A 300 nW, 7 ppm/°C CMOS voltage reference circuit based on subthreshold MOSFETs

An ultra-low power CMOS voltage reference circuit has been fabricated in a 0.35-mum standard CMOS process. The circuit generates a reference voltage based on threshold voltage of a MOSFET at absolute zero temperature. Theoretical analyses and experimental results showed that the circuit generates a quite stable reference voltage of 745 mV on average. The temperature coefficient and line sensitivity of the circuit were 7 ppm/degC and 20 ppm/V, respectively. The power supply rejection ratio (PSRR) was -45 dB at 100 Hz. The circuit consists of subthreshold MOSFETs with a low-power dissipation of 0.3 muW or less and a 1.5-V power supply. Because the circuit generates a reference voltage based on threshold voltage of a MOSFET in an LSI chip, it can be used as an on-chip process monitoring circuit and as a part of the on-chip process compensation circuit systems.