Reference buffer with multiple gain stages for large, controlled effective transconductance
First Claim
1. A reference buffer amplifier comprising:
- a transconductance amplifier including a voltage input, received on an input terminal, and a current output, provided on an output terminal, the output terminal connected in feedback to the input terminal, the transconductance amplifier including;
a plurality of voltage gain stages connected in cascade;
at least one transconductance stage connected to a last-connected of the plurality of voltage gain stages; and
a load capacitor, that controls a bandwidth of the reference buffer, one terminal of which is connected to the output terminal of the transconductance amplifier and another terminal of which is connected a node external to the transconductance amplifier.
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Accused Products
Abstract
A reference buffer suitable for driving switched-capacitor or resistive load circuits provides a very low output impedance. The reference buffer utilizes an amplifier with a very large and controlled transconductance configured in feedback and compensated by a load capacitance. Cascaded gain stages are used to provide a large, controlled transconductance. In one embodiment, a reference buffer amplifier includes a plurality of voltage gain amplifiers connected in cascade and at least one transconductance amplifier connected to a last-connected of the plurality of voltage gain amplifiers. The amplifier may further include at least one current mirror amplifier connected to the at least one transconductance amplifier. In another embodiment, the reference buffer amplifier includes at least one transconductance amplifier and at least one current mirror amplifier cascade-connected to the at least one transconductance amplifier. The amplifiers can be differential or single-ended.
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Citations
15 Claims
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1. A reference buffer amplifier comprising:
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a transconductance amplifier including a voltage input, received on an input terminal, and a current output, provided on an output terminal, the output terminal connected in feedback to the input terminal, the transconductance amplifier including; a plurality of voltage gain stages connected in cascade; at least one transconductance stage connected to a last-connected of the plurality of voltage gain stages; and a load capacitor, that controls a bandwidth of the reference buffer, one terminal of which is connected to the output terminal of the transconductance amplifier and another terminal of which is connected a node external to the transconductance amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A reference buffer amplifier comprising:
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a transconductance amplifier including a voltage input received on an input terminal and a current output provided on an output terminal, the output terminal connected in feedback to the input terminal, the transconductance amplifier including; a voltage gain stage coupled to the input; at least one transconductance stage connected to an output of the voltage gain stage; a plurality of current gain stages cascade-connected to an output of a last connected of the at least one transconductance stage; and a load capacitor, that controls a bandwidth of the reference buffer, one terminal of which is connected to the output terminal of the transconductance amplifier and another terminal of which is connected a node external to the transconductance amplifier. - View Dependent Claims (10, 11, 12)
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13. A reference buffer comprising:
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at least one transconductance amplifier; and at least one current gain amplifier cascade-connected to the at least one transconductance amplifier; wherein the at least one current gain amplifier includes a current mirror having positive feedback to increase a current gain of the current gain amplifier without increasing a quiescent power of the current gain amplifier.
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14. A reference buffer amplifier comprising:
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a differential transconductance amplifier including a voltage input received on an input terminal and a current output provided on first and second output terminals, at least one of the first and second output terminals connected in feedback to the input terminal, the transconductance amplifier including; a plurality of voltage gain stages connected in cascade; at least one transconductance stage connected to a last-connected of the plurality of voltage gain stages; and a load capacitor, connected between the first and second output terminals of the transconductance amplifier, that controls a bandwidth of the reference buffer.
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15. A reference buffer amplifier comprising:
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a transconductance amplifier including a voltage input received on an input terminal and a current output provided on first and second output terminals, at least one of the first and second output terminals connected in feedback to the input terminal, the transconductance amplifier including; a voltage gain stage coupled to the input; at least one transconductance stage connected to the output of an voltage gain stage; a plurality of current gain stages cascade-connected to an output of a last connected of the at least one transconductance stage; and a load capacitor, connected between the first and second output terminals of the transconductance amplifier, that controls a bandwidth of the reference buffer.
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Specification