For the OA I've used LM324 whose output voltage is Vcc-1.5V.So for my case I've made these calculations with input voltage of 10 V.

I have τ=100uS.UTHL= ±1mV UTHH=±1V

I can't reach the required working frequency range of 1kHz-100kHz

These are my calculations so far I've probably messed some formula to achieve so low frequency.