An Ultralow Power Subthreshold CMOS Voltage Reference Without Requiring Resistors or BJTs

This brief presents a novel ultralow power CMOS voltage reference (CVR) with only 4.6-nW power consumption. In the proposed CVR circuit, the proportional-to-absolute-temperature voltage is generated by feeding the leakage current of a zero-V-gs nMOS transistor to two diode-connected nMOS transistors in series, both of which are in subthreshold region; while the complementary-to-absolute-temperature voltage is created by using the body diodes of another nMOS transistor. Consequently, low-power operation can be achieved without requiring resistors or bipolar junction transistors, leading to small chip area consumption. The proposed CVR circuit is fabricated in a standard 0.18-mu m CMOS process. Measurement results show that the prototype design is capable of providing a 755 mV typical reference voltage with 34 ppm/degrees C from -15 degrees C to 140 degrees C. Moreover, the typical power consumption is only 4.6 nW at room temperature and the active area is only 0.0598 mm(2).