This branch is based on the master branch as of Juli 19th, 2026
Selected patches from https://github.com/javaNoviceProgrammer/Ngspice_OpenVAF_Enhancements/tree/main have been added,
some have been slightly modified, compatibility with VS 2022 is achieved.

PSS, HB, and reading, converting and using S parameters have been tested on a few examples.
Documentaion and further testing are due, as well as finally adding suitable commit messages.

The following commands have been taken from the docs at https://github.com/javaNoviceProgrammer/Ngspice_OpenVAF_Enhancements/blob/main/docs/Ngspice-OpenVAF-Handbook.pdf

Commands available in https://sourceforge.net/p/ngspice/ngspice/ci/hv_rf_preliminary/tree/:

Writing two-port or multi(N)-port S parameters
spar_write() (2-port) or spar_write_np() (N-port)

Periodic steady state (PSS)
pss <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff> 

Periodic AC (PAC)
pac <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff>  <DEC/OCT/LIN> <Npoints> <fstart> <fstop>

PNOISE
pnoise <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff> <Outnode> <InSrc> <DEC/OCT/LIN> <Npoints> <fstart> <fstop>

Periodic transfer function (PXF)
pxf <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff> <Outnode> <InSrc> <DEC/OCT/LIN> <Npoints> <fstart> <fstop> [max sideband]

Cyclostationary noise
pnoise <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff> <Outnode> <InSrc> <DEC/OCT/LIN> <Npoints> <fstart> <fstop> cyclo

Periodic S parameters
psp <Fguess> <StabTime> <OscNoB> <Points> <Harmonics> <Sc_iter> <Steady_Coeff> <Outnode> <InSrc> <DEC/OCT/LIN> <Npoints> <fstart> <fstop> [max sideband]

Quasi-periodic two-tone steady state (QPSS)
qpss <expr> <f1> <f2> [periods] [max order]
     | e.g. V(out)

Harmonic Balance (HB)
hb <Fguess> <Harmonics> [points] [maxiter]

Two-tone HB (frequency domain QPSS)
qpss <expr> <f1> <f2> hb <k1> <k2>

Two-tone small-signal QPAC (quasi periodic AC)
qpss <expr> <f1> <f2> hb <k1> <k2>
qpac <f_in>

Two-tone small-signal Qnoise (quasi periodic noise)
qpss <expr> <f1> <f2> hb <k1> <k2>
qnoise <output node> <f_in>

Cyclo stationary QPNOISE
qnoise <output node> <f_in> cyclo

Oscillator phase noise (autonomous HB plus phase noise)
hbosc <oscnode> <K> [fguess] [tstab]
phasenoise <fstart> <fstop> [points]

Two-tone small-signal quasi-periodic transfer function QPXF
qpss <expr> <f1> <f2> hb <k1> <k2>
qpxf <output node> <f_in>

QPAC, QPnoise, and QPXF may be swept over frequency instead of fixed f_in, e.g.
replace 'qpxf <output node> <f_in>' by 'qpxf <output node> <dec/oct/lin> <Npo> <fstart> <fstop>'

Read S parameters and convert to instance with ports p1 to pN, referenced to ref.
Command in the .control section:
pre_snp -native my_touchstone.s2p ; reads a Touchstone file, vector fits and issues a *.nport file
Instance in the netlist
N1 p1 p2 ... pN ref mymodel
.model mymodel nport(file=my_touchstone.nport)

RF two-port stability
sp ... (generate the S parameters)
stab

load pull
loadpull -load <R> <L> <C> -out <node> -drive <Vsrc> -f <f0> [-supply <Vsrc>]