Patent ID: 7274250
Filing Date: 2007-09-25
Classification: G05F

Abstract:
1. An apparatus comprising: a first bias circuit to bias a first component with an exponential dependency of current on voltage (“exponential I(V) characteristic”) at a first point of its range; a second, independent bias circuit to bias a second component with an exponential I(V) characteristic at a second point of its range, the first point being different than the second point; a resistive impedance in series with the second component; a first voltage divider to produce a first voltage proportional to a voltage across the first component; a second voltage divider to produce a second voltage proportional to a sum of a voltage across the second component and a voltage across the resistive impedance; and an active component to compare the first voltage and the second voltage and to produce a reference voltage; wherein in operation a current through each voltage divider is greater than zero, and the bias circuits are powered by the reference voltage.