CMOS voltage reference based on threshold voltage and thermal voltage

摘要

A fully CMOS based voltage reference circuit is presented in this paper. The voltage reference circuit uses the difference between gate-to-source voltages of two MOSFETs operating in the weak-inversion region to generate the voltage with positive temperature coefficient. The reference voltage can be obtained by combining this voltage difference and the extracted threshold voltage of a saturated MOSFET which has a negative temperature coefficient. This circuit, implemented in a standard 0.35-μm CMOS process, provides a nominal reference voltage of 1.361 V at 2-V supply voltage. Experimental results show that the temperature coefficient is 36.7 ppm/°C in the range from −20 to 100°C. It occupies 0.039 mm2 of active area and dissipates 82 μW at room temperature. With a 0.5-μF load capacitor, the measured noise density at 100 Hz and 100 kHz is 3.6 and respectively. Keywords Voltage reference - Threshold voltage - Weak-inversion