Dear all,
I'm designing a diode test fixture and I'm having problem with the analog inteface, please help me out. In my design, I intend to use INA116 or INA101 and a Wheatstone bridge to form a circuit to test diode leakage current on reverse bias. In this configuration, the diode (DUT) will be connected in parallel with on of the legs of the bridge, and the signal will be amplified through differentiator configuration. This part is the front-end interface which will be connected to a MCU. Could you please evaluate if this idea is feasible. Are there any other better methods to test reverse leakage current of the diode?
If any of you have worked with this before, please share some ideas. Detecting ultra low current is extremly difficult for me. Otherwise, please guide me to some links or sources where I can find the circuit, ideas. Any inputs would be greatly appreciated. Thanks in advance.

Here is the circuit.
http://www.8052.com/users/my8052/Bridge.JPG
This is just the copy and paste from the different datasheet. All value is not the actual one. The voltage applied to diode should be around 20V in order to detect 5nA leakage according to diode datasheet.
http://www.fairchildsemi.com/ds/1N%2F1N4004.pdf

Best Regards,
T.L