50 nA, 1 V nanowatt resistor-free compact CMOS current references

This paper presents a comparison between resistor-free nanowatt CMOS current references based on different topologies. All of these current references are designed to generate 50 nA currents under 1 V power supply. Designed in a standard 0.35 μm CMOS process, these current references showed low sensitivity with respect to the variations from power supply, fabrication process and temperature. EKV 2.0 MOS model which is able to provide continuous equation over different inversion levels (weak, moderate, and strong) is used in the process of analyzing these current references. Simulation results for these current references showed a max temperature coefficient of 0.07 %/°C over a temperature range of -40°C to 125°C and a minimum power supply as low as 0.75 V.