I want to use the signal from a GPS disciplined oscillator (GPSDO) as a clock signal for a microcontroller.
The GPSDO outputs a 10 MHz square wave between 0 V and 3.3 V designed to drive into a 50 Ω characteristic impedance.
This is delivered to my circuit over a short (500 mm or so) length of coaxial cable. My circuit terminates it with 50 Ω to GND (which also reduces the peak voltage of the square wave to about 1.5 V).
I'm using a Schottky diode to clamp the signal (through a 2200 Ω resistor) to the 3.3 V rail to protect a microcontroller from being powered by the square wave when the 3.3 V rail is turned off.
As a result of this, the final clock signal is reduced to a slightly curved triangular wave between 1.3 V and 1.78 V (in other words, a 480 mV pk-pk with a +1.55 V DC offset). The waveform is very clean and appears free from any distortions that might make it unsuitable as a clock signal. However the amplitude is very small and it is currently unbuffered.
What could I use to amplify this signal into the microcontroller? The microcontroller expects a 0 - 3.3 V signal, but I think it's fairly tolerant of anything better than 2 V pk-pk centred on 1.65 V.
So far I have tried to use an NPN BJT transistor (2N2222) as a simple voltage amplifier but I couldn't get that to work. I wondered about using something like an LM741 op-amp but the 1.5 MHz bandwidth is insufficient.