In this paper, an energy harvesting system composed by a flexible thermoelectric generator (TEG) with a DC - DC converter is shown. The proposed generator has been produced by screen printing technology on 80μm thick common paper and thin Kapton foil and integrates about 280 thermocouples, for an output voltage of about 75mV with 5K of the thermal gradient, useful for wearable - oriented applications. To increase the voltage provided by TEG, a DC - DC converter is implemented in 65nm CMOS technology. It operates for an input voltage (Vjn) range from 80mV to 370mV. This converter achieves an automatic control based on pulse width modulation (PWM), that ensure 1V output voltage (VOUT), for the various input voltages. The peak efficiency is 73% at 370mV of input voltage.