Methods and devices for improved evoked response detection

An implantable medical device (IMD), comprising:

• a pacing capacitor;
• one or more voltage generators configured to produce a plurality of different voltages including a first voltage and a second voltage, the second voltage having a greater magnitude than the first voltage;
• a controller configured to control when the pacing capacitor is being charged using the first voltage, when the pacing capacitor is being charged using the second voltage, and when the pacing capacitor is being discharged to deliver a pacing pulse between anode and cathode electrodes of, or electrically coupled to, the IMD;
• a sensing circuit configured to sense a cardiac electrical signal;
• and
• an evoked response detector configured to determine, based on a portion of the cardiac electrical signal sensed by the sensing circuit following delivery of the pacing pulse, and following a charge period, whether an evoked response occurred in response to the pacing pulse;
• wherein the controller is configured to cause the pacing capacitor to be charged using the second voltage during a portion of the charge period, and to cause the pacing capacitor to be charged using the first voltage during another portion of the charge period;
• wherein the charge period, which is a period during which the pacing capacitor is charged following delivery of the pacing pulse, begins following the pacing pulse being delivered and ends prior to the evoked response detector being used to determine whether the evoked response occurred in response to the pacing pulse;
• and
• wherein the evoked response detector, or a portion thereof, can be implemented by the controller.