A combination charging and telemetry circuit for use within an implantable device, such as a microstimulator, uses a single coil for both charging and telemetry. In accordance with one aspect of the invention, one or more capacitors are used to tune the single coil to different frequencies, wherein the coil is used for multiple purposes, e.g., for receiving power from an external source and also for the telemetry of information to and from an external source.