Patent ID: 8575971

Claim:
A circuit comprising: a first node and a second node; a first switch and a second switch, the first switch coupled to the first node and having an open configuration and a closed configuration, the second switch coupled to the second node and having an open configuration and a closed configuration; a first current mirror and a second current mirror, the first current mirror coupled to the first switch and configured to provide a first current mirror current, the second current mirror coupled to the second switch and configured to provide a second current mirror current; a sigma delta modulator having an input and an output, the input coupled to the first node and the output coupled to the first switch and the second switch, the output configured to provide a discrete pulse density modulated output to control the open configuration and the closed configuration of the first switch and the second switch, the discrete pulse density modulated output represents a first current source current as a function of the first current mirror current, wherein the second current mirror current subtracts at least a portion of a second current source current at the second node when the second switch is in the closed configuration.