Low-voltage wide-range built-in current sensing for system-on-chip applications

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 muW. The proposed circuit has been designed and simulated in 0.18-mum CMOS process with 1.8 V supply