# How to get the full range of output voltage (0-5V) from a differential pair circuit as a schmitt trigger?

The circuit works in the hysteresis range of 2.5V - 1.5V. The output voltage does not reach the full range because I have a dc offset of 1.8V. What's the easiest way to get the full output range with this kind of circuit? Adding a capacitor removes dc offset, but I need another gain stage to get the 0-5V output... Thanks

• The output voltage does not reach the full range Think about what the lowest output voltage will be when using this circuit. Hint: assume Q1 is open (not conducting) and Q2 is closed (fully conducting), then I see a voltage divider, do you too? What's the easiest way to get the full output range with this kind of circuit? There is no way, this circuit cannot do it. Explain why you don't use an opamp (or comparator) to make a Schmitt-trigger like almost everyone else. Feb 18, 2021 at 16:24
• @Bimpelrekkie I design this as part of the exercise, but as a circuit at the clock input. Feb 18, 2021 at 16:39