Delta-IDDQ Testing of a CMOS 12-Bit Charge Scaling DigitaltoAnalog Converter

We present design, implementation and test of a built-in current sensor for Delta-IDDQ testing of a CMOS 12-bit charge scaling digital-to-analog converter (DAC). The sensor uses power discharge method for the fault detection. The integrated sensor and the DAC on a chip have been designed and implemented in a 0.5 mum n-well CMOS technology. The DAC uses charge scaling method for the design and a low voltage (0 to 2.5 V) folded cascode op-amp. The built-in current sensor (BICS) has a resolution of 0.5 muA. Faults have been introduced into the DAC using fault injection transistors (FITs). Fault detection by the BICS has been verified both from simulation and experimental measurements.