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US 6,972,624 B1Granted
Low-voltage high dynamic range variable-gain amplifier
AssigneeLinear Technology Corporation
InventorPetrus Martinus Stroet
Life of this patent
Estimating the term…
Abstract
Circuits and methods for providing a variable gain while powered from a low-voltage supply. In a specific embodiment, an input signal is converted to a current by an emitter-degenerated pair. A portion of the input current is discarded, while the remainder is variably steered between a shunt stage or an AC ground such as VCC. The output of the shunt stage is buffered by a high speed output, the bandwidth of which is increased by feed-forward capacitors. This arrangement may be optionally repeated for additional gain.
Claims26
A variable-gain amplifier comprising:
- a variable-gain voltage-to-current converter stage comprising:
- a grounded emitter-degenerated pair coupled to an input port, the grounded emitter-degenerated pair having first and second devices that are coupled in a common-base configuration;
- and
- a transistor quad coupled between the emitter grounded emitter degenerated pair and a first supply terminal.
1 more element
A variable-gain amplifier comprising:
- a variable-gain voltage-to-current converter stage comprising:
- a grounded emitter-degenerated pair coupled to an input port and configured to convert an input signal at the input port to a first differential current;
- a device that is coupled to form a current mirror with the grounded emitter-degenerated pair;
- and
- a transistor quad coupled to the grounded emitter degenerated pair, a first supply terminal, and a shunt feedback stage, and configured to steer the first differential current between the first supply terminal and the shunt feedback stage.
2 more elements
A variable-gain amplifier comprising:
- a variable-gain voltage-to-current converter stage comprising:
- a grounded emitter-degenerated pair coupled to an input port and configured to convert an input signal at the input port to a first differential current;
- a transistor quad coupled to the grounded emitter degenerated pair, a first supply terminal, and a shunt feedback stage, and configured to steer the first differential current between the first supply terminal and the shunt feedback stage;
- and
- a current path coupled between the grounded emitter-degeneration pair and the first supply terminal, and configured to shunt a portion of the first differential current away from the transistor quad.
2 more elements
A variable-gain amplifier comprising:
- a variable-gain voltage-to-current converter stage comprising:
- a first input terminal;
- a second input terminal;
- a first resistor coupled to the first input terminal;
- a second resistor coupled to the second input terminal;
- a first transistor coupled between the first resistor and a first node;
- a second transistor coupled between the second resistor and a second node, wherein the first and the second transistors are coupled together in a common-base configuration;
- a third transistor coupled between the first node and a first output node;
- a fourth transistor coupled between the second node and a second output node;
- a fifth transistor coupled between the first node and a first supply terminal;
- and
- a sixth transistor coupled between the second node and a first supply terminal.
9 more elements
A variable-gain amplifier comprising:
- an input stage having an input and an output, wherein the input stage includes a grounded emitter-degenerated pair having first and second transistors coupled in a common-base configuration;
- a variable gain stage having an input, an output, a transistor quad, and a control voltage input, the input coupled to the output of the input stage;
- and
- a shunt feedback stage having an input and an output, the input coupled to the output of the transistor quad.
1 more element
A variable-gain amplifier comprising:
- an input stage having an input and an output, wherein the input stage is a grounded emitter-degenerated pair;
- a variable gain stage having an input, an output, a control voltage input, and a transistor quad, the input coupled to the output of the input stage;
- a shunt feedback stage having an input and an output, the input coupled to the output of the transistor quad, wherein the shunt feedback stage comprises:
- a first device coupled between a current source and a first output terminal;
- a second device coupled between the current source and a second output terminal;
- a first resistor coupled between a control terminal of the first device and the first output terminal;
- a second resistor coupled between a control terminal of the second device and the second output terminal;
- a third resistor coupled between the first output terminal and a first supply terminal;
- and
- a fourth resistor coupled between the second output terminal and the first supply terminal,
- wherein the first output terminal and the second output terminal form the output of the shunt feedback stage.
8 more elements
A variable-gain amplifier comprising:
- a variable gain stage comprising a first differential pair, a second differential pair, a first current path coupled in parallel with the first differential pair, and a second current path coupled in parallel with the second differential pair;
- a shunt feedback stage coupled to an output of the variable gain stage;
- and
- a differential emitter-follower buffer stage coupled to an output of the shunt feedback stage,
- wherein the differential emitter follower buffer stage comprises speed-up cross coupled capacitors.
2 more elements
A variable-gain amplifier comprising:
- a variable gain stage;
- a shunt feedback stage coupled to an output of the variable gain stage;
- and
- a differential emitter-follower buffer stage coupled to an output of the shunt feedback stage, wherein the differential emitter follower buffer stage comprises speed-up cross coupled capacitors that comprise a first capacitor coupled between the first resistor and the second current source and a second capacitor coupled between the second resistor and the first current source, a first device coupled between a first resistor and a first current source, and a second device coupled between a second resistor and a second current source;
- wherein the shunt feedback stage comprises:
- a third device coupled between a current source and a first output terminal;
- a fourth device coupled between the current source and a second output terminal;
- a third resistor coupled between a control terminal of the third device and the first output terminal;
- a fourth resistor coupled between a control terminal of the fourth device and the second output terminal;
- a fifth resistor coupled between the first output terminal and a first supply terminal;
- and
- a sixth resistor coupled between the second output terminal and the first supply terminal,
- wherein the first output terminal is coupled to a control electrode of the first device and the second output terminal is coupled to a control electrode of the second device.
10 more elements
Dependencies are inferred from the claim text.