A low-voltage MOS cascode bias circuit for all current levels

In this paper, the author describes a simple low-voltage MOS cascode bias circuit that functions well at all current levels, ranging from weak inversion to strong inversion. He describes an approach to defining the onset of saturation that is generally useful from a bias-circuit design viewpoint and explains specifically how it was used in designing the low-voltage cascode bias circuit. The author discusses an efficient strategy for laying out the cell in the full-stacked style. He also presents experimental results from a version of the bias circuit that was fabricated in a 1.2-μm CMOS process