In one embodiment, the present invention provides an implantable stimulation device that includes output current sources and/or sinks configured to provide an output current for a load (i.e., tissue). The output path of the output current source or sink comprises a transistor which operates in a linear...http://www.google.co.uk/patents/US7539538?utm_source=gb-gplus-sharePatent US7539538 - Low power loss current digital-to-analog converter used in an implantable pulse generator
