On-chip current sensing circuit for CMOS VLSI

CMOS is a popular technology today for very large scale integrated (VLSI) circuits. But, conventional functional testing cannot guarantee the detection of some defects. Built-in current testing has been suggested to enhance the defect coverage. In this paper, the authors present a high-speed built-in current sensing (BICS) circuit design. An experimental CMOS VLSI chip containing BICS is described. The power bus current of an 8×8 parallel multiplier is monitored. This BICS detects all implanted short circuit defects and some open circuit defects at a clock speed of 30 MHz (limited by the test set up). SPICE3 simulations indicate a defect detection time of 2 ns