The use of closed-loop implantable telemetry devices [1,2] is increasing as recent clinical studies have shown their efficiency and usefulness in detecting and treating various cardiac arrhythmias. In this paper, we present a single-chip closed-loop system providing closed-loop feedback of sensed cardiac patterns. This device promises more optimized stimulation parameters to cure rapid arrhythmias compared with open-loop devices. Our system incorporates more functionality comparing with the conventional micro-stimulators, yet consumes less power. It is powered by implanted rechargeable batteries periodically charged by radio-frequency (RF) coupling. This improvement of the powering system can prevent improper device operation or shutdown due to RF coupling and loading variations. Furthermore, this system eliminates the need for periodic surgery for battery replacement and improves quality of life of the patient.