The hunt for electrical bugs begins with the Shmoo plot. The Shmoo plot shows whether the device under test (DUT) passed or failed when various combinations of parameters are applied to the DUT. A Shmoo plot is a graphical representation of a series of measurements in which you measure e.g pass/fail characteristics while sweeping a number of variables.
In the example, we will illustrate the Shmoo plot by measuring the effect of power starvation on performance. Each measurement represents a set of test patterns applied to the DUT, and the test is repeated for a number of operating conditions by sweeping:
The entire test pattern set will be applied to the DUT for a given set of operating conditions. If the DUT passes the test for the given set, this will be represented by a green dot, otherwise the test will be marked by a red dot.