On-chip current measurement for multi-site electromigration monitoring

Power consumption and die heating are of major concern in high-density high-speed integrated circuits. The performance of modern IC designs is limited by power consumption and thermal issues. Direct and continuous measurement of on-chip currents is becoming increasingly common in interconnects at multiple locations on a die with real time feedback to the controller for efficient load management and/or load balancing and system performance optimization. The demand for good on-chip current sensors to support such applications is growing. These on-chip current sensors should have sufficient accuracy as well as compact area and low power consumption.;This thesis introduces on-chip current measurement method providing performance improvement as well as lifetime electromigration management. The inherent voltage drop across existing interconnects is used to determine the current flow rather than inserting shunts in the current-flow paths for creating voltage drops. Current is measured with a MOSFET-only sensing circuit providing 9 bits of resolution with midrange current levels at the threshold where electromigration concerns become relevant. This current sensor can be used for sensing currents in either VDD or VSS busses and is targeted for use in power/thermal management units of integrated circuits. Simulation results show the DNL/INL of this sensor is within +0.15/-0.3 LSB. The current sensor is proved still useful with respect to local mismatches. The small area and low power dissipation make the structure suitable for multiple-site on-chip current measurements.