We propose a new implantable circuit for the internal Functional Electrical Stimulation (FES) of motor nerves for paraplegic people. The circuit is designed to deliver precise calibrated stimulation pulses to specific multipolar electrodes. Several original design features have been developed to respond to the particular specifications imposed by safety constraints. In particular, the DAC has been thought to be fully monotonic and the output stage to ensure a passive and secure discharge of the safety capacitor. Also some tricky features have been added in order to improve the classical charge pump that generates on-chip high voltage.