High gain, high bandwidth, fully differential amplifier
First Claim
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1. An amplifier comprising:
- a first differential pair comprising first and second transistors;
a first cascode transistor coupled to the first transistor of the first differential pair to form a folded-cascode pair, the first cascode transistor having a first terminal and a second terminal;
a first current mirror comprising first and second transistors to bias currents in the first and second transistors of the first differential pair, wherein the first transistor of the first current mirror is coupled to bias current in the first cascode transistor; and
a first auxiliary amplifier to provide negative feedback from the first terminal of the first cascode transistor to the second terminal of the first cascode transistor.
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Abstract
A high gain, high bandwidth, fully differential CMOS amplifier.
16 Citations
15 Claims
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1. An amplifier comprising:
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a first differential pair comprising first and second transistors;
a first cascode transistor coupled to the first transistor of the first differential pair to form a folded-cascode pair, the first cascode transistor having a first terminal and a second terminal;
a first current mirror comprising first and second transistors to bias currents in the first and second transistors of the first differential pair, wherein the first transistor of the first current mirror is coupled to bias current in the first cascode transistor; and
a first auxiliary amplifier to provide negative feedback from the first terminal of the first cascode transistor to the second terminal of the first cascode transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An amplifier to provide a first output voltage indicative of a differential of first and second input voltages, the operational amplifier comprising:
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a first input node at the first input voltage;
a second input node at the second input voltage;
a first output node at the first output voltage;
a first differential pair comprising first and second transistors;
a first cascode transistor coupled to the first transistor of the first differential pair to form a folded-cascode pair;
a second differential pair comprising first and second transistors;
wherein the first transistors of the first and second differential pairs are coupled to the first input node to be responsive to the first input voltage, and the second transistors of the first and second differential pair are coupled to the second input node to be responsive to the second input voltage;
a second cascode transistor coupled to the first transistor of the second differential pair to form a folded-cascode pair;
a first current mirror comprising first and second transistors to sink, respectively, current from the first and second transistors of the first differential pair, wherein the first transistor of the first current mirror is coupled to sink current from the first cascode transistor;
a second current mirror comprising first and second transistors to source, respectively, current to the first and second transistors of the second differential pair, wherein the first transistor of the second current mirror is coupled to source current to the second cascode transistor; and
a first auxiliary amplifier to control current flow in the first cascode transistor by negative feedback, and to control current flow in the second cascode transistor by negative feedback;
wherein the first and second cascode transistors are coupled to the first output node to provide the first output voltage. - View Dependent Claims (9, 10)
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11. An amplifier comprising:
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a first differential pair comprising first and second unipolar transistors of a first carrier type, each having a drain, a gate, and a source;
a first cascode unipolar transistor of a second carrier type complementary to the first carrier type, having a gate, having a drain, and having a source connected to the drain of first transistor of the first differential pair;
a first current mirror comprising first and second unipolar transistors of the second carrier type, each having a gate, a drain, and a source, wherein the drain of the first transistor of the first current mirror is connected to the drain of the first transistor of the first differential pair, and wherein the drain of the second transistor of the first current mirror is connected to the drain of the second transistor of the first differential pair;
a second differential pair comprising first and second unipolar transistors of the second carrier type, each having a drain, a gate, and a source;
a second cascode unipolar transistor of the first carrier type, having a gate, having a drain, and having a source connected to the drain of first transistor of the second differential pair;
a second current mirror comprising first and second unipolar transistors of the first carrier type, each having a gate, a drain, and a source, wherein the drain of the first transistor of the second current mirror is connected to the drain of the first transistor of the second differential pair, and wherein the drain of the second transistor of the second current mirror is connected to the drain of the second transistor of the second differential pair;
a third cascode unipolar transistor of the second carrier type, having a gate, having a drain, and having a source connected to the drain of second transistor of the first differential pair;
a fourth cascode unipolar transistor of the first carrier type, having a gate, having a drain, and having a source connected to the drain of second transistor of the second differential pair;
a first auxiliary amplifier to provide feedback from the source of the first cascode transistor to the gate of the first cascode transistor, and to provide feedback from the source of the second cascode transistor to the gate of the second cascode transistor; and
a second auxiliary amplifier to provide feedback from the source of the third cascode transistor to the gate of the third cascode transistor, and to provide feedback from the source of the fourth cascode transistor to the gate of the fourth cascode transistor. - View Dependent Claims (12, 14, 15)
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13. An amplifier comprising:
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a first differential pair;
a first current mirror to sink current from the first differential pair;
a second differential pair;
a second current mirror to source current to the second differential pair;
a first cascode transistor connected to the first differential pair;
a second cascode transistor connected to the second differential pair;
a third cascode transistor connected to the first differential pair;
a fourth cascode transistor connected to the second differential pair;
a first auxiliary amplifier to provide feedback to control current in the first and second cascode transistors; and
a second auxiliary amplifier to provide feedback to control current in the third and fourth cascode transistors.
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Specification