Nokia Corporation

Patrik Bjorksten

Sami Kallioinen

Tom Mikael Ahola

Jukka Wallinheimo

Method and apparatus for reducing power in a switched capacitor circuit. In one embodiment, the power reduction apparatus includes a detector connected to both inputs of an operational amplifier in a switched capacitor circuit, and a controller. The detector monitors the inputs. A voltage corresponding to full settling (i.e. a zero difference between the inputs) is stored. The voltage corresponding to the difference between the inputs is compared to the previous value to determine whether it is within the desired range. The controller is connected to an output signal of the detector. The controller adjusts a bias current of the operational amplifier based on the output signal to as low as possible but just above a value where the comparison falls outside the desired range. The power consumption of the operational amplifier is minimized while a settling time of the operational amplifier is still adequate for maximum performance.

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Helsingfors, Finland

Patrik Bjorksten