Spice reader enhancements

Basic goal is to align ngspice and KLayout Spice format comprehension. ".options scale" was implemented together with a number of other patches. Consistency has been confirmed with respect to these features and formula evaluation.
2023-03-12 15:36:50 +01:00 · 2023-03-12 15:36:50 +01:00 · db8f9d5bcb
parent 6955d7d0c7
commit db8f9d5bcb
11 changed files with 355 additions and 78 deletions
--- a/src/db/db/dbDeviceClass.h
+++ b/src/db/db/dbDeviceClass.h
@ -146,7 +146,7 @@ public:
   *  @brief Creates an empty device parameter definition
   */
  DeviceParameterDefinition ()
-    : m_name (), m_description (), m_default_value (0.0), m_id (0), m_is_primary (true), m_si_scaling (1.0)
+    : m_name (), m_description (), m_default_value (0.0), m_id (0), m_is_primary (true), m_si_scaling (1.0), m_geo_scaling (0.0)
  {
    //  .. nothing yet ..
  }
@ -154,8 +154,8 @@ public:
  /**
   *  @brief Creates a device parameter definition with the given name and description
   */
-  DeviceParameterDefinition (const std::string &name, const std::string &description, double default_value = 0.0, bool is_primary = true, double si_scaling = 1.0)
-    : m_name (name), m_description (description), m_default_value (default_value), m_id (0), m_is_primary (is_primary), m_si_scaling (si_scaling)
+  DeviceParameterDefinition (const std::string &name, const std::string &description, double default_value = 0.0, bool is_primary = true, double si_scaling = 1.0, double geo_scaling = 0.0)
+    : m_name (name), m_description (description), m_default_value (default_value), m_id (0), m_is_primary (is_primary), m_si_scaling (si_scaling), m_geo_scaling (geo_scaling)
  {
    //  .. nothing yet ..
  }
@ -192,18 +192,10 @@ public:
    m_description = d;
  }

-  /**
-   *  @brief Gets the parameter default value
-   */
-  double default_value () const
-  {
-    return m_default_value;
-  }
-
  /**
   *  @brief Gets the SI unit scaling factor
   *
-   *  Some parameters are given in micrometers for example. This
+   *  Some parameters are given in micrometers - for example W and L of MOS devices. This
   *  scaling factor gives the translation to SI units (1e-6 for micrometers).
   */
  double si_scaling () const
@ -212,7 +204,43 @@ public:
  }

  /**
-   *  @brief Sets the parameter description
+   *  @brief Set the SI unit scaling factor
+   */
+  void set_si_scaling (double s)
+  {
+    m_si_scaling = s;
+  }
+
+  /**
+   *  @brief Gets the geometry scaling exponent
+   *
+   *  The geometry scaling exponent is used for example when applying .option scale
+   *  in Spice reading. It is 0 for "no scaling", 1 for linear scaling and 2 for
+   *  quadratic scaling.
+   */
+  double geo_scaling_exponent () const
+  {
+    return m_geo_scaling;
+  }
+
+  /**
+   *  @brief Sets the geometry scaling exponent
+   */
+  void set_geo_scaling_exponent (double e)
+  {
+    m_geo_scaling = e;
+  }
+
+  /**
+   *  @brief Gets the parameter default value
+   */
+  double default_value () const
+  {
+    return m_default_value;
+  }
+
+  /**
+   *  @brief Sets the parameter default value
   */
  void set_default_value (double d)
  {
@ -267,6 +295,7 @@ private:
  size_t m_id;
  bool m_is_primary;
  double m_si_scaling;
+  double m_geo_scaling;

  void set_id (size_t id)
  {
--- a/src/db/db/dbNetlistDeviceClasses.cc
+++ b/src/db/db/dbNetlistDeviceClasses.cc
@ -487,10 +487,10 @@ DeviceClassResistor::DeviceClassResistor ()
  equivalent_terminal_id (terminal_id_A, terminal_id_B);

  add_parameter_definition (db::DeviceParameterDefinition ("R", "Resistance (Ohm)", 0.0));
-  add_parameter_definition (db::DeviceParameterDefinition ("L", "Length (micrometer)", 0.0, false, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("W", "Width (micrometer)", 0.0, false, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6));
+  add_parameter_definition (db::DeviceParameterDefinition ("L", "Length (micrometer)", 0.0, false, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("W", "Width (micrometer)", 0.0, false, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
 }

 // ------------------------------------------------------------------------------------
@ -526,8 +526,8 @@ DeviceClassCapacitor::DeviceClassCapacitor ()
  equivalent_terminal_id (terminal_id_A, terminal_id_B);

  add_parameter_definition (db::DeviceParameterDefinition ("C", "Capacitance (Farad)", 0.0));
-  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6));
+  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
 }

 // ------------------------------------------------------------------------------------
@ -580,8 +580,8 @@ DeviceClassDiode::DeviceClassDiode ()
  add_terminal_definition (db::DeviceTerminalDefinition ("A", "Anode"));
  add_terminal_definition (db::DeviceTerminalDefinition ("C", "Cathode"));

-  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6));
+  add_parameter_definition (db::DeviceParameterDefinition ("A", "Area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("P", "Perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
 }

 // ------------------------------------------------------------------------------------
@ -608,12 +608,12 @@ DeviceClassMOS3Transistor::DeviceClassMOS3Transistor ()
  add_terminal_definition (db::DeviceTerminalDefinition ("D", "Drain"));
  equivalent_terminal_id (terminal_id_D, terminal_id_S);

-  add_parameter_definition (db::DeviceParameterDefinition ("L", "Gate length (micrometer)", 0.0, true, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("W", "Gate width (micrometer)", 0.0, true, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("AS", "Source area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("AD", "Drain area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("PS", "Source perimeter (micrometer)", 0.0, false, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("PD", "Drain perimeter (micrometer)", 0.0, false, 1e-6));
+  add_parameter_definition (db::DeviceParameterDefinition ("L", "Gate length (micrometer)", 0.0, true, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("W", "Gate width (micrometer)", 0.0, true, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("AS", "Source area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("AD", "Drain area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("PS", "Source perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("PD", "Drain perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
 }

 bool
@ -886,12 +886,12 @@ DeviceClassBJT3Transistor::DeviceClassBJT3Transistor ()
  add_terminal_definition (db::DeviceTerminalDefinition ("E", "Emitter"));

  //  NOTE: the emitter area and the emitter count are the primary parameters
-  add_parameter_definition (db::DeviceParameterDefinition ("AE", "Emitter area (square micrometer)", 0.0, true, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("PE", "Emitter perimeter (micrometer)", 0.0, false, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("AB", "Base area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("PB", "Base perimeter (micrometer)", 0.0, false, 1e-6));
-  add_parameter_definition (db::DeviceParameterDefinition ("AC", "Collector area (square micrometer)", 0.0, false, 1e-12));
-  add_parameter_definition (db::DeviceParameterDefinition ("PC", "Collector perimeter (micrometer)", 0.0, false, 1e-6));
+  add_parameter_definition (db::DeviceParameterDefinition ("AE", "Emitter area (square micrometer)", 0.0, true, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("PE", "Emitter perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("AB", "Base area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("PB", "Base perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("AC", "Collector area (square micrometer)", 0.0, false, 1e-12, 2.0));
+  add_parameter_definition (db::DeviceParameterDefinition ("PC", "Collector perimeter (micrometer)", 0.0, false, 1e-6, 1.0));
  add_parameter_definition (db::DeviceParameterDefinition ("NE", "Emitter count", 1.0, true));
 }

--- a/src/db/db/dbNetlistSpiceReader.cc
+++ b/src/db/db/dbNetlistSpiceReader.cc
@ -388,6 +388,7 @@ private:
  void read_subcircuit (const std::string &sc_name, const std::string &nc_name, const std::vector<db::Net *> &nets);
  void read_circuit (tl::Extractor &ex, const std::string &name);
  bool read_card ();
+  void read_options (tl::Extractor &ex);
  void ensure_circuit ();
  std::string get_line ();
  void error (const std::string &msg);
@ -614,6 +615,10 @@ SpiceCircuitDict::read_card ()
    std::string nc = read_name (ex, mp_netlist);
    read_circuit (ex, nc);

+  } else if (ex.test_without_case (".options")) {
+
+    read_options (ex);
+
  } else if (ex.test_without_case (".ends")) {

    return true;
@ -680,6 +685,56 @@ SpiceCircuitDict::read_card ()
  return false;
 }

+void
+SpiceCircuitDict::read_options (tl::Extractor &ex)
+{
+  while (! ex.at_end ()) {
+
+    std::string n;
+    ex.read_word_or_quoted (n, allowed_name_chars);
+    n = tl::to_lower_case (n);
+
+    double v = 0.0;
+    std::string w;
+    if (ex.test ("=")) {
+      if (ex.try_read (v)) {
+        //  take value
+      } else {
+        //  skip until end or next space
+        ex.skip ();
+        while (! ex.at_end () && ! isspace (*ex)) {
+          ++ex;
+        }
+      }
+    }
+
+    //  TODO: further options?
+    const double min_value = 1e-18;
+    if (n == "scale") {
+      if (v > min_value) {
+        mp_delegate->options ().scale = v;
+      }
+    } else if (n == "defad") {
+      if (v > min_value) {
+        mp_delegate->options ().defad = v;
+      }
+    } else if (n == "defas") {
+      if (v > min_value) {
+        mp_delegate->options ().defas = v;
+      }
+    } else if (n == "defl") {
+      if (v > min_value) {
+        mp_delegate->options ().defl = v;
+      }
+    } else if (n == "defw") {
+      if (v > min_value) {
+        mp_delegate->options ().defw = v;
+      }
+    }
+
+  }
+}
+
 void
 SpiceCircuitDict::ensure_circuit ()
 {
--- a/src/db/db/dbNetlistSpiceReaderDelegate.cc
+++ b/src/db/db/dbNetlistSpiceReaderDelegate.cc
@ -86,6 +86,18 @@ static std::string unescape_name (const std::string &n)

 // ------------------------------------------------------------------------------------------------------

+NetlistSpiceReaderOptions::NetlistSpiceReaderOptions ()
+{
+  scale = 1.0;
+  defad = 0.0;
+  defas = 0.0;
+  //  ngspice defaults:
+  defw = 100e-6;
+  defl = 100e-6;
+}
+
+// ------------------------------------------------------------------------------------------------------
+
 NetlistSpiceReaderDelegate::NetlistSpiceReaderDelegate ()
  : mp_netlist (0)
 {
@ -107,7 +119,7 @@ void NetlistSpiceReaderDelegate::finish (db::Netlist * /*netlist*/)
  //  .. nothing yet ..
 }

-bool NetlistSpiceReaderDelegate::control_statement(const std::string & /*line*/)
+bool NetlistSpiceReaderDelegate::control_statement (const std::string & /*line*/)
 {
  return false;
 }
@ -196,7 +208,8 @@ void NetlistSpiceReaderDelegate::parse_element_components (const std::string &s,
      if (ex.try_read_word (n) && ex.test ("=")) {

        //  a parameter
-        pv [mp_netlist ? mp_netlist->normalize_name (n) : tl::to_upper_case (n)] = read_value (ex, variables);
+        std::string pn = mp_netlist ? mp_netlist->normalize_name (n) : tl::to_upper_case (n);
+        pv [pn] = read_value (ex, variables);

      } else {

@ -231,8 +244,21 @@ void NetlistSpiceReaderDelegate::parse_element_components (const std::string &s,
  }
 }

+void NetlistSpiceReaderDelegate::def_values_per_element (const std::string &element, std::map<std::string, tl::Variant> &pv)
+{
+  if (element == "M") {
+
+    pv.insert (std::make_pair ("W", m_options.defw));
+    pv.insert (std::make_pair ("L", m_options.defl));
+    pv.insert (std::make_pair ("AD", m_options.defad));
+    pv.insert (std::make_pair ("AS", m_options.defas));
+
+  }
+}
+
 void NetlistSpiceReaderDelegate::parse_element (const std::string &s, const std::string &element, std::string &model, double &value, std::vector<std::string> &nn, std::map<std::string, tl::Variant> &pv, const std::map<std::string, tl::Variant> &variables)
 {
+  def_values_per_element (element, pv);
  parse_element_components (s, nn, pv, variables);

  //  interpret the parameters according to the code
@ -337,6 +363,8 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
  std::map<std::string, tl::Variant> params = pv;
  std::vector<size_t> terminal_order;

+  size_t defp = std::numeric_limits<size_t>::max ();
+
  double mult = 1.0;
  auto mp = params.find ("M");
  if (mp != params.end ()) {
@ -378,9 +406,20 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
      error (tl::to_string (tr ("A 'R' element requires two or three nets")));
    }

-    //  Apply multiplier
+    //  Apply multiplier (divider, according to ngspice manual)
    value /= mult;

+    defp = db::DeviceClassResistor::param_id_R;
+
+    //  Apply multiplier to other parameters
+    static const char *scale_params[] = { "A", "P", "W" };
+    for (size_t i = 0; i < sizeof (scale_params) / sizeof (scale_params[0]); ++i) {
+      auto p = params.find (scale_params [i]);
+      if (p != params.end ()) {
+        p->second = tl::Variant (p->second.to_double () * mult);
+      }
+    }
+
  } else if (element == "L") {

    if (nets.size () == 2) {
@ -398,9 +437,11 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
      error (tl::to_string (tr ("A 'L' element requires two nets")));
    }

-    //  Apply multiplier
+    //  Apply multiplier (divider, according to ngspice manual)
    value /= mult;

+    defp = db::DeviceClassInductor::param_id_L;
+
  } else if (element == "C") {

    if (nets.size () == 2) {
@ -432,6 +473,17 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
    //  Apply multiplier
    value *= mult;

+    defp = db::DeviceClassCapacitor::param_id_C;
+
+    //  Apply multiplier to other parameters
+    static const char *scale_params[] = { "A", "P" };
+    for (size_t i = 0; i < sizeof (scale_params) / sizeof (scale_params[0]); ++i) {
+      auto p = params.find (scale_params [i]);
+      if (p != params.end ()) {
+        p->second = tl::Variant (p->second.to_double () * mult);
+      }
+    }
+
  } else if (element == "D") {

    if (cls) {
@ -445,10 +497,13 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
      cls = make_device_class<db::DeviceClassDiode> (circuit, cn);
    }

-    //  Apply multiplier to "A"
-    auto p = params.find ("A");
-    if (p != params.end ()) {
-      p->second = tl::Variant (p->second.to_double () * mult);
+    //  Apply multiplier
+    static const char *scale_params[] = { "A", "P" };
+    for (size_t i = 0; i < sizeof (scale_params) / sizeof (scale_params[0]); ++i) {
+      auto p = params.find (scale_params [i]);
+      if (p != params.end ()) {
+        p->second = tl::Variant (p->second.to_double () * mult);
+      }
    }

  } else if (element == "Q") {
@ -479,10 +534,13 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
      }
    }

-    //  Apply multiplier to "AE"
-    auto p = params.find ("AE");
-    if (p != params.end ()) {
-      p->second = tl::Variant (p->second.to_double () * mult);
+    //  Apply multiplier
+    static const char *scale_params[] = { "AE", "PE", "AB", "PB", "AC", "PC" };
+    for (size_t i = 0; i < sizeof (scale_params) / sizeof (scale_params[0]); ++i) {
+      auto p = params.find (scale_params [i]);
+      if (p != params.end ()) {
+        p->second = tl::Variant (p->second.to_double () * mult);
+      }
    }

  } else if (element == "M") {
@ -502,10 +560,13 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
      }
    }

-    //  Apply multiplier to "W"
-    auto p = params.find ("W");
-    if (p != params.end ()) {
-      p->second = tl::Variant (p->second.to_double () * mult);
+    //  Apply multiplier
+    static const char *scale_params[] = { "W", "AD", "AS", "PD", "PS" };
+    for (size_t i = 0; i < sizeof (scale_params) / sizeof (scale_params[0]); ++i) {
+      auto p = params.find (scale_params [i]);
+      if (p != params.end ()) {
+        p->second = tl::Variant (p->second.to_double () * mult);
+      }
    }

    //  issue #1304
@ -537,23 +598,18 @@ bool NetlistSpiceReaderDelegate::element (db::Circuit *circuit, const std::strin
  }


-  size_t defp = std::numeric_limits<size_t>::max ();
-  if (dynamic_cast<db::DeviceClassCapacitor *> (cls)) {
-    defp = db::DeviceClassCapacitor::param_id_C;
-  } else if (dynamic_cast<db::DeviceClassResistor *> (cls)) {
-    defp = db::DeviceClassResistor::param_id_R;
-  } else if (dynamic_cast<db::DeviceClassInductor *> (cls)) {
-    defp = db::DeviceClassInductor::param_id_L;
-  }
-
  std::vector<db::DeviceParameterDefinition> &pd = cls->parameter_definitions_non_const ();
  for (std::vector<db::DeviceParameterDefinition>::iterator i = pd.begin (); i != pd.end (); ++i) {
    auto v = params.find (i->name ());
+    double pv = 0.0;
    if (v != params.end ()) {
-      device->set_parameter_value (i->id (), v->second.to_double () / i->si_scaling ());
+      pv = v->second.to_double ();
    } else if (i->id () == defp) {
-      device->set_parameter_value (i->id (), value / i->si_scaling ());
+      pv = value;
+    } else {
+      continue;
    }
+    device->set_parameter_value (i->id (), pv / i->si_scaling () * pow (m_options.scale, i->geo_scaling_exponent ()));
  }

  return true;
--- a/src/db/db/dbNetlistSpiceReaderDelegate.h
+++ b/src/db/db/dbNetlistSpiceReaderDelegate.h
@ -40,6 +40,14 @@ class Circuit;
 class DeviceClass;
 class Device;

+struct DB_PUBLIC NetlistSpiceReaderOptions
+{
+  NetlistSpiceReaderOptions ();
+
+  double scale;
+  double defad, defas, defw, defl;
+};
+
 /**
 *  @brief A delegate to handle various forms of devices and translates them
 *
@ -55,6 +63,22 @@ public:
  NetlistSpiceReaderDelegate ();
  virtual ~NetlistSpiceReaderDelegate ();

+  /**
+   *  @brief Gets the reader options
+   */
+  NetlistSpiceReaderOptions &options ()
+  {
+    return m_options;
+  }
+
+  /**
+   *  @brief Gets the reader options
+   */
+  const NetlistSpiceReaderOptions &options () const
+  {
+    return m_options;
+  }
+
  /**
   *  @brief Called when the netlist reading starts
   */
@ -122,7 +146,6 @@ public:

  /**
   *  @brief Reads a set of string components and parameters from the string
-   *  A special key "param:" is recognized for starting a parameter list.
   */
  void parse_element_components (const std::string &s, std::vector<std::string> &strings, std::map<std::string, tl::Variant> &pv, const std::map<std::string, tl::Variant> &variables);

@ -162,6 +185,9 @@ public:

 private:
  db::Netlist *mp_netlist;
+  NetlistSpiceReaderOptions m_options;
+
+  void def_values_per_element (const std::string &element, std::map<std::string, tl::Variant> &pv);
 };

 }
--- a/src/db/db/dbNetlistSpiceReaderExpressionParser.cc
+++ b/src/db/db/dbNetlistSpiceReaderExpressionParser.cc
@ -44,7 +44,8 @@ static bool to_bool (const tl::Variant &v)
 }
 // ------------------------------------------------------------------------------------------------------

-NetlistSpiceReaderExpressionParser::NetlistSpiceReaderExpressionParser (const variables_type *vars)
+NetlistSpiceReaderExpressionParser::NetlistSpiceReaderExpressionParser (const variables_type *vars, double def_scale)
+  : m_def_scale (def_scale)
 {
  static variables_type empty_variables;
  mp_variables = vars ? vars : &empty_variables;
@ -202,7 +203,7 @@ NetlistSpiceReaderExpressionParser::read_atomic_value (tl::Extractor &ex, bool *
      *status = true;
    }

-    double f = 1.0;
+    double f = m_def_scale;
    if (*ex == 't' || *ex == 'T') {
      f = 1e12;
    } else if (*ex == 'g' || *ex == 'G') {
--- a/src/db/db/dbNetlistSpiceReaderExpressionParser.h
+++ b/src/db/db/dbNetlistSpiceReaderExpressionParser.h
@ -45,7 +45,7 @@ class DB_PUBLIC NetlistSpiceReaderExpressionParser
 public:
  typedef std::map<std::string, tl::Variant> variables_type;

-  NetlistSpiceReaderExpressionParser (const variables_type *vars);
+  NetlistSpiceReaderExpressionParser (const variables_type *vars, double def_scale = 1.0);

  tl::Variant read (tl::Extractor &ex) const;
  tl::Variant read (const std::string &s) const;
@ -54,6 +54,7 @@ public:

 private:
  const variables_type *mp_variables;
+  double m_def_scale;

  tl::Variant read_atomic_value (tl::Extractor &ex, bool *status) const;
  tl::Variant read_dot_expr (tl::Extractor &ex, bool *status) const;
--- a/src/db/db/gsiDeclDbNetlist.cc
+++ b/src/db/db/gsiDeclDbNetlist.cc
@ -790,19 +790,20 @@ Class<db::DeviceTerminalDefinition> decl_dbDeviceTerminalDefinition ("db", "Devi
  "This class has been added in version 0.26."
 );

-static db::DeviceParameterDefinition *new_parameter_definition (const std::string &name, const std::string &description, double default_value, bool is_primary, double si_scaling)
+static db::DeviceParameterDefinition *new_parameter_definition (const std::string &name, const std::string &description, double default_value, bool is_primary, double si_scaling, double geo_scaling_exponent)
 {
-  return new db::DeviceParameterDefinition (name, description, default_value, is_primary, si_scaling);
+  return new db::DeviceParameterDefinition (name, description, default_value, is_primary, si_scaling, geo_scaling_exponent);
 }

 Class<db::DeviceParameterDefinition> decl_dbDeviceParameterDefinition ("db", "DeviceParameterDefinition",
-  gsi::constructor ("new", &gsi::new_parameter_definition, gsi::arg ("name"), gsi::arg ("description", std::string ()), gsi::arg ("default_value", 0.0), gsi::arg ("is_primary", true), gsi::arg ("si_scaling", 1.0),
+  gsi::constructor ("new", &gsi::new_parameter_definition, gsi::arg ("name"), gsi::arg ("description", std::string ()), gsi::arg ("default_value", 0.0), gsi::arg ("is_primary", true), gsi::arg ("si_scaling", 1.0), gsi::arg ("geo_scaling_exponent", 0.0),
    "@brief Creates a new parameter definition.\n"
    "@param name The name of the parameter\n"
    "@param description The human-readable description\n"
    "@param default_value The initial value\n"
    "@param is_primary True, if the parameter is a primary parameter (see \\is_primary=)\n"
    "@param si_scaling The scaling factor to SI units\n"
+    "@param geo_scaling_exponent Indicates how the parameter scales with geometrical scaling (0: no scaling, 1.0: linear, 2.0: quadratic)\n"
  ) +
  gsi::method ("name", &db::DeviceParameterDefinition::name,
    "@brief Gets the name of the parameter."
@ -834,7 +835,26 @@ Class<db::DeviceParameterDefinition> decl_dbDeviceParameterDefinition ("db", "De
  ) +
  gsi::method ("si_scaling", &db::DeviceParameterDefinition::si_scaling,
    "@brief Gets the scaling factor to SI units.\n"
-    "For parameters in micrometers for example, this factor will be 1e-6."
+    "For parameters in micrometers - for example W and L of MOS devices - this factor can be set to 1e-6 to reflect "
+    "the unit."
+  ) +
+  gsi::method ("si_scaling=", &db::DeviceParameterDefinition::set_si_scaling,
+    "@brief Sets the scaling factor to SI units.\n"
+    "\n"
+    "This setter has been added in version 0.28.6."
+  ) +
+  gsi::method ("geo_scaling_exponent", &db::DeviceParameterDefinition::geo_scaling_exponent,
+    "@brief Gets the geometry scaling exponent.\n"
+    "This value is used when applying '.options scale' in the SPICE reader for example. "
+    "It is zero for 'no scaling', 1.0 for linear scaling and 2.0 for quadratic scaling.\n"
+    "\n"
+    "This attribute has been added in version 0.28.6."
+  ) +
+  gsi::method ("geo_scaling_exponent=", &db::DeviceParameterDefinition::set_geo_scaling_exponent,
+    "@brief Sets the geometry scaling exponent.\n"
+    "See \\geo_scaling_exponent for details.\n"
+    "\n"
+    "This attribute has been added in version 0.28.6."
  ) +
  gsi::method ("id", &db::DeviceParameterDefinition::id,
    "@brief Gets the ID of the parameter.\n"
--- a/src/db/unit_tests/dbNetlistReaderTests.cc
+++ b/src/db/unit_tests/dbNetlistReaderTests.cc
@ -704,16 +704,50 @@ TEST(18_XSchemOutput)
    "  subcircuit 'PMOS4_STANDARD(L=0.15U,NF=2,W=1.5U)' XDUMMY3 (D=VDD,G=VDD,S=VDD,B=VDD);\n"
    "end;\n"
    "circuit 'PMOS4_STANDARD(L=0.15U,NF=4,W=1.5U)' (D=D,G=G,S=S,B=B);\n"
-    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=0.32625,AD=0.2175,PS=2.685,PD=1.79);\n"
+    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=1.305,AD=0.87,PS=10.74,PD=7.16);\n"
    "end;\n"
    "circuit 'NMOS4_STANDARD(L=0.15U,NF=4,W=1.5U)' (D=D,G=G,S=S,B=B);\n"
-    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=0.32625,AD=0.2175,PS=2.685,PD=1.79);\n"
+    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=1.305,AD=0.87,PS=10.74,PD=7.16);\n"
    "end;\n"
    "circuit 'NMOS4_STANDARD(L=0.15U,NF=2,W=1.5U)' (D=D,G=G,S=S,B=B);\n"
-    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.435,AD=0.2175,PS=3.58,PD=1.79);\n"
+    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.87,AD=0.435,PS=7.16,PD=3.58);\n"
    "end;\n"
    "circuit 'PMOS4_STANDARD(L=0.15U,NF=2,W=1.5U)' (D=D,G=G,S=S,B=B);\n"
-    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.435,AD=0.2175,PS=3.58,PD=1.79);\n"
+    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.87,AD=0.435,PS=7.16,PD=3.58);\n"
+    "end;\n"
+  );
+}
+
+TEST(19_ngspice_ref)
+{
+  db::Netlist nl;
+
+  std::string path = tl::combine_path (tl::combine_path (tl::testdata (), "algo"), "nreader19.cir");
+
+  db::NetlistSpiceReader reader;
+  tl::InputStream is (path);
+  reader.read (is, nl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit .TOP ();\n"
+    "  subcircuit 'PMOS4_STANDARD(L=0.15,NF=4,W=1.5)' XPMOS (D=Q,G=I,S=VDD,B=VDD);\n"
+    "  subcircuit 'NMOS4_STANDARD(L=0.15,NF=4,W=1.5)' XNMOS (D=Q,G=I,S=VSS,B=VSS);\n"
+    "  subcircuit 'NMOS4_STANDARD(L=0.15,NF=2,W=1.5)' XDUMMY0 (D=VSS,G=VSS,S=VSS,B=VSS);\n"
+    "  subcircuit 'NMOS4_STANDARD(L=0.15,NF=2,W=1.5)' XDUMMY1 (D=VSS,G=VSS,S=VSS,B=VSS);\n"
+    "  subcircuit 'PMOS4_STANDARD(L=0.15,NF=2,W=1.5)' XDUMMY2 (D=VDD,G=VDD,S=VDD,B=VDD);\n"
+    "  subcircuit 'PMOS4_STANDARD(L=0.15,NF=2,W=1.5)' XDUMMY3 (D=VDD,G=VDD,S=VDD,B=VDD);\n"
+    "end;\n"
+    "circuit 'PMOS4_STANDARD(L=0.15,NF=4,W=1.5)' (D=D,G=G,S=S,B=B);\n"
+    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=0.32625,AD=0.2175,PS=3.99,PD=2.66);\n"
+    "end;\n"
+    "circuit 'NMOS4_STANDARD(L=0.15,NF=4,W=1.5)' (D=D,G=G,S=S,B=B);\n"
+    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=6,AS=0.32625,AD=0.2175,PS=3.99,PD=2.66);\n"
+    "end;\n"
+    "circuit 'NMOS4_STANDARD(L=0.15,NF=2,W=1.5)' (D=D,G=G,S=S,B=B);\n"
+    "  device SKY130_FD_PR__NFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.435,AD=0.2175,PS=4.16,PD=2.08);\n"
+    "end;\n"
+    "circuit 'PMOS4_STANDARD(L=0.15,NF=2,W=1.5)' (D=D,G=G,S=S,B=B);\n"
+    "  device SKY130_FD_PR__PFET_01V8 M1 (S=S,G=G,D=D,B=B) (L=0.15,W=3,AS=0.435,AD=0.2175,PS=4.16,PD=2.08);\n"
    "end;\n"
  );
 }
@ -828,3 +862,18 @@ TEST(100_ExpressionParser)
  EXPECT_EQ (parser.try_read ("\"1+2*(2+1)-1\"", v), true);
  EXPECT_EQ (v.to_string (), "6");
 }
+
+TEST(101_ExpressionParserWithDefScale)
+{
+  std::map<std::string, tl::Variant> vars;
+  vars["A"] = 17.5;
+
+  tl::Variant v;
+
+  db::NetlistSpiceReaderExpressionParser parser (&vars, 1e-3);
+
+  EXPECT_EQ (parser.read ("1.75").to_string (), "0.00175");
+  EXPECT_EQ (parser.read ("-1.75u").to_string (), "-1.75e-06");
+  EXPECT_EQ (parser.read ("1.75k").to_string (), "1750");
+  EXPECT_EQ (parser.read ("2*A").to_string (), "0.035");
+}
--- a/testdata/algo/nreader19.cir
+++ b/testdata/algo/nreader19.cir
@ -0,0 +1,27 @@
+* Test
+
+.options scale=1e-6
+
+.model sky130_fd_pr__pfet_01v8 NMOS level=8 version=3.3.0
+.model sky130_fd_pr__nfet_01v8 NMOS level=8 version=3.3.0
+
+XXpmos Q I VDD VDD pmos4_standard w=1.5 l=0.15 nf=4
+XXnmos Q I VSS VSS nmos4_standard w=1.5 l=0.15 nf=4
+XXDUMMY0 VSS VSS VSS VSS nmos4_standard w=1.5 l=0.15 nf=2
+XXDUMMY1 VSS VSS VSS VSS nmos4_standard w=1.5 l=0.15 nf=2
+XXDUMMY2 VDD VDD VDD VDD pmos4_standard w=1.5 l=0.15 nf=2
+XXDUMMY3 VDD VDD VDD VDD pmos4_standard w=1.5 l=0.15 nf=2
+
+.subckt pmos4_standard  D G S B  w=0.1  l=0.018  nf=4
+MM1 D G S B sky130_fd_pr__pfet_01v8 L=l W='w * nf ' ad='int((nf+1)/2) * W/nf * 0.29' as='int((nf+2)/2) * W/nf * 0.29'
+ pd='2*int((nf+1)/2) * (W/nf + 0.29)' ps='2*int((nf+2)/2) * (W/nf + 0.29)' nrd='0.29 / W' nrs='0.29 / W'
+ m=1
+.ends
+
+.subckt nmos4_standard  D G S B  w=0.1  l=0.018  nf=4
+MM1 D G S B sky130_fd_pr__nfet_01v8 L=l W='w * nf ' ad='int((nf+1)/2) * W/nf * 0.29' as='int((nf+2)/2) * W/nf * 0.29'
+ pd='2*int((nf+1)/2) * (W/nf + 0.29)' ps='2*int((nf+2)/2) * (W/nf + 0.29)' nrd='0.29 / W' nrs='0.29 / W'
+ m=1
+.ends
+
+.end
--- a/testdata/ruby/dbNetlist.rb
+++ b/testdata/ruby/dbNetlist.rb
@ -625,14 +625,9 @@ class DBNetlist_TestClass < TestBase
    dc.terminal_definitions.each { |pd| names << pd.name }
    assert_equal(names, [])

-    pd = RBA::DeviceParameterDefinition::new("P1", "Parameter 1", 2.0)
-    assert_equal(pd.default_value, 2.0)
+    pd = RBA::DeviceParameterDefinition::new("P1", "Parameter 1")
    pd.default_value = 1.0
-    assert_equal(pd.default_value, 1.0)
-    pd.is_primary = false
-    assert_equal(pd.is_primary?, false)
    pd.is_primary = true
-    assert_equal(pd.is_primary?, true)

    dc.add_parameter(pd)

@ -1181,6 +1176,24 @@ END

  end

+  def test_16_deviceParameterObject
+
+    pd = RBA::DeviceParameterDefinition::new("P1", "Parameter 1", 2.0, false, 17.5, 2.0)
+    assert_equal(pd.default_value, 2.0)
+    pd.default_value = 1.0
+    assert_equal(pd.default_value, 1.0)
+    assert_equal(pd.is_primary?, false)
+    pd.is_primary = true
+    assert_equal(pd.is_primary?, true)
+    assert_equal(pd.si_scaling, 17.5)
+    pd.si_scaling = 1.0
+    assert_equal(pd.si_scaling, 1.0)
+    assert_equal(pd.geo_scaling_exponent, 2.0)
+    pd.geo_scaling_exponent = 1.0
+    assert_equal(pd.geo_scaling_exponent, 1.0)
+
+  end
+
 end

 load("test_epilogue.rb")