Accurate MOS threshold voltage detector for bias circuitry

A circuit for the detection of the threshold voltage V/sub TH/ of MOS devices is presented. The basic scheme proposed here is implemented in BiCMOS technology but can also be applied in any standard CMOS process. The deviation of the detected V/sub TH/ from the actual (or extrapolated) one is analytically estimated, taking into account the effects due to channel length modulation and mobility modulation. The results obtained show that the error at ambient temperature is lower than 0.6% for all values of V/sub DD/ larger than 3.25 V, and for temperatures in the range -25 degrees C to 125 degrees C the error is never higher than 4%.<
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