Circuitry to assist with neural sensing in an implantable stimulator device in the presence of stimulation artifacts

An implantable medical device, comprising:

• a first electrode node coupleable to a first electrode configured to make electrical contact with a patient's tissue, and a second electrode node coupleable to a second electrode configured to make electrical contact with the patient's tissue, wherein the first electrode node is configured to receive via the first electrode a tissue signal from the patient's tissue;
• an amplifier with a first input connected to the first electrode node and with a second input connected to the second electrode node, wherein the amplifier produces an amplifier output indicative of the tissue signal;
• first comparator circuitry configured to receive the first input and to generate a first output indicating whether the first input meets an input requirement of the amplifier;
• second comparator circuitry configured to receive the second input and to generate a second output indicating whether the second input meets an input requirement of the amplifier;
• and
• first logic circuitry configured to receive the first output and the second output and to generate an enable signal, wherein the enable signal indicates whether the amplifier output indicative of the tissue signal is valid or invalid.