CMOS Operational amplifier
AssigneeAT&T Laboratories
InventorsKyle L. Burson, Scott H. Early, Apparajan Ganesan
Life of this patent
Estimating the term…
Abstract
Two input stages (10,12) are interconnected so that their input common mode voltage ranges to one side of signal ground are combined to provide a common mode voltage range substantially equal to the supply voltage. One stage has N-channel differential input transistors (N1,N2), while the other stage has P-channel differential input transistors (P3,P4). The input current branches of the stages are interconnected by current mirror transistors (N6,N7) so that signal current is shared. The output (22) is taken from one branch of the N-type stage (10) and coupled to an output stage (24) with frequency compensation (C,R).
Claims12
An operational amplifier comprising:
- first and a second power supply voltage nodes;
- a first differential input stage connected between said supply voltage nodes and including first and second input current branches with one end connected to said first supply voltage node and the other end connected to one side of a first current source, the other side of said first current source being connected to said second supply voltage node;
- a second differential input stage connected between said supply voltage nodes, in parallel with said first stage, and including first and second input current branches with one end connected to said second supply voltage node and the other end connected to one side of a second current source, the other side of said second current source being connected to said first supply voltage node;
- first means coupled between said first branch of said first stage and said first branch of said second stage for establishing proportional currents in them;
- second means coupled between said second branch of said first stage and said second branch of said second stage for establishing proportional currents in them, and
- an output stage having an input node coupled to said second branch of said first stage.
Dependencies are inferred from the claim text.