Verilog (-ams) 1364-2005 Simulator for analog designs (freeware)

I was doing digital design with Verilog using Xilinx ISE. Now I want to start analog design using Verilog-ams. But I don't know which simulator (freeware) I should use, because Xilinx ISE is not supporting analog designs with Verilog ams. Please suggest me some simulators supported to verilog 1364-2005.