Low power CMOS temperature protection sensor for smart cards

In this paper, it is presented the design of a low power temperature sensor for the protection of smart cards from security attacks at the corners of their operating temperature range. The attacks usually use failure generation techniques for abnormal environmental conditions. They normally result in malfunctions in the smart card processor, allowing additional access to information to happen. The purpose of this design is to effectively protect the chip of smart cards from this art of security tampering for the temperature range -20 °C to 120 °C with a small area and low power consumption circuit. The sensor is designed in Cadence and TSMC using the System on a Chip (SoC) concept employing a standard 0.090 μm CMOS technology and operates on a power supply voltage of 1.2 V. It is based on a circuit with two MOS transistors and only one PNP bipolar transistor for producing a Complementary to Absolute Temperature (CTAT) voltage. The obtained results for the temperature protection at the corners of a -40 °C to 140 °C temperature range and V_dd = 1.2V ± 10%, show an excellent performance for the sensor; the Power Supply Rejection Ratio (PSRR) -62 dB in the worst case and a hysteresis corner 5mV. This new circuit design can effectively work as an excellent protector against security tampering to smart cards.