A bi-channel voltage regulator protecting smart cards against power analysis attacks

The bi-channel voltage regulator proposed in this paper has been specifically developed for smart cards. Its purpose is to protect the supplied system against power analysis attacks. It generates the internal power supply voltage from the external power supply voltage provided by card readers, while ensuring the uncorrelation between the external power supply current and the internal power supply current. The power supply current of an electronic system can be decomposed into a DC component, which contains little information, and an AC component, which handles considerably more. In order to reach a good compromise between regulation and security, while respecting the smart card stringent technological constraints, these two components are treated separately by a bi-channel power structure. The presented implementation has been simulated from the process parameters of a STMicroelectronics 0.18 upmum0.18,upmuhbox{m} CMOS technology. It provides a 1.8 V output voltage from a 2 to 5.5 V input voltage range. The structure has been sized to handle a 25 mA DC current while hiding a 20 MHz AC current presenting 75 mA peaks. Its estimated area is approximatively 0.8 mm²0.8,hbox{mm}^2.