Tracking switched-capacitor CMOS current reference

An integrated CMOS current reference is presented, based on the switched-capacitor (SC) circuit technique. The output current is obtained by applying a given reference voltage, using a feedback loop, to an SC structure which emulates a resistor. The reduced spread in SC equivalent resistor values, combined with the high accuracy in integrated voltage references, ensures low dispersion in the generated current. The obtained current tracks the capacitance per unit area of the structure used to integrate the capacitors. The circuit is therefore useful for biasing operational amplifiers and other active circuitry in high frequency SC or switched-current analogue processors