As an essential building block in integrated circuits and systems, bandgap voltage reference plays an important role to provide a reference voltage which is independent of temperature, supply voltage and process variation to the whole system. As the low power Internet-of-things (IoT) applications become popular, ultra-low power bandgap voltage reference attracts more attention in recent research. In most voltage references, resistor is a common choice to generate proportional-to-absolute-temperature (PTAT) current and PTAT voltage. In order to reduce the current on the resistors, large resistance values are used which will increase the silicon area and cost. Thus, ultra-low power resistor-less bandgap voltage reference is indispensable for the low-power IoT devices for its low p...[ Read more ]

As an essential building block in integrated circuits and systems, bandgap voltage reference plays an important role to provide a reference voltage which is independent of temperature, supply voltage and process variation to the whole system. As the low power Internet-of-things (IoT) applications become popular, ultra-low power bandgap voltage reference attracts more attention in recent research. In most voltage references, resistor is a common choice to generate proportional-to-absolute-temperature (PTAT) current and PTAT voltage. In order to reduce the current on the resistors, large resistance values are used which will increase the silicon area and cost. Thus, ultra-low power resistor-less bandgap voltage reference is indispensable for the low-power IoT devices for its low power consumption and small chip area.

In this thesis, two designs of ultra-low power resistor-less bandgap voltage reference are presented. The first design is an 18-nA ultra-low current resistor-less bandgap reference based on differential PTAT voltage generator with proposed voltage duplicator. This design can work at 2.8 V – 4.5 V high voltage supply and can be applied in the energy harvesting systems that use lithium-ion (Li-ion) battery as an intermediate energy storage. The average temperature coefficient is 65 ppm/ ºC and line regulation is 0.112 %/V. Fabricated in 0.35-μm process, the chip active area is 0.042 mm². The second design is an 8-nW resistor-less bandgap reference based on a single-branch floating PTAT voltage which can work at 1.4 V- 3.3 V supply voltage. The average temperature coefficient is 69 ppm/ ºC and the line regulation is 0.019 %/V. Fabricated in 0.13-μm process, the chip active area is 0.017 mm².