OPA855: TIA with bootstarp stability issue

Tool/software:

Hello,

I am currently designing a TIA with a bootstrap circuit using the OPA855. Additionally, I am incorporating the OPA695 to achieve a higher gain. The target bandwidth is 100 MHz, with the maximum possible gain. The photodiode capacitance varies up to 120 pF. I have encountered a few questions during the analysis and simulation:

1. When I remove the feedback capacitor (1 pF), the bandwidth seems fine, but the final output (Vo2) appears unstable.

However, when I change the OPA695 supply to a single +5V, the bandwidth decreases slightly, and the output becomes stable. Could you help clarify why this is happening? The test was performed with a 30 MHz input signal.

2. I attempted a stability analysis by finding the phase margin at gain = 0. Could you please review this and let me know if I carried out the analysis correctly?

3. How can I calculate the output noise for this configuration?

Thank you
OPA855_Bootstrap.TSC