LAUSR

This brief presents a CMOS voltage reference for ultra-low-power applications, such as in implementable medical devices and energy harvesting-based wireless sensor nodes. In these applications, excellent capabilities to reject interference from power sources and work in low voltage to extend survival periods are critical for the voltage references. A transistor size-ratio determined current generator with high process and voltage independence is implemented by two same-threshold-voltage NMOS transistors, hence obtaining the precise reference voltage with an active load. The proposed circuit is fabricated in a standard 0.18- ${\mu }\text{m}$ CMOS process. Measurement results show that the prototype design provides a 210-mV reference with only 0.027% line sensitivity with a supply voltage from 1.8 V down to 0.4 V. The power supply ripple rejection at 10 Hz, 1 KHz, and 1 MHz is −59, 47, and 53 dB, respectively. The temperature coefficient is 82 ppm/°C in the temperature range from −40°C to +140 °C. Furthermore, the power consumption is only 9.6 nW at room temperature and the active area is 0.021 mm².