Pulse Position Modulation Telemetry Circuit for Implantable Microstimulator Using RF-Powering Coil
Publication Date: 2001-Aug-31
The IP.com Prior Art Database
A Pulse Position Modulation (PPM) telemetry system for use within small implantable electrical devices, such as a microstimulator, uses an existing RF powering coil and capacitor, to transmit data from the implantable device to an external device. The coil is disconnected from the capacitor, and the capacitor is charged from a power source within the microstimulator. At the correct time, the capacitor is connected to the RF powering coil, thereby allowing the capacitor to discharge through the coil, causing a pulse to be transmitted from the coil. Data may be encoded using pulses created in this manner by the temporal position of the pulses. In accordance with one aspect of the PPM telemetry system, applicable to implantable devices having an existing RF-powering coil through which primary or charging power is received, the existing RF-powering coil is used in a time-multiplexing scheme to provide both the receipt of the RF signal and the PPM telemetry transmission. Such time-multiplexing minimizes the number of components needed within the device, and thus allows the device to be packaged in a smaller housing, or frees up additional space within an existing housing for other circuit components. In accordance with another aspect of the PPM telemetry system, a PPM system may encode signals in either an analog fashion by continuously varying the time between pulses, or in a digital fashion by assigning one pattern to a "1", and another pattern to a "0". The PPM telemetry system is thus suitable for use within an implantable device, and is compact, and efficient.