TEST PROCEDURES FOR ACTIVE FOLLOW-UP AND HALF-READ REPRESENTATIVES (COMPARATOR) IN A SINGLE PROGRAMME SALIDATED POLY SHELL SECURITY

摘要

A non intrusive isolation testing method for each of the positive and negative input (in+ & in-) to each comparator in the array is provided. Isolation does not affect the read capability of the comparator and therefore characterization of the comparator is accomplished by using the normal read circuits of the one time programmable (OTP) array. The isolation method relies on gating the control signals by using test signals; as a result inputs to a comparator are not affected electrically. Each input has four possible control signals and therefore needs four gating test signal drivers and so a total of 16 input combinations are available to each comparator.