Design Of A Boost DC-DC Converter With Ultra Low Power Consumption And Wide Input Voltage

In recent years,with the rapid growth of wearable devices,Internet of things and other markets,higher requirements are put forward for DC-DC converters,which are widely used in them,promoting the development of DC-DC in the direction of miniaturization,high efficiency and low cost.In this thesis,we design a boost DC-DC converter with 1.5 μA quiescent current.Also,the input voltage of the converter is as low as 0.7 V,and the output voltage is adjustable.All the characteristics make it have great advantages in low power applications.The hysteresis current mode modulation is adopted for the converter,and the control signal of the power MOSFETs are generated by the full-wave inductor current sensing signal.At the same time,the slope compensation circuit and clock signal are not needed for the hysteresis current mode modulation.When the load is light,the system automatically enters the burst mode.In the burst mode,most circuits of the system are turned off to achieve higher efficiency.Also,we propose a novel low-voltage start circuit.When the input voltage is 0.7 V,the chip can work normally and the starting process is smooth.At the same time,the converter includes bypass mode and down mode.When the input voltage is higher than the desired output,the converter can also work normally.That makes the chip available in more applications.For the implementation of circuits,we establish the small signal model of the control loop of the boost converter with hysteresis current mode modulation and design the compensation network,firstly.The system level simulation is carried out with Simulink.Then,based on HHGrace 0.11 μm CMOS process,we propose the transistor-level circuits of the system and optimize the parameters according to the simulation results.The simulation results show that the chip has an input voltage range of 0.7 V-5.5 V and an output voltage of 1.8 V-5 V.The quiescent current of the chip is 1.5 μA and the maximum inductor current is 1 A.In normal operation mode,the output voltage ripple is less than 10 m V;in burst mode,the output voltage ripple is approximately 2% of the output voltage.In the full load,the chip has high power efficiency.When the load is 10 μA,the power efficiency is more than 70%;when the load is100 m A,the power efficiency of the system can reach 95%.