1. $^{1}$Photonlab, Istituto Superiore Mario Boella (ISMB), Torino, Italy
2. Photonlab, Ist. Superiore Mario Boella (ISMB), Torino, Italy
3. $^{2}$Dipartimento di Elettronica, Politecnico di Torino, Torino, Italy
4. $^{3}$Fraunhofer Institute for Integrated Circuits, Erlangen, Germany
5. Fraunhofer Inst. for Integrated Circuits, Erlangen, Germany