Ultra-low-power sensor signal processing unit for implantable biosensor applications

In recent years various types of implantable medical devices have been proposed for monitoring various physiological parameters of human body. Long term maintenance-free operation of these devices requires extreme low-power operation to avoid periodic replacement of batteries. For real-time monitoring of health condition, the implantable medical devices also need to transmit the vital information outside of the human body for further diagnostics and processing. This work shows the design and simulation of an ultra-low-power signal processing unit suitable for implantable biosensor applications. The proposed unit comprises of a Data Generator Block, an Impulse Generator Block and a Buffer Block. The Data Generator Block takes the signal from any generic sensor and transforms the sensor signal into frequency modulated digital pulses by employing a relaxation oscillator. The Impulse Generator Block converts the digital pulses into impulse signals for impulse-radio based wireless telemetry. Finally the Buffer Block drives a standard 200Ω antenna load. Use of weak inversion MOSFET and relaxation oscillator structure inside the Data Generator Block facilitate to achieve extreme low-power operation. Simulation results show the effectiveness of the proposed system.