current to voltage converter

Thread Starter

Mabunda

Joined Mar 9, 2004
2
What must i consider when using current to voltage converter, and what are the op_ amps parameters must i consider or perhaps help me with good transducer
amolifiers.

Thank you
Themba Mabunda : :lol:
 

mozikluv

Joined Jan 22, 2004
1,437
:) hi,

here's a few things you should consider when you are going to use op-amps,
1. Vcc
2. slew rate
3. frequncy response
4. closed loop response
5.output impedance vs. frequency
6. relative frequency response vs.frequency
7. low noise or ultra low noise

many more.......... :)

whatever op-amp you will use, read very well the datasheet and you will get what the best and worst of the op-amp you are using :blink:
 

Dave

Joined Nov 17, 2003
6,970
In addition to what mozikluv has said, have a look at the Transresistance Ampilfier.

It is essentially a current to voltage convertor which takes an input as a current and produces a voltage output. For all intents purposes its very like an inverting amplifier and considerations should be given as if it were an inverting amplifier.

If I can find a link to the Transresistance amplifier I will post it up for you to have a look.
 

mozikluv

Joined Jan 22, 2004
1,437
:) hi mabunda & haditya,

try this sites about transresistance amplifier

http://ieeexplore.ieee.org/xpl/abs_free.js...arNumber=658624
http://www.engin.umd.umich.edu/~fmeral/CIR...t%205/Opamp.pdf
http://grove.ece.iastate.edu/docs/papers/20000806.pdf

you will learn a lot about transresistance amplifier.

have been using these as part of my audio power amp designs. :) however based on your qualification as you have mentioned in one of your post, that topic might be out of your range but it does not mean you won't understand any of them. :)
 

Dave

Joined Nov 17, 2003
6,970
Originally posted by haditya@Mar 28 2004, 06:02 AM
:huh: someone help me on this what does one mean by a "current to voltage convertor" :unsure:
A current to voltage convertor is essentially a device which takes a current as an input and provides a voltage as an output.

Look here about a third of the way down the page to see a basic model for a current to voltage convertor, remember this doesn't necessarily represent what is inside such a device. There also some information on a voltage to current amplifier (or Transconductance Amplifier).
 

mozikluv

Joined Jan 22, 2004
1,437
:) hi mabunda,

since you are in astage where you want to build your project, your choice of using a current feedback amp. is just right in converting the small output current of a photo-diode transducer to a fast responding voltage.

what should really concern you what component values should you use on your resistors and capacitors. with a CFA it has an internal buffer at the inverting node of the op amp and internal output impedance (Ro) (this can be seen in the datasheet in whatever CFA you will use). the photo-diode has an output capacitance of about 10 - 200pf which introduces a zero gain at about 1/2piRoCin.

for you to counteract the effect of zero gain you have to use a feedback capacitor in parallel with Rf. this way you're introducing a low frequency pole as determined by this equation 1/2piRfCf and an inconsequential zero determined by this equation 1/2piRoCf

if Cin is large enough, say 0.1uf or 0.15uf the closed loop phase shift will be approaching -180 degrees at the cross-over frequency where open loop transimpedance gain will cross the noise gain function.

at the output put an RC filter

if i sound greek, just holler, we will just have to try another approach. :)
 

sjoshidce

Joined Sep 18, 2006
1
hi,
plz send me cicrcuit for current to voltage convertor

thanks
sunil




In addition to what mozikluv has said, have a look at the Transresistance Ampilfier.

It is essentially a current to voltage convertor which takes an input as a current and produces a voltage output. For all intents purposes its very like an inverting amplifier and considerations should be given as if it were an inverting amplifier.

If I can find a link to the Transresistance amplifier I will post it up for you to have a look.
 
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