Classes
struct	Line
struct	Pair
struct	Solved

Enumerations
enum class	Structure : std::uint8_t { Microstrip , Stripline , Gcpw }

Functions
Line	microstrip (Coord w, Coord h, Coord t, double er)
	Microstrip: strip of width w and thickness t on a dielectric of height h (strip bottom to plane), εr er.
Line	stripline (Coord w, Coord h1, Coord h2, Coord t, double er)
	Stripline between two planes: h1 dielectric from the upper plane to the strip, h2 from the strip to the lower plane (the plane spacing is h1 + t + h2); symmetric when h1 == h2.
Pair	coupled_microstrip (Coord w, Coord s, Coord h, Coord t, double er)
	Edge-coupled microstrip: two strips of width w, edge-to-edge gap s.
Pair	coupled_stripline (Coord w, Coord s, Coord h1, Coord h2, Coord t, double er)
	Edge-coupled stripline (broadside layout not modelled).
Line	gcpw (Coord w, Coord g, Coord h, Coord t, double er)
	Grounded (conductor-backed) coplanar waveguide: strip w, gap g to the coplanar ground on both sides, plane at h.
double	ipc2141_microstrip (Coord w, Coord h, Coord t, double er)
	IPC-2141A's simple forms (the industry rule of thumb, ±5-10 %), used only as an independent cross-check.
double	ipc2141_stripline (Coord w, Coord b, Coord t, double er)
	b = plane spacing, strip centred
double	prop_delay_ps_per_mm (double eps_eff)
	Propagation delay in ps/mm for an effective permittivity: sqrt(eps_eff) / c.
double	k_ratio (double k)
	Complete elliptic integral ratio K(k) / K(k'), k' = sqrt(1 - k^2), by the arithmetic-geometric mean (K(k) = pi / (2 AGM(1, k'))).
Solved	solve_monotone (const std::function< double(Coord)> &z_of, double target, Coord lo, Coord hi, bool decreasing)
	Bisection on integer nm for a function that decreases (decreasing = true, e.g.
const char *	structure_name (Structure s)
double	formula_error_pct (Structure s, bool differential, bool asymmetric)
	Formula error stated in the report, percent (doc 15 §5.3 point 3; dev/assumptions-m13.md).
Coord	width_for_current (double amps, double delta_t_c, Coord copper, bool external)
	IPC-2221B §6.2 (from the IPC-D-275 charts): I = k * dT^0.44 * A^0.725, A cross-section in mil^2, k = 0.048 external / 0.024 internal layers.
double	current_for_width (Coord width, double delta_t_c, Coord copper, bool external)

Variables
constexpr double	kEta0 = 376.730313668
	free-space wave impedance, ohm
constexpr double	kC0MmPerPs = 0.299792458
	speed of light, mm/ps

Enumeration Type Documentation

◆ Structure

enum class tmk::crules::imp::Structure : std::uint8_t

strong

Enumerator
Microstrip
Stripline
Gcpw

Definition at line 77 of file impedance.hpp.

Function Documentation

◆ coupled_microstrip()

Pair tmk::crules::imp::coupled_microstrip	(	Coord	w,
		Coord	s,
		Coord	h,
		Coord	t,
		double	er )

Edge-coupled microstrip: two strips of width w, edge-to-edge gap s.

◆ coupled_stripline()

Pair tmk::crules::imp::coupled_stripline	(	Coord	w,
		Coord	s,
		Coord	h1,
		Coord	h2,
		Coord	t,
		double	er )

Edge-coupled stripline (broadside layout not modelled).

◆ current_for_width()

double tmk::crules::imp::current_for_width	(	Coord	width,
		double	delta_t_c,
		Coord	copper,
		bool	external )

◆ formula_error_pct()

double tmk::crules::imp::formula_error_pct	(	Structure	s,
		bool	differential,
		bool	asymmetric )

Formula error stated in the report, percent (doc 15 §5.3 point 3; dev/assumptions-m13.md).

◆ gcpw()

Line tmk::crules::imp::gcpw	(	Coord	w,
		Coord	g,
		Coord	h,
		Coord	t,
		double	er )

Grounded (conductor-backed) coplanar waveguide: strip w, gap g to the coplanar ground on both sides, plane at h.

◆ ipc2141_microstrip()

double tmk::crules::imp::ipc2141_microstrip	(	Coord	w,
		Coord	h,
		Coord	t,
		double	er )

IPC-2141A's simple forms (the industry rule of thumb, ±5-10 %), used only as an independent cross-check.

◆ ipc2141_stripline()

double tmk::crules::imp::ipc2141_stripline	(	Coord	w,
		Coord	b,
		Coord	t,
		double	er )

b = plane spacing, strip centred

◆ k_ratio()

double tmk::crules::imp::k_ratio ( double k )

Complete elliptic integral ratio K(k) / K(k'), k' = sqrt(1 - k^2), by the arithmetic-geometric mean (K(k) = pi / (2 AGM(1, k'))).

Exposed for tests.

◆ microstrip()

Line tmk::crules::imp::microstrip	(	Coord	w,
		Coord	h,
		Coord	t,
		double	er )

Microstrip: strip of width w and thickness t on a dielectric of height h (strip bottom to plane), εr er.

◆ prop_delay_ps_per_mm()

double tmk::crules::imp::prop_delay_ps_per_mm ( double eps_eff )

Propagation delay in ps/mm for an effective permittivity: sqrt(eps_eff) / c.

◆ solve_monotone()

Solved tmk::crules::imp::solve_monotone	(	const std::function< double(Coord)> &	z_of,
		double	target,
		Coord	lo,
		Coord	hi,
		bool	decreasing )

Bisection on integer nm for a function that decreases (decreasing = true, e.g.

Z(width)) or increases (Z(gap)) monotonically on [lo, hi]. Returns the integer closest to the crossing (ties: the smaller value).

◆ stripline()

Line tmk::crules::imp::stripline	(	Coord	w,
		Coord	h1,
		Coord	h2,
		Coord	t,
		double	er )

Stripline between two planes: h1 dielectric from the upper plane to the strip, h2 from the strip to the lower plane (the plane spacing is h1 + t + h2); symmetric when h1 == h2.

Homogeneous dielectric: eps_eff = er.

◆ structure_name()

const char * tmk::crules::imp::structure_name ( Structure s )

◆ width_for_current()

Coord tmk::crules::imp::width_for_current	(	double	amps,
		double	delta_t_c,
		Coord	copper,
		bool	external )

IPC-2221B §6.2 (from the IPC-D-275 charts): I = k * dT^0.44 * A^0.725, A cross-section in mil^2, k = 0.048 external / 0.024 internal layers.

Width for amps at temperature rise delta_t_c with copper thickness copper (nm), rounded up to the next nm.

Variable Documentation

◆ kC0MmPerPs

double tmk::crules::imp::kC0MmPerPs = 0.299792458

inlineconstexpr

speed of light, mm/ps

Definition at line 26 of file impedance.hpp.

◆ kEta0

double tmk::crules::imp::kEta0 = 376.730313668