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US 6,377,121 B1Granted
Dynamic cascoding technique for operational amplifiers
AssigneeIntel Corporation
InventorHari Giduturi
Life of this patent
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Abstract
An apparatus for a differential amplifier with dynamic cascodes. The apparatus of one embodiment comprises a dynamic cascode bias generator. A first and second cascode transistors are coupled to the generator. A differential pair is coupled to the cascode transistors. The differential pair comprises of a first input transistor to receive an inverting input and a second input transistor to receive a non-inverting input.
Claims21
An apparatus comprising:
- a dynamic cascode bias generator;
- a first and second cascode transistors coupled to said dynamic cascode bias generator, wherein said dynamic cascode bias generator generates an output voltage to said first and second cascode transistors, said output voltage to be a fixed value in a first mode, and said output voltage to increase towards upper range of a power supply voltage rail in a second mode;
- a differential pair coupled to said cascode transistors, said differential pair comprising of a first input transistor to receive an inverting input and a second input transistor to receive a non-inverting input;
- and
- a common mode input signal coupled to said second input transistor, said common mode input signal to vary from a first voltage level to a second voltage level.
2 more elements
An operational amplifier comprising:
- a dynamic cascode bias generator;
- an N type differential amplifier coupled to said dynamic cascode bias generator, said N type differential amplifier comprising:
- a first and second N type cascode transistors coupled to said dynamic cascode bias generator;
- and
- an N type differential pair coupled to said first and second N type cascode transistors, said N type differential pair comprising of a first N type input transistor to receive an inverting input and a second N type input transistor to receive a non-inverting input;
- and
- a P type differential amplifier coupled to said dynamic cascode bias generator, said P type differential amplifier comprising:
- a first and second P type cascode transistors coupled to said dynamic cascode bias generator;
- and
- a P type differential pair coupled to said first and second P type cascode transistors, said P type differential pair comprising of a first P type input transistor to receive said inverting input and a second P type input transistor to receive said non-inverting input.
7 more elements
A method comprising:
- receiving a common mode input voltage;
- determining whether said input voltage is within a cascoding range;
- and dynamically generating a cascode bias voltage, said bias voltage having a fixed voltage value if said input voltage is within said cascoding range, said bias voltage having a varying voltage value that approaches a supply rail if said input voltage is outside said cascoding range.
Dependencies are inferred from the claim text.