The paper deals with a new approach to the design of adaptive hardware using common Field Programmable Gate Arrays (FPGA). The ultimate aim is to develop evolvable IP (Intellectual Property) cores. The cores should be reused in the same way as ordinary IP cores are reused. In contrast to the conventional cores, the evolvable cores are able to perform autonomous evolution of their internal circuits. The cores should be available in the form of HDL source code, i.e. they should be synthesizable into any reconfigurable device of a sufficient capacity. The approach is based on implementation of a virtual reconfigurable circuit and a genetic unit in an ordinary FPGA. In the presented case study an adaptive image filter is designed, implemented and synthesized. The proposed idea of evolvable IP core could open the way towards defining a business model for evolvable hardware.