DEVELOPMENT OF BIO-IMPLANTED MICRO-SYSTEM WITH SELF-RECOVERY ASK DEMODULATOR FOR TRANSCUTANEOUS APPLICATIONS

Abstract

This paper deals with the development of bio-implanted micro-system with low-power and high data rate based on amplitude shift keying (ASK) modulation technique to stimulate nerves and muscles. The modified system is operated by a low-frequency band 13.56 MHz according to the industrial-scientific-medical (ISM) bands to avoid the biological tissue damage. The data rate on the demodulator side is from 1 Mb/s and up to 1.5 Mb/s depending of generating binary signal (T BIT = 1 μs or 0.5 μs) with modulation index of 13% and modulation rate 7.3%, 9% and 11%, respectively. The proposed inductive coupling link achieves 73% of link efficiency. The modified rectifier with self-threshold voltage cancellation techniques and voltage regulator without thermal protection circuit and without passive elements occupies small area that is modified to generate adequate and stable DC voltages of 1.8 V. A new ASK demodulator structure based on two comparators is developed to extract a synchronized demodulated signal with minimum error. Thereby no need for clock recovery circuit and delay-locked loops (DLL) circuits for data synchronization at 1 Mb/s and 1.250 Mb/s of speed. The system designed using OrCAD Pspice 16.2 is based on 0.35 μm technologies.