npn :
An NPN-type bipolar junction transistor.

The npn primitive represents a three-terminal NPN-type bipolar junction transistor. It implements an approximate Ebers-Moll transistor model described below:

    Ic = Is*(exp(Vbe/(N*VT))-1) - (1+1/Br)*Is*(exp(Vbc/(N*VT))-1)
    Ie = (1+1/Bf)*Is*(exp(Vbe/(N*VT))-1) - Is*(exp(Vbc/(N*VT))-1)
    Ib = Ie - Ic
    where VT = kT/q (25.695mV at 25C)

In the equations above, Is and VT change with the global parameter `global_temp, defining the temperature in Celsius (default: 25C). Specifically, the thermal voltage VT is proportional to the absolute temperature and the transport saturation current Is is proportional to exp(-VG0/VT), where VG0 is assumed to be 1.205V for silicon.

The parameters abstol and reltol set the error tolerance approximating these equations.

This primitive is a pseudo-module to describe a structural netlist of electrical circuits and not a behavioral model by itself. The XMODEL simulator extracts an event-driven behavioral model at run-time based on the circuit network described by these circuit-level pseudo-modules.

Input/Output Terminals

Name	I/O	Type	Description
c	input	xreal	collector
b	input	xreal	base
e	input	xreal	emitter
s	input	xreal	substrate

Parameters

Name	Type	Default	Unit	Description
Is	real	1e-16	A	transport saturation current at T=25C
N	real	1.0	None	emission coefficient
Bf	real	100.0	None	forward beta
Br	real	1.0	None	reverse beta
Va	real	`INFINITY	V	Early voltage
Cbe	real	0.0	farad	base-emitter capacitance
Cbc	real	0.0	farad	base-collector capacitance
Ccs	real	0.0	farad	collector-substrate capacitance
Cbs	real	0.0	farad	base-substrate capacitance
Ces	real	0.0	farad	emitter-substrate capacitance
abstol	real	1e-9	A	absolute tolerance
reltol	real	0.1	None	relative tolerance
m	real	1.0	None	multiplicity factor