Current sensing for built-in testing of CMOS circuits

Built-in current (BIC) testing involves the monitoring of power bus currents in a VLSI circuit, as a means of detecting processing defects in the circuit. The design and performance of a prototype BIC sensor for static CMOS are discussed. It has been demonstrated that a fully-operational BIC sensor can be designed using a standard CMOS process. The presented design met all basic requirements: it was small, it caused only a small degradation of the performance of the monitored module, and it provided sufficient current resolution. The main disadvantage of the described design, however, was a substrate current caused by the structure of the bipolar transistor