A driver circuit is configured as a frequency compensated differential amplifier having one input coupled to a first data signal and a second input coupled to a second data signal. The implantable lead may be inserted through the tissue with minimal expansion of the penetration tunnel and attached to the tissue being stimulated with minimal efforts or apparatus. The sensor includes two convex transparent parts collecting light each toward a respective photodiode, the transparent parts being separated by an opaque portion. The invention takes advantage of existing sensor technologies and develops a computational framework for their fusion for the prediction of a dependency, which controls operation of the compressor. By adapting the properties, dimensions andor orientation of the faces of the wavelength converting member according to the invention, a desirable light distribution from the light-emitting arrangement is achieved. The system includes a component cover with a detection portion; a sensor adapted to detect the presence of the detection portion in the component cover; and a processor able to receive information from the sensor and to prepare the mobile device for power loss.