This paper describes the design and operation of a high output impedance tissue current driver circuit, for use in medical electronics, such as Electrical Impedance Tomography (EIT). This novel architecture was designed for implementation in bipolar technology, to meet the specifications for EIT, namely operating frequency range 10 kHz–1 MHz with a target output resistance of 16 MW. Simulation results are presented, showing that the current source more than met the minimum specification for EIT