An improved implantable pulse generator (IPG) containing improved telemetry circuitry is disclosed. The IPG includes a telemetry coil within the conductive IPG case, not in the non- conductive header as is typical, which simplifies IPG design. The improved resonant circuit of which the coil is a part does not include a discrete tuning resistor with the coil, which tuning resistor was traditionally used to increase communication bandwidth of the coil to render it suitable for FSK telemetry. In lieu of the tuning resistor, the coil is intentionally inductively coupled to the case by positioning the coil a certain distance away from the case. Such coupling decreases the effective inductance and increases the effective series resistance in the improved resonant circuit, both of which increase the communication bandwidth. As such, suitable FSK telemetry can be achieved, even though the improved resonant circuit without the case would not on its own have suitable bandwidth.
