Low-voltage Low-power High Precision Voltage Reference Research And Design Under Nanometer Process

CMOS scaling is the engine of the continuous improvement of digital applications. As device dimension becomes smaller and smaller, integrated circuit manufacturing costs, working voltage and power consumption become lower and lower. As nanometer process grows up, the development trend of low-voltage low-power design is becoming faster and faster. Voltage reference is indispensible in analog and mixed circuit design. It could provide a stable and accurate voltage for other systems. The research of voltage reference is of great significance especially under the trend of low-voltage low-power IC design.Firstly, the background and meaning of research about low-voltage low-power reference are introduced. Briefly analyze the 12 bit 200Msps Current-Steering DAC which includes this voltage reference design, introduce the types of C-S DAC and the function of voltage reference in DAC. Also identify the specification of the low-voltage low-power reference design.Then, all aspects of voltage reference are summarized in detail. Traditional bandgap reference is introduced and some difficulties of IC design under process level are analyzed within low-voltage low-power design standard. Also some novel low power reference structures are discussed.Then, the working principle of MOSFET is described with combination of structure about MOSFET. Threshold voltage of MOSFET and its temperature property are elaborated. The I-V property of MOSFET which works in the subthreshold region is also described. A CTAT voltage circuit which has a second-order temperature characteristic is designed based on the subthreshold region MOSFET. A PTAT voltage circuit is also designed.Finally, a novel low-voltage low-power high accuracy voltage reference is designed based on the current mirror technology and MOSFET which works in subthreshold region. Theoretical analysis and formula derivation of each block in this circuit are deduced. Output voltage which has second-order temperature compensation is come out with Hspice simulation under 55 nm process. Simulation results show that, an output voltage of 272 mV is got with 1.2V power supply. The output voltage has a temperature coefficient of 5.9 ppm/℃, and maximum TC of 13ppm/℃ under each process corners, working current 8.68 uA and power consumption 10.4 μW. The deviation factor is as low as 1.1% during Monte Carlo simulation.