Current Mode Sigma-Delta Modulators Designed for Amperometry Based Medical Sensors

Bio-sensors are important parts of systems monitoring biological processes. Some of the techniques, applied in this type of sensors convert a physical/chemical phenomenon into an electrical current. Important part of such measurement devices is a ADC. The paper reported several structures of current mode Sigma-Delta modulators with ultra-low power consumption and other parameters suitable for this class of systems. An integrator based on a current mirror structure is used as a noise shaping filter. The presented design approach uses the VHDL-AMS models. A final, transistor level structure is also reported.