Patent ID: 8116865

Claim:
An implantable medical device for delivering electric therapy to a heart of a patient, comprising: a defibrillation voltage source; a first switch circuit comprising a first node and a second node, the first node coupled to a first terminal of the voltage source; a bridge circuit coupled to the second node and to a second terminal of the voltage source, the bridge circuit configured to connect to a first electrode and a second electrode, the first and second electrodes configured to be implanted in or near the heart; wherein the bridge circuit is configured to deliver a first polarity energy to the heart using the first and second electrodes in a first mode, and the bridge circuit is configured to deliver an opposite polarity energy to the heart using the first and second electrodes in a second mode; and wherein closing the first switch circuit comprises charging a drive voltage capacitor coupled to a gate and an emitter of a transistor, the transistor comprising a collector coupled to the first terminal of the voltage source and the emitter coupled to the bridge circuit, and causing the drive voltage capacitor to provide a voltage to turn on the transistor.