I am trying to build a Schmitt trigger from a pair of BJTs to convert a sine to a square wave.
The sine wave is from a Colpitts oscillator running at over 150 MHz. I want to measure the frequency using something like the SN74LV4040, which is why I want to square the sine wave somewhat.
This is the relevant part of the Schmitt trigger (with V1 representing the oscillator). Emitter current was set to 2 mA, high voltage to 3 V, low voltage to 2 V.
But this is the output I get in LTspice.
Why am I getting a sine wave output from the Schmitt trigger?
This is the whole schematic (with some voltages plotted), if that helps: