current to voltage converter urgent help..vishnukiran17@gmail.com

[vishnu17]

i need a circuit which can converter 30nA current to 4vp-p

 

[crutschow]

Is that 30nA p-p?

 

[vishnu17]

30nA current as input

my project is converting the current from an photodetector which is of about 30 nA to o/p 4vp-p

the circuit may be done in two step
1. frist converting the current to voltage and then amplify
2. amplify then conversion to voltage

 

[vishnu17]

yaa...
my project is converting the current from an photodetector which is of about 30 nA to o/p 4vp-p

the circuit may be done in two step
1. frist converting the current to voltage and then amplify
2. amplify then conversion to voltage

 

[KeepItSimpleStupid]

There is a "T" network that can be used that avoids the use of high value resistors. The selection of the OP amp is critical.

What is the bias on the photodector? What is the bandwidth required?

 

[crutschow]

An op amp connected as a trans-impedance amplifier will convert the current to a voltage. A 10 megohm feedback resistor will give a peak output of 0.3V. You can then voltage amplify that with a gain of 13.3 to give the desired 4V peak.

The op amp must have a small input bias current (probably need to have a FET input) and gain-bandwidth sufficient for your signal bandwidth requirements.