Validation signature testing: A methodology for post-silicon validation of analog/mixed-signal circuits

Due to the use of scaled technologies, high levels of integration and high speeds of today's mixed-signal SoCs, the problem of validating correct operation of the SoC under electrical bugs and that of debugging yield loss due to unmodeled multi-dimensional variability effects is extremely challenging. Precise simulation of all electrical aspects of the design including the interfaces between digital and analog circuitry, coupling across power and ground planes, crosstalk, etc., across all process corners is very hard to achieve in a practical sense. The problem is expected to get worse as analog/mixed-signal/RF devices scale beyond the 45nm node and are more tightly integrated with digital systems than at present. In this context, a post-silicon validation methodology for analog/mixed-signal/RF SoCs is proposed that relies on the use of special stimulus designed to expose differences between observed DUT behavior and its predictive model. The corresponding error signature is then used to identify the likely “type” of electrical bug and its location in the design using nonlinear optimization algorithms. Results of trial experiments on RF devices are presented.