Need help selecting an op amp

I am a digital designer, and a bit out of my element using op amps.

I need to amplify a pulse stream using a single op amp stage [board already designed/fabbed around an SOT23-5 package]. I am currently using
I need the highest gain I can get [10-20mv input or less?], and the fastest response time [better than 1us pulses?]. With a 3.6V circuit, I need a rail-2-rail output.
I am not clear on which parameters of the op amp are the most important. I've been looking over numerous ICs, but am not sure how to pick the best candidate. I have tried several TI parts, [I know, blasphemy!], OPA349 and OPA333 with lower than desired frequency response. Several AD parts - AD8051, AD8691, AD8605, etc seem to have better specs, but I am not clear on which specs really matter for this application.

Any thoughts would be most appreciated!

  • I should have commented:

    The circuit is configured as a simple, inverting amp, with a single supply.

  • Thank you for responding, Harry. As I said, I am not much on amps, Op or otherwise.

    I have the + input held at about 10% of supply, bypassed with a cap.

    The incoming pulse is referenced to ground.

    My goal is to reproduce the incoming pulse [except inverted]. The original pulse is close to 50% duty cycle.

    Curiously, as the pulse rate goes up, the apparent duty cycle changes from around 50% going down to zero. I am not clear on why that happens; possibly due to the slew rate of the amp?

    Yes, it starts as a digital signal, seriously attenuated due to transmission circumstances. I need to reproduce it as best as possible, and then feed it into a micro.

    Gain accuracy is irrelevant, as is any phase shifting. My only concern is to recover enough pulse amplitude for the micro to reliably "see" it.

    Right now, I get good pulse reproduction up to about 50-100 KCPS rep rates, then the pulse dies off to nothing. I need about 10X that frequency capability.

    I thought about a comparator, but I know even less about using them. Sorry for the seemingly ignorant background, I live in a pure digital world, and anything analog is foreign.