Semi-digital off-chip I/sub DDQ/ monitor developments: towards a general-purpose digital current monitor

Abstract

This paper presents some of the steps taken towards the design and realisation of a general-purpose fully digital I/sub DDQ/ monitor based upon the OCIMU circuit. It focuses in more detail on two of the possible implementation routes, the design and realisation of a programmable monitor, based on discrete components, and the design of a fully integrated monolithic version. Both circuits operate as a semi-digital monitor, are capable to drive a high capacitive load, can be used in combination with standard ATE, and are invisible to the DUT, so that its operation is not affected by the monitor. Both monitors are designed to measure currents up to 1 mA within a 10 kHz test cycle. The resolution of the discrete programmable current monitor is function of the configuration selected and its best value is 80 nA. Simulations of the monolithic version, implemented in 2 /spl mu/m BiCMOS technology show an accuracy better than 1 /spl mu/A, similar to the OCIMU circuit.