CMOS Analog Integrated Circuits

4

Bias and Current Reference Circuits

CONTENTS

4.1    Current mirrors

4.1.1    Simple current mirror

4.1.2    Cascode current mirror

4.1.3    Low-voltage active current mirror

4.2    Current and voltage references

4.2.1    Supply-voltage independent current reference

4.2.2    Bandgap references

4.2.2.1    Low-voltage bandgap voltage reference

4.2.2.2    Curvature-compensated bandgap voltage reference

4.2.3    Floating-gate voltage reference

4.3    Summary

4.4    Circuit design assessment

As the power supply is scaled down, the operation of analog circuits becomes difficult because the threshold voltage of MOS transistors and dc operating points are not scaling proportionally. The bias and current reference circuits should be designed to feature ...