1. A reference voltage electronic circuit comprising: a capacitive element having a floating gate for non-volatile and non-modifiable storage of a constant charge, a tunable transformation module having an input being coupled to the capacitive element providing a constant voltage corresponding to the constant charge, the transformation module providing tunable transformation of the constant voltage to an output reference voltage, a control loop for tuning the transformation module by means of an external calibration module making use of a high precision reference voltage source.