| To realize the full performance potential of CMOS integrated circuits, the power networks supplying them must supply sufficient current, both transient and steady state, so that on-chip supply voltages remain within specified bounds. MOS transistor scaling has resulted in decreased supply voltages and increased circuit density. Since total power dissipation has remained unchanged or even increased, the combined result is a large increase in supply current and its time rate of change, making the design of power networks increasingly difficult. Measurements of voltages and currents in power networks are required to develop good design and simulation practices and to diagnose problems that arise in real systems.; This thesis presents a method that enables transient supply currents to be measured at the package to printed circuit board interface. The approach measures the magnetic fields generated by current carrying conductors. A simple induction loop is used as the magneto-metric device. We demonstrate that such a device can be made small enough to measure PCB vias on 1 mm spacing, have a measurement bandwidth of 2 GHz, and can detect repetitive current changes as small as 6 muA/ns. This sensitivity is sufficient to detect supply current fluctuations in real printed circuit boards. Finally the method is applied to investigate the power network behavior of a large integrated circuit. |
