Semi-digital off-chip I_DDQ monitor developments: towardsa general-purpose digital current monitor

摘要

This paper presents some of the steps taken towards the design andrealisation of a general-purpose fully digital I_DDQ monitorbased upon the OCIMU circuit. It focuses in more detail on two of thepossible implementation routes, the design and realisation of aprogrammable monitor, based on discrete components, and the design of afully integrated monolithic version. Both circuits operate as asemi-digital monitor, are capable to drive a high capacitive load, canbe used in combination with standard ATE, and are invisible to the DUT,so that its operation is not affected by the monitor. Both monitors aredesigned to measure currents up to 1 mA within a 10 kHz test cycle. Theresolution of the discrete programmable current monitor is function ofthe configuration selected and its best value is 80 nA. Simulations ofthe monolithic version, implemented in 2 μm BiCMOS technology show anaccuracy better than 1 μA, similar to the OCIMU circuit