US Patent 7447963 Testing of electronic circuits

A plurality of integrated circuits that are used in an electronic circuit have functional interconnections and dedicated test connections. The integrated circuits receive and transmit synchronization information, such as clock signals from one integrated circuit to another successively through the chain. This permits a high-test speed. Preferably the synchronization information is serialized with test data, test results and/or commands. Preferably, the bit rate between successive integrated circuits in the chain is programmable by means of commands transmitted through the chain. Thus, different bit rates may be at different locations along the chain to reduce the delay occurred by the synchronization signals along the chain.