A sub-µ W conductance converter for bioimplantable devices

This article describes a new electrical conductance converter method suitable for very low power applications, where energy constraints prevail over speed and measurement accuracy. This method gathers voltage integration and shopper stabilization techniques to process noisy Ion level signals and overcome severe limitations of weak inversion channel CMOS circuitry. Main features, tradeoffs and upgrades are exploited. Besides that, the paper presents the circuit schematics for a standard 0.35 µm CMOS implementation. Post-layout simulations show a total current consumption lower than 750nA, including current source excitation inherent to the conductance measurement. Such low power consumption allows measuring several physical parameters using self-powered wireless sensors networks