Fully-differential receiver for receiving conducted communication signals

A fully-differential receiver for use in an implantable medical device (IMD) and configured to receive conducted communication signals that are transmitted by another IMD or an external device, the fully-differential receiver comprising:

• a first comparator including a differential pair of inputs and a first output;
• a second comparator including a differential pair of inputs and a second output, wherein the differential pair of inputs of the second comparator are coupled to the differential pair of inputs of the first comparator such that the differential pair of inputs of the first and second comparators are coupled to one another;
• and
• the differential pair of inputs of each of the first and second comparators include a respective non-inverting (+) input and a respective inverting (−) input;
• the non-inverting (+) input of the first comparator is coupled to the inverting (−) input of the second comparator;
• and
• the inverting (−) input of the first comparator is coupled to the non-inverting (+) input of the second comparator;
• wherein the first comparator is configured to produce an output pulse at the first output when a voltage potential difference between the non-inverting (+) input and the inverting (−) input of the first comparator exceeds a first offset and is positive relative to a common mode voltage of the fully-differential receiver;
• and
• wherein the second comparator is configured to produce an output pulse at the second output when a voltage potential difference between the non-inverting (+) input and the inverting (−) input of the second comparator exceeds a second offset and is negative relative to the common mode voltage of the fully-differential receiver.

An implantable medical device (IMD) that is configured to communicate with at least one of another IMD or an external device using conducted communication signals, the IMD comprising:

• at least two electrodes;
• a fully-differential receiver having a pair of inputs and a pair of outputs, the pair of inputs of the fully-differential receiver coupled to a pair of the at least two electrodes, the pair of outputs of the fully-differential receiver including a first output and a second output;
• a logic detector having a pair of inputs and an output, the pair of inputs of the logic detector coupled to the pair of outputs of the fully-differential receiver;
• a controller including an input coupled to the output of the logic detector, wherein the controller is configured to decode pulses received from the logic detector;
• and
• a battery configured to power components of the IMD, including the fully-differential receiver, the logic detector, and the controller;
• wherein the fully-differential receiver is configured to
• produce a positive detection pulse (DETP) at the first output, of the pair of outputs, in response to a positive portion of a received biphasic pulse, and
• produce a negative detection pulse (DETN) at the second output, of the pair of outputs, in response to a negative portion of the received biphasic pulse.

A method for use with a fully-differential receiver of an implantable medical device (IMD), wherein the fully-differential receiver is powered by a battery of the IMD, the method comprising:

• operating a fully-differential receiver in accordance with a first mode by biasing each of a plurality of active stages of the fully-differential receiver using a respective bias current, wherein during the first mode a wakeup signal is monitored for within a first frequency range;
• in response to receiving the wakeup signal while the fully-differential receiver is operating in the first mode, changing from operating the fully-differential receiver in accordance with the first mode to operating the fully-differential receiver in accordance with a second mode by increasing each respective bias current used to bias each of the plurality of active stages of the fully-differential receiver, wherein during the second mode one or more message content pulses are received within a second frequency range;
• and
• changing from operating the fully-differential receiver in accordance with the second mode back to operating the fully-differential receiver in accordance with the first mode;
• wherein the second frequency range is higher than the first frequency range;
• and
• wherein the second mode drains more current and thereby more power from the battery compared to the first mode.