diff --git a/include/sta/Liberty.hh b/include/sta/Liberty.hh
index 145bdf74..d57bd911 100644
--- a/include/sta/Liberty.hh
+++ b/include/sta/Liberty.hh
@@ -31,6 +31,7 @@ namespace sta {
 class LibertyCellIterator;
 class LibertyCellPortIterator;
 class LibertyCellPortBitIterator;
+class LibertyCellPgPortIterator;
 class LibertyPortMemberIterator;
 class ModeValueDef;
 class TestCell;
@@ -397,7 +398,8 @@ public:
   void findLibertyPortsMatching(PatternMatch *pattern,
 				LibertyPortSeq *ports) const;
   bool hasInternalPorts() const { return has_internal_ports_; }
-  LibertyPgPort *findPgPort(const char *name);
+  LibertyPgPort *findPgPort(const char *name) const;
+  size_t pgPortCount() const { return pg_port_map_.size(); }
   ScaleFactors *scaleFactors() const { return scale_factors_; }
   void setScaleFactors(ScaleFactors *scale_factors);
   ModeDef *makeModeDef(const char *name);
@@ -580,6 +582,7 @@ private:
 
   friend class LibertyLibrary;
   friend class LibertyCellPortIterator;
+  friend class LibertyCellPgPortIterator;
   friend class LibertyPort;
   friend class LibertyBuilder;
   friend class LibertyCellTimingArcSetIterator;
@@ -613,6 +616,19 @@ private:
   ConcreteCellPortBitIterator *iter_;
 };
 
+class LibertyCellPgPortIterator : public Iterator<LibertyPgPort*>
+{
+public:
+  LibertyCellPgPortIterator(const LibertyCell *cell);
+  bool hasNext();
+  LibertyPgPort *next();
+
+private:
+  DISALLOW_COPY_AND_ASSIGN(LibertyCellPgPortIterator);
+
+  LibertyPgPortMap::Iterator iter_;
+};
+
 class LibertyCellTimingArcSetIterator : public TimingArcSetSeq::ConstIterator
 {
 public:
@@ -1065,12 +1081,14 @@ public:
   LibertyPgPort(const char *name,
 		LibertyCell *cell);
   ~LibertyPgPort();
-  const char *name() { return name_; }
+  const char *name() const { return name_; }
   LibertyCell *cell() const { return cell_; }
   PgType pgType() const { return pg_type_; }
   void setPgType(PgType type);
   const char *voltageName() const { return voltage_name_; }
   void setVoltageName(const char *voltage_name);
+  static bool equiv(const LibertyPgPort *port1,
+		    const LibertyPgPort *port2);
 
 private:
   const char *name_;
diff --git a/liberty/EquivCells.cc b/liberty/EquivCells.cc
index 17c9f176..5390fdda 100644
--- a/liberty/EquivCells.cc
+++ b/liberty/EquivCells.cc
@@ -41,6 +41,14 @@ static unsigned
 hashFuncExpr(const FuncExpr *expr);
 static unsigned
 hashPort(const LibertyPort *port);
+static unsigned
+hashCellPgPorts(const LibertyCell *cell);
+static unsigned
+hashPgPort(const LibertyPgPort *port);
+
+static bool
+equivCellPgPorts(const LibertyCell *cell1,
+                 const LibertyCell *cell2);
 
 static float
 cellDriveResistance(const LibertyCell *cell)
@@ -164,7 +172,9 @@ EquivCells::mapEquivCells(const LibertyLibrary *library,
 static unsigned
 hashCell(const LibertyCell *cell)
 {
-  return hashCellPorts(cell) + hashCellSequentials(cell);
+  return hashCellPorts(cell)
+    + hashCellPgPorts(cell)
+    + hashCellSequentials(cell);
 }
 
 static unsigned
@@ -188,6 +198,25 @@ hashPort(const LibertyPort *port)
     + port->direction()->index() * 5;
 }
 
+static unsigned
+hashCellPgPorts(const LibertyCell *cell)
+{
+  unsigned hash = 0;
+  LibertyCellPgPortIterator port_iter(cell);
+  while (port_iter.hasNext()) {
+    LibertyPgPort *port = port_iter.next();
+    hash += hashPgPort(port);
+  }
+  return hash;
+}
+
+static unsigned
+hashPgPort(const LibertyPgPort *port)
+{
+  return hashString(port->name()) * 3
+    + static_cast<int>(port->pgType()) * 5;
+}
+
 static unsigned
 hashCellSequentials(const LibertyCell *cell)
 {
@@ -232,6 +261,7 @@ equivCells(const LibertyCell *cell1,
 	   const LibertyCell *cell2)
 {
   return equivCellPortsAndFuncs(cell1, cell2)
+    && equivCellPgPorts(cell1, cell2)
     && equivCellSequentials(cell1, cell2)
     && equivCellTimingArcSets(cell1, cell2);
 }
@@ -279,6 +309,25 @@ equivCellPorts(const LibertyCell *cell1,
   }
 }
 
+static bool
+equivCellPgPorts(const LibertyCell *cell1,
+                 const LibertyCell *cell2)
+{
+  if (cell1->pgPortCount() != cell2->pgPortCount())
+    return false;
+  else {
+    LibertyCellPgPortIterator port_iter1(cell1);
+    while (port_iter1.hasNext()) {
+      LibertyPgPort *port1 = port_iter1.next();
+      const char* name = port1->name();
+      LibertyPgPort *port2 = cell2->findPgPort(name);
+      if (!(port2 && LibertyPgPort::equiv(port1, port2)))
+        return false;
+    }
+    return true;
+  }
+}
+
 bool
 equivCellSequentials(const LibertyCell *cell1,
 		     const LibertyCell *cell2)
diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 280863f7..bdb8719c 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -942,7 +942,7 @@ LibertyCell::addPgPort(LibertyPgPort *pg_port)
 }
 
 LibertyPgPort *
-LibertyCell::findPgPort(const char *name)
+LibertyCell::findPgPort(const char *name) const
 {
   return pg_port_map_.findKey(name);
 }
@@ -2930,4 +2930,34 @@ LibertyPgPort::setVoltageName(const char *voltage_name)
   voltage_name_ = stringCopy(voltage_name);
 }
 
+bool
+LibertyPgPort::equiv(const LibertyPgPort *port1,
+                     const LibertyPgPort *port2)
+{
+  return stringEq(port1->name_, port2->name_)
+    && port1->pg_type_ == port2->pg_type_;
+}
+
+////////////////////////////////////////////////////////////////
+
+LibertyCellPgPortIterator::LibertyCellPgPortIterator(const LibertyCell *cell) :
+  iter_(const_cast<LibertyCell*>(cell)->pg_port_map_)
+{
+}
+
+bool
+LibertyCellPgPortIterator::hasNext()
+{
+  return iter_.hasNext();
+}
+
+LibertyPgPort *
+LibertyCellPgPortIterator::next()
+{
+  const char *name;
+  LibertyPgPort *port;
+  iter_.next(name, port);
+  return port;
+}
+
 } // namespace