a connection testing apparatus , a connection testing method , and a chip using the same are provided . the method can be used for testing connections between chips , so as to solve the problems that a conventional multi - chip connection test needs a plenty of test patterns , resulting in a long test time and a high test cost , and the condition of a connection failure is hard to be analyzed after a test failure . in the present invention , a voltage variation caused when an esd element in a chip is conducted and a comparison circuits are used to determine whether a connection is correct . furthermore , the test apparatus is built in the chip , so that the connection test may be accomplished quickly and efficiently . once a connection failure occurs , the failed connection pin can also be found , so as to be favorable for engineering analysis and thereby effectively saving the test cost .