Switchable dual-coil communication circuitry for extending communication range in an implantable medical device system

A communications device useable in an implantable medical device system, comprising:

• a first resonant circuit having an inductive coil and a capacitor connected in series;
• a second resonant circuit having an inductive coil and a capacitor connected in series;
• control circuitry configured to issue at least one control signal indicating whether the communications device is to transmit data or receive data;
• and
• switching circuitry controlled by the at least one control signal, wherein the switching circuitry is configured to use only the first resonant circuit to transmit data, and wherein the switching circuitry is configured to couple the first and second resonant circuits to receive data.

An external controller for transmitting data to and receiving data from an implantable medical device, comprising:

• a first resonant circuit comprising a first capacitor and a first coil;
• a second resonant circuit comprising a second capacitor and a second coil;
• control circuitry configured to issue digital data to be transmitted and to receive digital data from the implantable medical device, and configured to issue at least one control signal indicating whether the external controller is to transmit data to or to receive data from the implantable medical device;
• and
• switching circuitry controlled by the at least one control signal, wherein the switching circuitry is configured to use only the first resonant circuit to transmit data at a first frequency, and wherein the switching circuitry is configured to connect the first and second resonant circuits in series to receive data at the first frequency.