#!/usr/bin/env python
# coding: utf-8

# n-MOSFET Transistor
# ===================
# 
# This example shows how to simulate the characteristic curves of an nmos
# transistor.
# 

# In[ ]:


import matplotlib.pyplot as plt


import PySpice.Logging.Logging as Logging
logger = Logging.setup_logging()


from PySpice.Doc.ExampleTools import find_libraries
from PySpice import SpiceLibrary, Circuit, Simulator, plot
from PySpice.Unit import *


libraries_path = find_libraries()
spice_library = SpiceLibrary(libraries_path)




# We define a basic circuit to drive an nmos transistor using two voltage
# sources. The nmos transistor demonstrated in this example is a low-level
# device description.
# 

# In[ ]:


circuit = Circuit('NMOS Transistor')
circuit.include(spice_library['ptm65nm_nmos'])

# Define the DC supply voltage value
Vdd = 1.1

# Instanciate circuit elements
Vgate = circuit.V('gate', 'gatenode', circuit.gnd, 0@u_V)
Vdrain = circuit.V('drain', 'vdd', circuit.gnd, u_V(Vdd))
# M <name> <drain node> <gate node> <source node> <bulk/substrate node>
circuit.MOSFET(1, 'vdd', 'gatenode', circuit.gnd, circuit.gnd, model='ptm65nm_nmos')



# We plot the characteristics $Id = f(Vgs)$ using a DC sweep simulation.
# 

# In[ ]:


simulator = Simulator.factory()
simulation = simulator.simulation(circuit, temperature=25, nominal_temperature=25)
analysis = simulation.dc(Vgate=slice(0, Vdd, .01))

figure, ax = plt.subplots(figsize=(20, 10))

ax.plot(analysis['gatenode'], u_mA(-analysis.Vdrain))
ax.legend('NMOS characteristic')
ax.grid()
ax.set_xlabel('Vgs [V]')
ax.set_ylabel('Id [mA]')

plt.tight_layout()