# (PSPICE) Memristor-Based IF Neuron Circuit: What is this NMOS?

This is a memristor-based IF neuron circuit. My question is, i'm trying to simulate this circuit in PSPICE. However, I am unsure what the N-MOSFET characteristics (M1) are in the circuit diagram. I do not see any parameters in the paper. Do I just choose an arbitrary N-Mosfet from the mosfet library in PSPICE? What about it's Pspice model characteristics (vdd, bias current, etc)?

I don't see any characteristics about the MOSFET in the paper...unless i'm just missing it.

• What tells you it is NMOS? – Andy aka Feb 25 '18 at 9:55
• @Andy aka: the symbol; the simplified symbol for a P-MOSFET would have an "inverting circle" at the gate. – Curd Feb 25 '18 at 11:20

## 1 Answer

It seems that $A_2$ works as comparator (with hysteresis, because of $R_2$) so its output is digital. Also the following inverter operates digitally.

So you can assume that the MOSFET is used simply as analog switch and the only thing you have to care about is that it is turned on properly when $V_K$ is high, i.e. that $V_{th}$ of the MOSFET (not the $V_{th}$ shown in the circuit diagram) is small enough; or just use the more abstract voltage controlled Switch element of PSPICE instead of a MOSFET: • That makes a lot of sense, didn't even come to me about the output as a digital signal since it's being inputted to an inverter. Followup question, how does it alternate between turning on and off when Vmem > Vth? Since i'm assuming this should generate 'spikes', as a neuron behaves. – tnet Feb 25 '18 at 8:04
• @tnet: $A_2$ turns on/off depening on $V_x$ and $V_{REF}$. ($A_1$ with inputs $V_{mem}$ and $V_{th}$ works not as comparator but as integrator) – Curd Feb 25 '18 at 8:10