OpAmp Design Questions for Transimpedance Amplifier
With 1mA input across 470 ohms, that Vout of 0.47 volts will hardly challenge the slewrate; 0.47v is more in small signal region. 

A high-capacitance sensor will kill your speed. And a slow-test-photon-pulse will confuse the measurements. What are your params?

And is the 50_ohm load the problem?

Consider, to debug the circuit, dropping in a common-base NPN transistor. If that is slow, then the sensor and the parasitic Vin node capacitance is the impairment.







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