Adding lossless transmission line

PySpice/Spice/BasicElement.py

@@ -952,7 +952,7 @@ def __str__(self):
         if self.table is not None:
             # TABLE {expression} = (x0, y0) (x1, y1) ...
             table = ['({}, {})'.format(x, y) for x, y in self.table]
-            spice_element += ' TABLE {%s} = %s' % (self.expression, join_list(table)) 
+            spice_element += ' TABLE {%s} = %s' % (self.expression, join_list(table))
         return spice_element
 
 ####################################################################################################
@@ -1420,6 +1420,68 @@ def source(self):
     def substrate(self):
         return self.pins[3]
 
+####################################################################################################
+
+class TransmissionLine(TwoPortElement):
+
+    """This class implements a lossless transmission line.
+
+    Spice syntax::
+
+        TXXXXXXX N1 N2 N3 N4 Z0=VALUE <TD=VALUE> <F=FREQ <NL=NRMLEN>>
+
+    where TD or F,NL must be specified.
+
+    Keyword Parameters:
+
+      :attr:`impedance`
+         alias:`Z0`
+
+      :attr:`time_delay`
+         alias:`TD`
+
+      :attr:`frequency`
+         alias:`F`
+
+      :attr:`normalized_length`
+         alias:`NL`
+
+    Attributes:
+
+      :attr:`impedance`
+
+      :attr:`time_delay`
+
+      :attr:`frequency`
+
+      :attr:`normalized_length`
+
+    Note: Either time_delay or frequency must be given.
+
+    """
+
+    alias = 'TransmissionLine'
+    prefix = 'T'
+
+    def __init__(self, name,
+                 input_node_plus, input_node_minus,
+                 output_node_plus, output_node_minus,
+                 *args, **kwargs):
+
+        if not (('time_delay' in kwargs) ^
+                (('frequency' in kwargs) & ('normalized_length' in kwargs))):
+            raise NameError('Either TD or F,NL must be specified')
+
+        super().__init__(name,
+                         output_node_plus, output_node_minus,
+                         input_node_plus, input_node_minus,  # Fixme: inverted inputs
+                         *args, **kwargs)
+
+    impedance = FloatKeyParameter('Z0', default=50)
+    time_delay = FloatKeyParameter('TD')
+    frequency = FloatKeyParameter('F')
+    normalized_length = FloatKeyParameter('NL')
+
 ####################################################################################################
 #
 # End

doc/sphinx/source/examples/index.rst

@@ -19,3 +19,4 @@ This section has 13 sub-topics and 25 examples.
   spice-parser/index.rst
   transformer/index.rst
   transistor/index.rst
+  transmission-lines/index.rst

doc/sphinx/source/examples/transmission-lines/index.rst

@@ -0,0 +1,11 @@
+
+====================
+ Transmission Lines
+====================
+This section has 1 example.
+
+
+.. toctree::
+  :maxdepth: 1
+
+  time_delay.rst

doc/sphinx/source/examples/transmission-lines/time_delay.rst

@@ -0,0 +1,43 @@
+
+.. include:: /project-links.txt
+.. include:: /abbreviation.txt
+
+===============================================
+True-time Delay with Lossless Transmission Line
+===============================================
+
+.. getthecode:: time_delay.py
+    :language: python
+
+.. code-block:: python
+
+    import PySpice.Logging.Logging as Logging
+    from PySpice.Spice.Netlist import Circuit
+    import matplotlib.pyplot as plt
+    from PySpice.Probe.Plot import plot
+
+    logger = Logging.setup_logging()
+
+    ####################################################################################################
+
+    circuit = Circuit('Transmission Line')
+    circuit.Pulse('pulse', 'input', circuit.gnd, 0, 1, 1e-9, 1e-6)
+    circuit.R('load', 'output', circuit.gnd, 50)
+    circuit.TransmissionLine('delay', 'input', circuit.gnd, 'output', circuit.gnd, impedance=50, time_delay=40e-9)
+
+    simulator = circuit.simulator(temperature=25, nominal_temperature=25)
+    analysis = simulator.transient(step_time=1e-11, end_time=100e-9)
+
+    ####################################################################################################
+
+    plt.figure(None, (20, 6))
+    plot(analysis['input'])
+    plot(analysis['output'])
+    plt.xlabel('Time [s]')
+    plt.ylabel('Voltage (V)')
+    plt.grid()
+    plt.legend(['input', 'output'], loc='upper right')
+    plt.show()
+
+.. image:: time_delay.png
+  :align: center

examples/transmission-lines/time_delay.py

@@ -0,0 +1,27 @@
+import PySpice.Logging.Logging as Logging
+from PySpice.Spice.Netlist import Circuit
+import matplotlib.pyplot as plt
+from PySpice.Probe.Plot import plot
+
+logger = Logging.setup_logging()
+
+####################################################################################################
+
+circuit = Circuit('Transmission Line')
+circuit.Pulse('pulse', 'input', circuit.gnd, 0, 1, 1e-9, 1e-6)
+circuit.R('load', 'output', circuit.gnd, 50)
+circuit.TransmissionLine('delay', 'input', circuit.gnd, 'output', circuit.gnd, impedance=50, time_delay=40e-9)
+
+simulator = circuit.simulator(temperature=25, nominal_temperature=25)
+analysis = simulator.transient(step_time=1e-11, end_time=100e-9)
+
+####################################################################################################
+
+plt.figure(None, (20, 6))
+plot(analysis['input'])
+plot(analysis['output'])
+plt.xlabel('Time [s]')
+plt.ylabel('Voltage (V)')
+plt.grid()
+plt.legend(['input', 'output'], loc='upper right')
+plt.show()