The paper describes a self-biased CMOS transistor circuit with two outputs
providing the transistor threshold voltages, V-TP and -V-TN. Both outputs a
re referenced to the same V-DD supply line, and hence, the circuit can be u
sed as a convenient test device. The V-TP extractor is based on the "nested
" connection of two transistors; the -V-TN extractor is designed using the
difference of gate-source voltages in two different size transistors carryi
ng equal currents. The circuit was realized in 0.8 mu m technology, and the
results of simulation and experiment are compared. Recommendations to impr
ove the design are given.