Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Looking for SPICE Model of PNP


Advanced Member level 3
Nov 3, 2018
Reaction score
Trophy points
Activity points

I am wondering how can I add "FMMT591" SPICE Model in LT SPICE Library ? There is no option of create new symbol.


  • Untitled 732.png
    Untitled 732.png
    71 KB · Views: 28
Last edited:
I already know this procedure. The problem is that there is no option of Create Symbol. I have attached a screenshot in the first post.
I just manage to include the SPICE Model. I am not sure if it is working fine or not.

In PNP transistor, to turn on the transistor, the base voltage has to be below -0.6 V. Such that emitter to base is +0.6 V forward bias. But in simulation it is not like that. It seems to be conducting.

When the transistor is not conducting (base voltage is higher then -0.6 V) the collector voltage should be the supply voltage.


  • Untitled 734.png
    Untitled 734.png
    45.9 KB · Views: 12

you have only changed the reference designator from "Q1" to FMMT591. You have to change the "value" PNP to FMMT591, see my attached image in the previous reply.

I have changed the value to "FMMT591". I am not sure about Prefix. It is QP. Kindly have a look at the simulation and let me know if I need to change anything more.


  • Untitled 735.png
    Untitled 735.png
    59.4 KB · Views: 16
Decrease the increments in your DC analysis from 10 (at the moment: .dc Vin 0 -3.3 10) to e.g. 0.01. That's your voltage step/increment. At the moment you only cover "1" step, as your voltage span of interest is only from 0V to -3.3V.

I thought it as number of steps. But now I understand that it is one voltage step/increment. I will change it and run the simulation again. Thanks you notice.
I have changed the supply to -5V then it start working.

I am still wondering about Prefix. It is QP. Do we have a list of Prefix for different devices ?


  • Untitled 736.png
    Untitled 736.png
    38.8 KB · Views: 13
BJT prefix is Q, npn or pnp is decided by model. It's generic SPICE syntax, you can refer to LTspice help
Q. Bipolar Transistor

Symbol Names: NPN, PNP, NPN2, PNP2

Syntax: Qxxx Collector Base Emitter [Substrate Node] model [area] [off] [IC=<Vbe, Vce>] [temp=<T>]


Q1 C B E MyNPNmodel.model MyNPNmodel NPN(Bf=75)

Bipolar transistors require a model card to specify its characteristics. The model card keywords NPN and PNP indicate the polarity of the transistor.

LaTeX Commands Quick-Menu:

Part and Inventory Search

Welcome to