Low voltage self cascode current mirror

Abstract

An integrated circuit is provided for sourcing a mirrored current into a high impedance output node. A load may be coupled to the output node, and the mirrored current may be derived proportional to or substantially equal to current forwarded from a reference current source. The integrated circuit, or current mirror, includes a pair of series-connected output transistors coupled between the output node and a reference terminal. One of the output transistors is dimensioned with a channel that is short enough to ensure the threshold voltage of that transistor is smaller than the threshold voltage of the other transistor having a longer channel. Thus, one transistor utilizes the benefits of high density integrated circuit manufacture and, more specifically, short channel effects arising from channel length less than, e.g., 1.0 microns. The difference in threshold voltages between the pair of output transistors, and mutually connecting gates of those transistors helps maximize the output impedance and voltage swing from the output node of the current mirror while minimizing voltage needed to operate the current mirror.

Dependencies are inferred from the claim text.