A 6.6‐nA, 3.6‐nW CMOS Current Reference With 0.4‐V Supply Voltage

ABSTRACT This paper presents an all‐MOSFET nanoampere (nA) current reference with a wide operating temperature range able to operate at a supply voltage as low as 0.4 V for ultra‐low power applications. The temperature‐compensated current is generated by combining two currents with opposite temperature coefficients (TCs), which are derived from two NMOS transistors biased with different complementary‐to‐absolute‐temperature (CTAT) gate voltages. Self‐biased self‐cascode MOSFET (SBSCM) stages operating in the subthreshold region are utilized as the slope‐adjustable linear CTAT voltage generators to achieve both low‐power and low‐voltage operation. Designed in a 130‐nm CMOS process with an active area of 0.0021 mm 2 , the proposed current reference achieves an average untrimmed TC of 308 ppm/°C over −40°C to 120°C while generating an output reference current of 6.6 nA. Post simulation results show that the power consumption is only 3.68 nW at the minimum supply voltage at room temperature.