Differential amplifier offset adjustment
AssigneeIntel Corporation
InventorsBryan K. Casper, James E. Jaussi
Life of this patent
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Abstract
A differential amplifier includes a source coupled differential pair of transistors. A feedback loop detects the presence of an input referred offset in the differential amplifier and modifies a body bias voltage on at least one of the transistors in the differential pair. A comparator detects a differential output voltage when the differential input voltage is set to zero. In some embodiments, a charge pump in the feedback loop injects charge on the body of the transistor to modify the bias voltage. In other embodiments, a digital-to-analog converter receives a digital control word and produces a bias voltage on the body of the transistor.
Claims29
A circuit comprising:
- first and second transistors coupled as a differential pair, each of the first and second transistors having a gate, a source, a drain, and a body;
- and
- a capacitor coupled between the body and the source of the first transistor;
- wherein the body of the second transistor is coupled to the source of the second transistor.
A differential amplifier circuit comprising:
- a current source;
- a differential pair of transistors coupled to the current source, the differential pair of transistors including a first transistor and a second transistor;
- a comparator to compare a differential output voltage of the differential pair of transistors;
- and
- a body bias circuit coupled between the comparator and a body of the first transistor.
An integrated circuit comprising:
- an amplifier having an input stage that includes a differential pair of transistors, the differential pair of transistors including a first transistor having a first body and a second transistor having a second body;
- an offset detector coupled to the differential pair of transistors to detect an offset current;
- and
- a body bias circuit responsive to the offset detector to bias the first body.
A method comprising:
- setting gate nodes of a differential pair of transistors to a common potential;
- detecting which of the differential pair of transistors has a greater current passing therethrough;
- and
- modifying a body bias of at least one transistor of the differential pair.
An article comprising a machine-accessible media having associated data, wherein the data, when accessed, results in a machine performing:
- detecting an amplifier offset;
- and
- modifying a body bias of one transistor in a differential pair of transistors.
Dependencies are inferred from the claim text.