Current-testable high-frequency CMOS operational amplifiers

A new test approach for high-frequency operational amplifiers based on current injection is presented in this paper. Current-based test stimuli allow detection of some faults which are difficult to detect or are untestable when conventional voltage-based test stimuli are used. In addition, the selection of test stimuli is simpler since faulty behaviours are observable in the whole frequency band with current injection. An example of a current-testable operational amplifier has been designed, and the small test circuitry required for current injection has a negligible impact on circuit performance.