SinusoidalMixin format_spice_parameters incomplete AC statement #179
Description
Environment (OS, Python version, PySpice version, simulator)
macOS Mojave
python Python 3.7.6
Version: 1.3.2
ngspice version 31
Problem description
Not sure if this is due to the use of ngspice version 31 compared the currently supported version 30 but the AC statement generated by PySpice does not work.
The filter/low-pass-rc-filter.py sample fails due to an incomplete AC statement in the PySpice generated netlist:
.title Low-Pass RC Filter
Vinput in 0 DC 0V AC SIN(0V 1V 50Hz 0s 0Hz)
R1 in out 1kOhm
C1 out 0 1uF
.options TEMP = 25°C
.options TNOM = 25°C
.ic
.ac dec 10 1Hz 1MegHz
.end
If I pass this netlist to ngspice directly it complains, but there is no error return from the shared library interface used by PySPice ?!?
The problem is in line:
Vinput in 0 DC 0V AC SIN(0V 1V 50Hz 0s 0Hz)
the AC statement lacks the voltage amplitude i.e. to work, the line should read
Vinput in 0 DC 0V AC 1V SIN(0V 1V 50Hz 0s 0Hz))
The ngspice manual says it can be omitted and defaults to 1V but that does not seem to be the case.
Solution
Change the format statement in SinusoidalMixin. format_spice_parameters as below by adding the Signal amplitude as AC amplitude setting
def format_spice_parameters(self):
sin_part = join_list((self.offset, self.amplitude, self.frequency, self.delay, self.damping_factor))
return join_list((
'DC {}'.format(str_spice(self.dc_offset)),
'AC {0} SIN({1})'.format(str_spice(self.amplitude), sin_part)
# 'AC SIN({})'.format(sin_part),
))
With this modified format_spice_parameters function the filter/low-pass-rc-filter.py sample works as expected.