A tissue ablation apparatus is disclosed that includes an elongate, flexible device operable to be percutaneously place in vasculature of a patient. The device has an array of 8 or more tissue ablation elements carried on a flexible circuit substrate located at a distal end portion. A cable is also included that has a number of electrical conductors insulated from one another that are each electrically coupled to a different one of the elements. One or more connectors are electrically coupled to the cabling at a proximal end portion of the device.