Patent ID: 6977526

Claim:
A squeezable tail current source, comprising: a first transistor pair that replicates a main input transistor pair of a differential amplifier circuit, wherein both the first transistor pair and the main input transistor pair receive a common voltage input at their respective gates; a second transistor pair; a bias transistor; a first current source; a folding transistor; and a second current source that biases the folding transistor, wherein the first transistor pair, the second transistor pair, the bias transistor, and the first current source are configured such that current through the main input transistor pair is maintained as the common voltage input varies; and wherein the second current source and the folding transistor isolate the bias transistor and the second transistor pair from a drain voltage of the first transistor pair, thereby causing the first transistor pair and the main input transistor pair to have a common drain bias.