Differential amplifier with variable neutralization
AssigneeTexas Instruments Incorporated
InventorsKrishnanshu Dandu, Brian P. Ginsburg
Life of this patent
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Abstract
Disclosed examples include differential amplifier circuits and variable neutralization circuits for providing an adjustable neutralization impedance between an amplifier input node and an amplifier output node, including neutralization impedance T circuits with first and second impedance elements in series between the amplifier input and output, and a third impedance element, including a first terminal connected to a node between the first and second impedance elements, and a second terminal connected to a transistor. The transistor operates according to a control signal to control the neutralization impedance between the amplifier input node and the amplifier output node.
Claims20
An amplifier circuit comprising:
- a differential input that includes a first amplifier input and a second amplifier input;
- a differential output that includes a first amplifier output and a second amplifier output;
- a differential pair that includes:
- a first transistor that includes a gate coupled to the first amplifier input and a drain coupled to the second amplifier output;
- and
- a second transistor that includes a gate coupled to the second amplifier input and a drain coupled to the first amplifier output;
- a neutralization circuit that includes:
- a first input coupled to receive a first voltage control signal;
- and
- a first impedance element coupled between the first amplifier input and the first amplifier output, wherein the first impedance element is responsive to the first voltage control signal;
- and
- a control circuit that includes an output coupled to the first input of the neutralization circuit to provide the first voltage control signal.
An amplifier circuit comprising:
- a differential input that includes a first amplifier input and a second amplifier input;
- a differential output that includes a first amplifier output and a second amplifier output;
- a differential pair that includes:
- a first transistor coupled to the second amplifier output and that includes a gate coupled to the first amplifier input;
- and
- a second transistor coupled to the first amplifier output and that includes a gate coupled to the second amplifier input;
- a first impedance element coupled between the first amplifier input and the first amplifier output;
- a first impedance control transistor coupled to the first impedance element and that includes a gate;
- and
- a control circuit that includes a first output coupled to the gate of the first transistor to provide a first voltage control signal, wherein the control circuit is configured to provide the first voltage control signal in response to a temperature signal from a sensor.
An amplifier circuit comprising:
- first and second amplifier inputs;
- first and second amplifier outputs;
- a first adjustable impedance element coupled between the first amplifier input and the first amplifier output;
- a first impedance control transistor coupled to the first adjustable impedance element and that includes a gate;
- and
- a control circuit that includes a first output coupled to the gate of the first impedance control transistor to provide a first voltage control signal to control an impedance of the first adjustable impedance element between the first amplifier input and the first amplifier output.
Dependencies are inferred from the claim text.