PWM square wave oscillator with duty cycle controlled by an input ranging from 0-1, where 1 is 100% duty cycle.

The nodes are:

'ctrl' - An inmput with voltage from 0 to 1, controlling the duty cycle.
'outp' - Positive output.
'outn' - Negative output (need not be tied to ground).

Instance Variable	Vhigh	The high output voltage.
Instance Variable	Vlow	The low output voltage.
Instance Variable	fs	The frequency (Hz).
Instance Variable	tt	The transition time from Vlow to Vhigh and vice versa.
Instance Variable	tRiseFall	Set to a rise/fall time in seconds to limit output slew rate for realism or convergence.
Instance Variable	t0	An optional delay (seconds) from TRAN start before the start of the pulse train.
Method	setup_oscillator	Constructs a triangle-wave oscillator with my frequency fs and a ground-referenced output at n1.
Method	setup_ctrl_atanh	Constructs a TABLE E-source that implements the following function, which Ngspice seems to have trouble calculating consistently for some stupid reason:
Method	setup_comparator	Constructs a smooth-edged comparator intended for use with a triangle wave on input n1 and a (relatively) constant voltage between 0 and 1 on input n2.
Method	setup	Defines the subcircuit netlist for a PWM oscillator with simulation-friendly transitions from Vlow to Vhigh and back again.

Inherited from NodeStuff (via Subcircuit):

Instance Variable	shunts	A dict of current sensing V elements with the pairs of nodes they connect.
Class Variable	debug	A `Bag` that gets set `True` for all instances to log info about each `setup` call.
Class Method	autoName	Undocumented
Method	setupResults	Undocumented
Method	fill	Undocumented
Method	nodeCheck	Call with the circuit building tool f and a sequence of nodes provided to this `Include` or `Subcircuit`.
Method	rawNetlist	Get lines of a raw netlist from a search hierarchy of possible sources.
Method	shunt	Call to insert a current-measuring shunt and add an entry to my `Elements` baton's dict of shunts.
Method	raw	See `Elements.raw`.
Method	iNode	See `Elements.iNode`.
Method	ground	See `Elements.ground`.
Method	sca	See `Elements.sca`.
Method	sca6	See `Elements.sca6`.
Class Method	_libDir	Undocumented
Method	_strippedLines	Undocumented
Method	_call_setup	Calls my `setup` method (almost always your override of that method, actually) and processes any return value.

Inherited from NodeStuff (via Subcircuit):

Instance Variable	shunts	A dict of current sensing V elements with the pairs of nodes they connect.
Class Variable	debug	A `Bag` that gets set `True` for all instances to log info about each `setup` call.
Class Method	autoName	Undocumented
Method	setupResults	Undocumented
Method	fill	Undocumented
Method	nodeCheck	Call with the circuit building tool f and a sequence of nodes provided to this `Include` or `Subcircuit`.
Method	rawNetlist	Get lines of a raw netlist from a search hierarchy of possible sources.
Method	shunt	Call to insert a current-measuring shunt and add an entry to my `Elements` baton's dict of shunts.
Method	raw	See `Elements.raw`.
Method	iNode	See `Elements.iNode`.
Method	ground	See `Elements.ground`.
Method	sca	See `Elements.sca`.
Method	sca6	See `Elements.sca6`.
Class Method	_libDir	Undocumented
Method	_strippedLines	Undocumented
Method	_call_setup	Calls my `setup` method (almost always your override of that method, actually) and processes any return value.

Vhigh =

The high output voltage.

Vlow =

The low output voltage.

fs =

The frequency (Hz).

tt =

The transition time from Vlow to Vhigh and vice versa.

tRiseFall =

Set to a rise/fall time in seconds to limit output slew rate for realism or convergence.

t0 =

An optional delay (seconds) from TRAN start before the start of the pulse train.

def setup_oscillator(self, f, ts, n1):

Constructs a triangle-wave oscillator with my frequency fs and a ground-referenced output at n1.

Returns the rise/fall time, which is a little bit less than half the period, owing to non-zero pulse width.

def setup_ctrl_atanh(self, f, a, b, n1, n2):

Constructs a TABLE E-source that implements the following function, which Ngspice seems to have trouble calculating consistently for some stupid reason:

   V(n2) = a*atanh(b*(V(n1)-0.5))

The output voltage appears at node n2. The voltage at input node n1 must be between 0 and 1. Both nodes are ground-referenced.

def setup_comparator(self, f, ts, slopeGain, n1, n2, n3):

Constructs a smooth-edged comparator intended for use with a triangle wave on input n1 and a (relatively) constant voltage between 0 and 1 on input n2.

Specify the output rise/fall time by supplying a multiple of the triangle wave slope vs the output signal slope, slopeGain.

Input nodes n1 and n2 and output node n3 are all ground-referenced.

The zero-state output voltage is set by my Vlow attribute, and the one-state voltage by my Vhigh attribute.

def setup(self, f):

overrides pingspice.circuit.netlist.Subcircuit.setup

Defines the subcircuit netlist for a PWM oscillator with simulation-friendly transitions from Vlow to Vhigh and back again.

This is the output voltage expression, where X is a triangle wave from -0.5 to +0.5 and ctrl is an input node whose value can range from 0 (0% duty cycle) to 1.0 (100%):

V = b + m*tanh(tGain*(X + aGain*atanh((1/aGain-2/tGain)*(ctrl-0.5))))

API Documentation for pingspice, generated by pydoctor at 2021-09-18 08:41:11.

pingspice.lib.active.PWM(Subcircuit) class documentation

`pingspice.lib.active.PWM(Subcircuit)` class documentation