Dynamic Monitoring of Circuit Performance to Make On-Demand Adjustments to Account for End-of-Life Effects
Publication Date: 2014-Jul-31
The IP.com Prior Art Database
Described is a method of monitoring critical circuit parameters for "end-of-life" performance impacts and providing feedback control to compensate for the resulting performance degradations as the device ages. Monitored critical circuit parameters such as current, delay, device voltage, or threshold are compared against a reference circuit to dynamically determine "end-of-life" type performance impacts.
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Dynamic Monitoring of Circuit Performance to Make On - Account for End -
This article describes a method of monitoring critical circuit parameters for "end-of-life" performance impacts and providing feedback control to compensate for the resulting performance degradations as the device ages. Monitored critical circuit parameters such as current, delay, device voltage, or threshold are compared against a reference circuit to dynamically determine "end-of-life" type performance impacts. This information is used to generate feedback control that is used to adjust local circuit controls (such as local regulated power supply levels, reference currents, digital to analog converter (DAC) settings, etc.) to compensate and minimize performance loss as the parts age. The method can be used to independently maintain the performance of critical path circuits, SRAM, analog circuits, or applied to an entire chip as required.
As silicon technology advances, larger requirements are placed on circuit designers to account for expected end-of-life (EOL) impacts during design. This is typically done by building in performance margin to assure full functionality as a circuit ages. This can lead to "over-designed" circuits with extra complexity, larger size, and which burn excess power. Having the ability to compensate for EOL performance degradations can simplify requirements for designing robust product.
The idea presented here is to monitor local circuit performance (by one or more performance monitor means, such as already existing monitors for current draw, critical path delay, ring oscillator frequency, device Vt, etc.) and make decisions based on the results to dynamically adjust some means of compensation to correct for any losses that occur as the part ages (such as a local circuit power supply through a regulator, current or voltage DAC adjustments for analog current or voltage bias control, or other means specific to the circuit of interest.). One unique method to do this is to have a replica reference circuit (or part) that operates in the same mode as the target circuit, but is normally off, and only is enabled when it is desired to observe a delta as shown in Figure 1 below. At the designated time to monitor, both the functional circuit and the replica are enabled in the same fashion and any changes in performance are noted. A decision is made based on these changes whether to adjust the local power supply to compensate, or not. The reference circuit should normally be placed in a state where the expected end-of-life shifts (aging effects) would be minimized, such that changes to the functional circuit performance would be observable as deltas to the reference circuit. This could mean being disabled, or having power removed completely, or any other means to prevent or minimize degradation. The idea could further be extended as shown in Figure 2 below to monitor various parameters of interest and dynamically compensate for EOL degradation...