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This paper presents a low-voltage on-chip current sensor that is well suited for cryptosystem applications, as well as testing, and battery lifetime improvement. The sensing method is based on an improved current mirror with a compensating circuit and a dynamic control loop that provides wide range and high linearity while introducing a small voltage drop. The voltage drop across the sensor remains below 60 mV (less than a single V DSsat ) for a wide current range of 0.5 to 10 mA and the linearity is better than 98%. The total power dissipation for 5 mA is 700 µW. The proposed circuit has been designed and simulated in 0.18-µm CMOS process with 1.8 V supply.

This paper presents a control circuit which regulates the current consumption of integrated circuits using current injection and voltage scaling techniques. The control circuit can be integrated with smart cards as a countermeasure against power analysis attacks and electromagnetic emanation analysis attacks. We have designed the proposed circuit in 0.18 μm CMOS technology at 1.8 V power supply. The simulation results show that the circuit controls the current through the power supply pin of a model of a smart card microcontroller and attenuates the peak-to-peak current variations by 95%. The power dissipation overhead of the control circuit is less than 20% of the original power dissipation of the smart card microcontroller. Comparing the layout area of the proposed circuit with that of an ASIC 3-DES algorithm in the same technology shows that the control circuit only constitutes 4% of the cryptographic processor. The proposed circuit proves to be especially useful for smart cards and small portable devices, where power dissipation and chip area are critical.