I Introduction
The electronics circuitry of general biomedical implantable devices like pacemakers, cochlear implants, neural prostheses. ..etc, consists of battery for energy delivery, signal acquisition and signal processing blocks, analog-to-digital conversion block, and also communication subsystems block (figure 1). Each of these blocks must be designed to meet strict constraints that make them more and more sophisticated and efficient. These constraints generally concern reliability, robustness, precision and low power consumption [1].