Preamplifier which can convert fento-amp current into voltage

[misha82]

hi i want to design a preamplifier which can convert fento-amp current in to voltage.
can somebody give me some basic help.
max value of resistance available is 100G ohm.
thanx

 

[misha82]

Re: Preamplifier for very low current

hi can any body tell me witch opamp should i use for this purpose.

 

[IanP]

Re: Preamplifier

Fentoamps --> extremely difficult issue ..
About pA range you can read in the following publication:
**broken link removed**

Regards,
IanP

Abstract: A new bipolar op amp design has advanced the state of the art by reducing offset voltage and bias current errors. Its characteristics are described here, indicating an ultimate input resolution of 10 mV and 1 pA under laboratory
conditions. Practical circuits for making voltmeters, ammeters, differential instrumentation amplifiers and a variety of other designs that can benefit from the improved performance are covered in detail.