discrete photodiode amplifier

[T8P1]

Hi

I have to design a discrete Photodiode Amplifier with a flat bandwidth to 50MHz and a current input noise below 3pA/Hz. I get from the photodiode 0-50uA dc and 35pA ac.
I split the ac and dc current to amplify them separatly. The dc part is no problem, but the ac part.
My opinion is to amplify it with a jfet, think to try the bf862, with pnp cascode and a emitter follower.
Have somebody a better idea?

Regards

 

[Laplace]

Have you looked at the TI OPA847? It is billed as a wideband, ultra-low noise operational amplifier suitable for making a transimpedance amplifier for photodiodes. I've been trying to use it with a PIN photodiode as a high-gain sub-microsecond single event detector.

 

[T8P1]

At first, the OPA847 looks nice, but its current input noise with 2.5pA/Hz is near the limit.