Testing Embedded Toggle Pattern Generation Through On-Chip IR Drop Monitoring

On-chip monitor (OCM) circuits capture dynamic power-supply (PS) waveforms within power domains individually bounded by dedicated micro voltage regulator modules (μVRMs). This paper uses OCM to diagnose VLSI circuits with a modular power management, where the evolution over time of the gate switching count, in the clock tree, the flip-flops, and the combinational logics are precisely captured in the OCM voltage waveforms. A mismatch between simulation and measurement gives us a warning for either (1) faulty behavior in the IC hardware, or (2) bugs in the test program. In this paper, we demonstrate an IR-drop-based toggle diagnosis technique using OCM for a prototype chip in 180 nm technology. The OCM measurements at 100 ps and 100 μV are capable of reaching a resolution of 18.7 fC/gate. This is approximately equivalent to the amount of charge consumed by a single two-input NAND gate.