Patent ID: 8378868

Claim:
A system comprising: a sigma-delta (ΣΔ) modulator with a first positive reference and a first negative reference, the ΣΔ modulator configured to interface with a charge storage device, the ΣΔ modulator further configured to output a digital representation of a voltage potential of the charge storage device, the first positive reference electrically connected to a first terminal of the charge storage device and the first negative reference electrically connected to a second terminal of the charge storage device; and a second ΣΔ modulator, the second ΣΔ modulator with a second positive reference and a second negative reference, the second ΣΔ modulator configured to interface with a second charge storage device, the second negative reference electrically connected to the first positive reference, the second ΣΔ modulator further configured to output a digital representation of a voltage potential of the second charge storage device, the second positive reference electrically connected to a first terminal of the second charge storage device and the negative reference electrically connected to a second terminal of the second charge storage device.