# What is the role of R1/C1, R3 in this slicer circuit?

I found the following data slicer circuit: simulate this circuit – Schematic created using CircuitLab

The input is a simple NRZ (PAM-2) signal between "Vhigh" and "Vlow" (=around 0V) where each bit has a length "Tbit". Due to bandwidth limitation, the input is also not a perfect square pulse but can be modeled as being filtered with a simple first-order lowpass with cutoff "fc".

I can't wrap my head around why exactly the author or this circuit came up with the idea of adding R1+C1 (and R3). I cannot find a single where adding R1+C1 would not make things worse (after all, it's a highpass/differentiator). Similarly, I neigher see the purpose for R3, nore can I find a case where it would be helpful.

In LTspice, the circuit works best if I kick out R1,C1 and R3 and make R2*C3 = 5/Tbit (as suggested in https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3671.html).

But I don't want to remove just just because I don't understand it...

EDIT: Maybe this was a "hard" question so I changed it to merely understand what this thing is doing...

• It all depends on how much you want to 'slice'. You'd need to know how you want to change the waveform and generate requirements for that. In short, you need to know Vin and Vout then you can define the transfer function of the opamp. – Voltage Spike Jul 15 at 20:19
• I am sorry if the question was not quite clear but this is exactly my question: If I give you Vhigh and Vlow (and Tbit and fc and possibly the bit pattern) HOW do I set R1,C1,R2,C2,R3 and possibly the hysteresis of the comparator? (EDIT: I can add a picture of a sample signal) – divB Jul 15 at 20:28
• Note that the NCS2200 is a low voltage comparator with a 1 uS response time, but with proper RC values it should be able to handle high baud rates under 115 Kbaud. It is specific to being a ultra-low power comparator for battery devices. – user105652 Jul 15 at 21:12
• Any idea what the differentiator (R1+C1) could be good for? Why do we need R3? All slicers I find are much more simple and would only consist of R2 and C2... – divB Jul 16 at 5:40