Fully Digital Process Variation Sensor for High Performance System-on-a-Chip

Sammanfattning

Integrated Circuit (IC) designers have always faced the problem of small deviations in parameters of their designs in manufactured ICs. This variation due to the manufacturing process (Process Variation) in device parameters from their nominal values result in altered performance and can cause integrated circuits to be malfunctioning. With Moore’s Law going strong, the device dimensions of integrated circuits continue to shrink. This is exacerbating the issue with deviations from nominal design values. Several methods and techniques are employed to reduce the impact of this type of undesirable variation. This thesis explores a method of measuring the variation inside an IC. An accurate measurement of the variation has the potential to enable compensation techniques, tuning performance to desirable levels or even turning a malfunctioning ICs into functional ones. This thesis proposes a method to obtain an accurate digital representation of the variation, a Process Sensor. The proposed sensor is capable of detecting the variation in P-type Metal Oxide Semiconductor (PMOS) and N-type Metal Oxide Semiconductor (NMOS) devices independently. In addition, a theoretical method to disentangle the temperature dependence from the variation measurement is explored. And conversely via the same method, temperature dependence can be increased, effectively turning the process sensing circuitry into a temperature sensing circuitry.