Abstract: Multiple techniques are disclosed for hardening a self-clocking circuit against glitches. Glitch filters are placed in some portions of a digital design. In some embodiments the glitch filter is dynamically tunable. In one embodiment the inputs are locked out by the outputs. Methods for evaluating code symbols are presented, as is a circuit for differential signaling.

Abstract: The present invention enables asynchronous circuits to be tested in the same manner and using the same equipment and test strategies as with synchronous circuits. The feedback path of an asynchronous element, for example a Muller C element, includes a test structure which may be invoked for the purpose of providing the means for synchronous testing. When configured for testing, the test structure provides a clocked latching and selecting function which, by virtue of breaking the feedback path of the self-timing device, prevents the device being tested from switching states until desired. When the element is not in test mode, the test structure is configured to pass through the data that normally flows through the feedback path unchanged. The result is an ability to test an asynchronous device or subsystem of a device in the same manner as and/or intermixed with a synchronous device.