Operational amplifier with constant transconductance bias circuit and method using the same
First Claim
1. An operational amplifier, comprising:
- a differential difference amplifier, having at least one first differential transistor pair and at least one second differential transistor pair; and
a constant transconductance bias circuit, electrically connected to the differential difference amplifier, outputting a first bias voltage to bias the at least one first differential transistor pair and outputting a second bias voltage to bias the at least one second differential transistor pair,wherein the first bias voltage and the second bias voltage are configured to maintain constant Gm of the differential difference amplifier,wherein the differential difference amplifier comprises;
at least one first bias transistor, coupled to the at least one first differential transistor pair, wherein a control terminal of the at least one first bias transistor receives the first bias voltage to bias the at least one first differential transistor pair; and
at least one second bias transistor, coupled to the at least one second differential transistor pair, wherein a control terminal of the at least one second bias transistor receives the second bias voltage to bias the at least one second differential transistor pair.
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Abstract
An operational amplifier with a constant transconductance bias circuit and a method thereof are introduced. The operational amplifier includes a differential difference amplifier and the constant transconductance bias circuit. The differential difference amplifier has at least one first differential transistor pair and at least one second differential transistor pair. The constant transconductance bias circuit is electrically connected to the differential difference amplifier, and configured to output a first bias voltage to bias the at least one first differential transistor pair and output a second bias voltage to bias the at least one second differential transistor pair. The first bias voltage and the second bias voltage are configured to maintain constant transconductance of the differential difference amplifier.
8 Citations
18 Claims
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1. An operational amplifier, comprising:
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a differential difference amplifier, having at least one first differential transistor pair and at least one second differential transistor pair; and a constant transconductance bias circuit, electrically connected to the differential difference amplifier, outputting a first bias voltage to bias the at least one first differential transistor pair and outputting a second bias voltage to bias the at least one second differential transistor pair, wherein the first bias voltage and the second bias voltage are configured to maintain constant Gm of the differential difference amplifier, wherein the differential difference amplifier comprises; at least one first bias transistor, coupled to the at least one first differential transistor pair, wherein a control terminal of the at least one first bias transistor receives the first bias voltage to bias the at least one first differential transistor pair; and at least one second bias transistor, coupled to the at least one second differential transistor pair, wherein a control terminal of the at least one second bias transistor receives the second bias voltage to bias the at least one second differential transistor pair. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for biasing a differential difference amplifier having at least one first differential transistor pair, at least one second differential transistor pair, at least one first bias transistor and at least one second bias transistor, the method comprising:
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generating a first bias voltage and a second bias voltage; and outputting the first bias voltage to bias the at least one first differential transistor pair and the second bias voltage to bias the at least one second differential transistor pair; wherein the first bias voltage and the second bias voltage are configured to maintain constant transconductance of the differential difference amplifier, wherein the at least one first bias transistor is coupled to the at least one first differential transistor pair, a control terminal of the at least one first bias transistor receives the first bias voltage to bias the at least one first differential transistor pair, the at least one second bias transistor is coupled to the at least one second differential transistor pair, and a control terminal of the at least one second bias transistor receives the second bias voltage to bias the at least one second differential transistor pair. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification