Current limiter for TIA, realizing dc current source

[Kakeh]

Problem:

my photo diode receives pulses of width 10ns-150ns and repeating at rate of 1Hz-50KHz

the current from photo diode depending on incident light can go from 10nA-100mA, so i have two photo diodes to cover the dynamic range, what i want to do is limit the current from a photo diode to 5mA let's say in one channel

Approach Followed:

in search i found some thing similar to my need here

the patent claims: in the picture the current sources 30 and 38 are the maximum current at which the TIA saturates, as soon as the TIA saturates, the schottky bridge isolates the TIA from source,

i have less idea whether the patent circuit can work for pulsating current, but when i tried the results were nice

Design Problem:

how to select the schottky diode and also the pJFET for much better response

if you see schematic i have given a trail of pJFET of all available with LTspice, and same with schottky

How to realize 30 and 38 on practical circuit ?, how can i create stable dc current sources ?

 

[CWatters]

Try googling transistor current sink. Finds pages like..

https://en.wikipedia.org/wiki/Current_source#Simple_transistor_current_sources

 

[CWatters]

Actually now I've read you post again... Are you after a current source/sink or a current limit? They are different.