diff --git a/src/db/db/dbNetlistDeviceExtractorClasses.cc b/src/db/db/dbNetlistDeviceExtractorClasses.cc
index 20215b670..e6e3afbb7 100644
--- a/src/db/db/dbNetlistDeviceExtractorClasses.cc
+++ b/src/db/db/dbNetlistDeviceExtractorClasses.cc
@@ -144,22 +144,39 @@ void NetlistDeviceExtractorMOS3Transistor::extract_devices (const std::vector<db
           continue;
         }
 
-        db::Edges edges (rgate.edges () & rdiff2gate.edges ());
-        if (edges.size () != 2) {
-          error (tl::sprintf (tl::to_string (tr ("Expected two edges interacting gate/diff (found %d) - width and length may be incorrect")), int (edges.size ())), *p);
+        std::vector<db::Edges::length_type> widths;
+        for (db::Region::const_iterator d2g = rdiff2gate.begin (); ! d2g.at_end (); ++d2g) {
+
+          db::Region rd2g;
+          rd2g.insert (*d2g);
+
+          db::Edges edges (rgate.edges () & rd2g.edges ());
+          db::Edges::length_type l = edges.length ();
+          if (l == 0) {
+            error (tl::to_string (tr ("Vanishing edges for interaction gate/diff (corner interaction) - gate shape ignored")));
+          } else {
+            widths.push_back (l);
+          }
+
+        }
+
+        if (widths.size () != 2) {
           continue;
         }
 
-        if (! p->is_box ()) {
-          error (tl::to_string (tr ("Gate shape is not a box - width and length may be incorrect")), *p);
-        }
+        //  Computation of the gate length and width - this scheme is compatible with
+        //  non-rectangular gates and circular gates. The computation is based on the
+        //  relationship: A(gate) = L(gate) * W(gate). W(gate) is determined from the
+        //  accumulated edge lengths (average of left and right length).
+        double param_w = sdbu () * (widths[0] + widths[1]) * 0.5;
+        double param_l = sdbu () * sdbu () * double (rgate.area ()) / param_w;
 
         db::Device *device = create_device ();
 
         device->set_trans (db::DCplxTrans ((p->box ().center () - db::Point ()) * dbu ()));
 
-        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_W, sdbu () * edges.length () * 0.5);
-        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_L, sdbu () * (p->perimeter () - edges.length ()) * 0.5);
+        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_W, param_w);
+        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_L, param_l);
 
         int diff_index = 0;
         for (db::Region::const_iterator d = rdiff2gate.begin (); !d.at_end () && diff_index < 2; ++d, ++diff_index) {
@@ -230,24 +247,39 @@ void NetlistDeviceExtractorMOS3Transistor::extract_devices (const std::vector<db
           continue;
         }
 
-        db::Region diff2gate = sdiff2gate + ddiff2gate;
+        db::Edges::length_type sdwidth = 0, ddwidth = 0;
 
-        db::Edges edges (rgate.edges () & diff2gate.edges ());
-        if (edges.size () != 2) {
-          error (tl::sprintf (tl::to_string (tr ("Expected two edges interacting gate/diff (found %d) - width and length may be incorrect")), int (edges.size ())), *p);
-          continue;
+        {
+          db::Edges edges (rgate.edges () & sdiff2gate.edges ());
+          sdwidth = edges.length ();
+          if (sdwidth == 0) {
+            error (tl::to_string (tr ("Vanishing edges for interaction gate/source diff (corner interaction) - gate shape ignored")));
+            continue;
+          }
         }
 
-        if (! p->is_box ()) {
-          error (tl::to_string (tr ("Gate shape is not a box - width and length may be incorrect")), *p);
+        {
+          db::Edges edges (rgate.edges () & ddiff2gate.edges ());
+          ddwidth = edges.length ();
+          if (ddwidth == 0) {
+            error (tl::to_string (tr ("Vanishing edges for interaction gate/drain diff (corner interaction) - gate shape ignored")));
+            continue;
+          }
         }
 
+        //  Computation of the gate length and width - this scheme is compatible with
+        //  non-rectangular gates and circular gates. The computation is based on the
+        //  relationship: A(gate) = L(gate) * W(gate). W(gate) is determined from the
+        //  accumulated edge lengths (average of left and right length).
+        double param_w = sdbu () * (sdwidth + ddwidth) * 0.5;
+        double param_l = sdbu () * sdbu () * double (rgate.area ()) / param_w;
+
         db::Device *device = create_device ();
 
         device->set_trans (db::DCplxTrans ((p->box ().center () - db::Point ()) * dbu ()));
 
-        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_W, sdbu () * edges.length () * 0.5);
-        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_L, sdbu () * (p->perimeter () - edges.length ()) * 0.5);
+        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_W, param_w);
+        device->set_parameter_value (db::DeviceClassMOS3Transistor::param_id_L, param_l);
 
         for (int diff_index = 0; diff_index < 2; ++diff_index) {
 
@@ -272,6 +304,7 @@ void NetlistDeviceExtractorMOS3Transistor::extract_devices (const std::vector<db
         modify_device (*p, layer_geometry, device);
 
         //  output the device for debugging
+        db::Region diff2gate = sdiff2gate + ddiff2gate;
         device_out (device, diff2gate, rgate);
 
       }
diff --git a/src/db/unit_tests/dbNetlistDeviceExtractorTests.cc b/src/db/unit_tests/dbNetlistDeviceExtractorTests.cc
index 3cba2aaf5..1deab52eb 100644
--- a/src/db/unit_tests/dbNetlistDeviceExtractorTests.cc
+++ b/src/db/unit_tests/dbNetlistDeviceExtractorTests.cc
@@ -21,8 +21,14 @@
 */
 
 #include "dbNetlistDeviceExtractor.h"
+#include "dbLoadLayoutOptions.h"
+#include "dbReader.h"
+#include "dbRecursiveShapeIterator.h"
+#include "dbNetlistDeviceExtractorClasses.h"
 
 #include "tlUnitTest.h"
+#include "tlFileUtils.h"
+#include "tlStream.h"
 
 TEST(1_NetlistDeviceExtractorErrorBasic)
 {
@@ -83,3 +89,717 @@ TEST(2_NetlistDeviceExtractorErrors)
   EXPECT_EQ (error2string (errors [2]), ":cat1:desc1:():msg1");
   EXPECT_EQ (error2string (errors [3]), ":cat1:desc1:(10,11;10,13;12,13;12,11):msg3");
 }
+
+TEST(10_MOS3DeviceExtractorTest)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos3_1.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("MOS3");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=0.8,AS=0.4,AD=0.16,PS=2.6,PD=2);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-100,600;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+}
+
+TEST(11_MOS3DeviceExtractorTestNotRectangularGate)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos3_2.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("MOS3");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=1,AS=0.32,AD=0.18,PS=2.6,PD=2.4);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-300,600;-300,200;-100,200;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,500;0,500;0,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+}
+
+TEST(12_MOS3DeviceExtractorTestCircular)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos3_3.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("MOS3");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=3.8,AS=0.4,AD=4.18,PS=2.6,PD=14.6);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(200,-200;200,600;700,600;700,-200)");
+  EXPECT_EQ (o2.to_string (), "(-600,-1200;-600,1400;1600,1400;1600,-1200/-100,-500;1000,-500;1000,900;-100,900)");
+  EXPECT_EQ (o3.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+}
+
+TEST(20_MOS4DeviceExtractorTest)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos4_1.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("MOS4");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=0.8,AS=0.4,AD=0.16,PS=2.6,PD=2);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-100,600;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+  EXPECT_EQ (o4.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+}
+
+TEST(21_MOS4DeviceExtractorTestNotRectangularGate)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos4_2.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("MOS4");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=1,AS=0.32,AD=0.18,PS=2.6,PD=2.4);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-300,600;-300,200;-100,200;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,500;0,500;0,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+  EXPECT_EQ (o4.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+}
+
+TEST(22_MOS4DeviceExtractorTestCircular)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "mos4_3.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("MOS4");
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["SD"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device MOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=3.8,AS=0.4,AD=4.18,PS=2.6,PD=14.6);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(200,-200;200,600;700,600;700,-200)");
+  EXPECT_EQ (o2.to_string (), "(-600,-1200;-600,1400;1600,1400;1600,-1200/-100,-500;1000,-500;1000,900;-100,900)");
+  EXPECT_EQ (o3.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+  EXPECT_EQ (o4.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+}
+
+TEST(30_DMOS3DeviceExtractorTest)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos3_1.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("DMOS3", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=0.8,AS=0.4,AD=0.16,PS=2.6,PD=2);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-100,600;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+}
+
+TEST(31_DMOS3DeviceExtractorTestNotRectangularGate)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos3_2.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("DMOS3", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=1,AS=0.32,AD=0.18,PS=2.6,PD=2.4);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-300,600;-300,200;-100,200;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,500;0,500;0,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+}
+
+TEST(32_DMOS3DeviceExtractorTestCircular)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos3_3.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS3Transistor ex ("DMOS3", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS3 $1 (S=(null),G=(null),D=(null)) (L=0.3,W=3.8,AS=0.4,AD=4.18,PS=2.6,PD=14.6);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(200,-200;200,600;700,600;700,-200)");
+  EXPECT_EQ (o2.to_string (), "(-600,-1200;-600,1400;1600,1400;1600,-1200/-100,-500;1000,-500;1000,900;-100,900)");
+  EXPECT_EQ (o3.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+}
+
+TEST(40_DMOS4DeviceExtractorTest)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos4_1.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("DMOS4", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=0.8,AS=0.4,AD=0.16,PS=2.6,PD=2);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-100,600;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+  EXPECT_EQ (o4.to_string (), "(-100,-200;-100,600;200,600;200,-200)");
+}
+
+TEST(41_DMOS4DeviceExtractorTestNotRectangularGate)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos4_2.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("DMOS4", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=1,AS=0.32,AD=0.18,PS=2.6,PD=2.4);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(-600,-200;-600,600;-300,600;-300,200;-100,200;-100,-200)");
+  EXPECT_EQ (o2.to_string (), "(200,-200;200,500;0,500;0,600;400,600;400,-200)");
+  EXPECT_EQ (o3.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+  EXPECT_EQ (o4.to_string (), "(-100,-200;-100,200;-300,200;-300,600;0,600;0,500;200,500;200,-200)");
+}
+
+TEST(42_DMOS4DeviceExtractorTestCircular)
+{
+  db::Layout ly;
+
+  {
+    db::LoadLayoutOptions options;
+
+    std::string fn (tl::testsrc ());
+    fn = tl::combine_path (fn, "testdata");
+    fn = tl::combine_path (fn, "algo");
+    fn = tl::combine_path (fn, "dmos4_3.gds");
+
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly, options);
+  }
+
+  db::Cell &tc = ly.cell (*ly.begin_top_down ());
+
+  db::DeepShapeStore dss;
+  dss.set_text_enlargement (1);
+  dss.set_text_property_name (tl::Variant ("LABEL"));
+
+  //  original layers
+  db::Region l0 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(0, 0))), dss);
+  db::Region l1 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(1, 0))), dss);
+  db::Region l2 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(2, 0))), dss);
+  db::Region l3 (db::RecursiveShapeIterator (ly, tc, ly.get_layer (db::LayerProperties(3, 0))), dss);
+  db::Region o1 (dss);
+  db::Region o2 (dss);
+  db::Region o3 (dss);
+  db::Region o4 (dss);
+
+  //  perform the extraction
+
+  db::Netlist nl;
+  db::hier_clusters<db::PolygonRef> cl;
+
+  db::NetlistDeviceExtractorMOS4Transistor ex ("DMOS4", true);
+
+  db::NetlistDeviceExtractor::input_layers dl;
+
+  dl["S"] = &l0;
+  dl["D"] = &l1;
+  dl["G"] = &l2;
+  dl["W"] = &l3;
+  dl["tS"] = &o1;
+  dl["tD"] = &o2;
+  dl["tG"] = &o3;
+  dl["tB"] = &o4;
+  ex.extract (dss, 0, dl, nl, cl);
+
+  EXPECT_EQ (nl.to_string (),
+    "circuit TOP ();\n"
+    "  device DMOS4 $1 (S=(null),G=(null),D=(null),B=(null)) (L=0.3,W=3.8,AS=0.4,AD=4.18,PS=2.6,PD=14.6);\n"
+    "end;\n"
+  );
+  EXPECT_EQ (o1.to_string (), "(200,-200;200,600;700,600;700,-200)");
+  EXPECT_EQ (o2.to_string (), "(-600,-1200;-600,1400;1600,1400;1600,-1200/-100,-500;1000,-500;1000,900;-100,900)");
+  EXPECT_EQ (o3.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+  EXPECT_EQ (o4.to_string (), "(-100,-500;-100,900;1000,900;1000,-500/200,-200;700,-200;700,600;200,600)");
+}
diff --git a/testdata/algo/dmos3_1.gds b/testdata/algo/dmos3_1.gds
new file mode 100644
index 000000000..8147394b5
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diff --git a/testdata/algo/dmos3_2.gds b/testdata/algo/dmos3_2.gds
new file mode 100644
index 000000000..f1a06d8eb
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diff --git a/testdata/algo/dmos3_3.gds b/testdata/algo/dmos3_3.gds
new file mode 100644
index 000000000..06339dfd6
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diff --git a/testdata/algo/dmos4_1.gds b/testdata/algo/dmos4_1.gds
new file mode 100644
index 000000000..90c142e0b
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diff --git a/testdata/algo/dmos4_2.gds b/testdata/algo/dmos4_2.gds
new file mode 100644
index 000000000..7980087b6
Binary files /dev/null and b/testdata/algo/dmos4_2.gds differ
diff --git a/testdata/algo/dmos4_3.gds b/testdata/algo/dmos4_3.gds
new file mode 100644
index 000000000..19d0be61a
Binary files /dev/null and b/testdata/algo/dmos4_3.gds differ
diff --git a/testdata/algo/mos3_1.gds b/testdata/algo/mos3_1.gds
new file mode 100644
index 000000000..fec1a662a
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diff --git a/testdata/algo/mos3_2.gds b/testdata/algo/mos3_2.gds
new file mode 100644
index 000000000..6750aa5f8
Binary files /dev/null and b/testdata/algo/mos3_2.gds differ
diff --git a/testdata/algo/mos3_3.gds b/testdata/algo/mos3_3.gds
new file mode 100644
index 000000000..380bb8857
Binary files /dev/null and b/testdata/algo/mos3_3.gds differ
diff --git a/testdata/algo/mos4_1.gds b/testdata/algo/mos4_1.gds
new file mode 100644
index 000000000..537a540ef
Binary files /dev/null and b/testdata/algo/mos4_1.gds differ
diff --git a/testdata/algo/mos4_2.gds b/testdata/algo/mos4_2.gds
new file mode 100644
index 000000000..98b1f4adb
Binary files /dev/null and b/testdata/algo/mos4_2.gds differ
diff --git a/testdata/algo/mos4_3.gds b/testdata/algo/mos4_3.gds
new file mode 100644
index 000000000..bfcb04fc2
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