My goal is to input 30MHz sine pulses, with a pulse width of 10us and gap of 90us between the pulses. The circuit should convert this pulse train to a TTL signal that goes from 0 to 5 volts.
To achieve this I run the pulse train through a peak/envelope detector, consisting of a diode, a resistor and a capacitor. This will capture the peak of the pulse. These peaks are then recieved by a comparator that outputs 5 volts whenever the input voltage exceeds the 1 volt reference voltage.
Green signal is the output from the peak/envelope detector.
When trying to verify this on a breadboard I ran into a problem. The peak/envelope detector does not detect the peak of the input signal but instead outputs the exact same signal as the input (I did not save the oscilloscope picture.) My concern is that the diode is not fast enough to handle signals of this frequency (30MHz.)
When looking at the output of the peak/envelope detector in LTSpice it looks fine:
This (below) is what an input pulse looks like after the diode.
Does anyone have any thoughts about this?