know if this was significant. Also Vout is "not quite" rail to rail. OPA355 datasheet

I'll not claim to be a master in this context, but the following may be useful:

Similar specs to OPA355in many areas.
Apparently much superior CMRR.
2.75 vs 5.8 nV/Hz^2 Similar GBW
Superior output voltage swing (especially +ve)
280 vs 360 V/uS slew (ie slower)

LTC6252 Datasheet
720 MHz GBW
400MHz -3dB point as buffer
Input common mode rail to rail.
2.5V to 5.25V operation and fully specified at 2.7V and 5V.
CMRR 105 dB ! (!!!!!)
Noise 2.7 nV.Hz^-2
280 V/uS slew :-) :-) :-) :-) :-)
$4.59/1 in stock Digikey (Cheap considering spec).
Single, dual and quad versions available.

enter image description here

share|improve this answer
You got it Russell. – Frank Oct 27 '11 at 1:52

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.