Electrode assembly and handpiece with adjustable system impedance, and methods of operating an energy-based medical system to treat tissue

Electrode assemblies and handpieces for energy-based treatment systems that utilize an impedance assembly to facilitate impedance matching between the system and a patient. The electrode assembly and/or handpiece may include one or more circuit elements configured to introduce at least one supplemental impedance into an electrical circuit coupling the electrode assembly and handpiece. The supplemental impedance, which is related to the impedance of the treatment system and patient, is introduced when the electrode assembly is coupled with the handpiece.