diff -Naur mig_36_1.org/user_design/rtl/mig_36_1_infrastructure.vhd mig_36_1/user_design/rtl/mig_36_1_infrastructure.vhd
--- mig_36_1.org/user_design/rtl/mig_36_1_infrastructure.vhd	2011-11-19 22:36:33.000000000 +0100
+++ mig_36_1/user_design/rtl/mig_36_1_infrastructure.vhd	2011-11-21 22:59:00.843954000 +0100
@@ -127,10 +127,11 @@
   
   DIFF_ENDED_CLKS_INST : if(CLK_TYPE = "DIFFERENTIAL") generate
   begin
-    SYS_CLK_INST : IBUFGDS_LVPECL_25
+--    SYS_CLK_INST : IBUFGDS_LVPECL_25
+    SYS_CLK_INST : IBUFG
       port map (
         I  => sys_clk_p,
-        IB => sys_clk_n,
+--        IB => sys_clk_n,
         O  => sys_clk_in
         );
     
