An inductive wireless telemetry circuit with OOK modulation for implantable cardiac pacemakers

An inductive wireless telemetry circuit for implantable cardiac pacemakers is presented in this paper. An internal coil in the titanium case transmits the detected cardiac data into the coil of the outside programmer. The configuration data and the commands from the programmer are sent to the pacemaker through the same pair of coils to save volume of the system. In order to realize reliable and low-power communication through the titanium housing, OOK modulation with a carrier frequency of 128 KHz is adopted for the system. The internal demodulator is realized simply with a diode-based rectifier, while the external demodulation circuit is realized with a front-end active band-pass filter and a DFF-based low-pass filter. Measurement from a prototype system with discrete components shows that a raw data-rate of 8 Kb/s is realized with a maximum distance of 10cm. The average operation power consumption are 575μA and 3.2 mA for the internal and external circuit, respectively.