High swing CMOS cascode current mirror

Details

Inventors: Sooch, Navdeep S.;
Assignee: AT&T Bell Laboratories (Murray Hill, NJ)
Primary Examiner:
Assistant Examiner:
Attorney, Agent or Firm:

A CMOS cascode current mirror exhibits an input side voltage swing equal to V.sub.T +2V.sub.ON and provides virtually no mismatch between the input and output currents. A negative feedback loop (52) comprising a plurality of MOS transistors is utilized to provide the voltages necessary for good current matching (V.sub.T +2V.sub.ON, V.sub.T +V.sub.ON) and to maintain the transistors of the input circuit branch in their saturation region of operation. By maintaining the input transistors in saturation, the output current will track the input current, regardless of increases in ambient temperature or the value of threshold voltage V.sub.T.

DETAILED DESCRIPTION The problems associated with prior art current mirrors are addressed by the present invention which relates to a CMOS current mirror and, more particularly, to a CMOS cascode current mirror which provides a high input voltage swing.
It is an aspect of the present invention to provide a CMOS current mirror which exhibits an input voltage swing equal to V.
sub.
T +2V.
sub.
ON.
Another aspect of the present invention is to provide accurate matching between I.
sub.
REF and I.
sub.
OUT over a wide range of processing and temperature variations.
Other and further aspects of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.

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