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US 2005/0024142 A1Published application
Variable gain amplifier system
AssigneeSkyworks Solutions, Inc.
InventorTirdad Sowlati
Life of this patent
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Abstract
A system for controlling gain in a polar loop is disclosed. Embodiments of the invention provide for a substantially constant gain tolerant of changes in supply voltage, ambient temperature, and/or manufacturing process.
Claims44
An amplifier system, comprising:
- a variable gain amplifier having:
- differential pair transistors;
- a degeneration element coupled to the differential pair transistors;
- and
- a collector load of a similar type to the degeneration element, wherein the collector load is coupled to the differential pair transistors, wherein a gain of the variable gain amplifier is determined by a physical dimension ratio of the collector load to the degeneration element for a differential input control voltage equal to zero volts.
2 more elements
An amplifier system, comprising:
- a variable gain amplifier having:
- a differential pair circuit having a first three terminal device and a second three terminal device;
- a first control terminal that receives a first control voltage derived from a differential input control voltage;
- degeneration resistive elements coupled between the differential pair circuit and the first control terminal;
- a second control terminal that receives a second control voltage derived from the differential input control voltage, the second control voltage opposite in polarity to the first control voltage;
- and
- collector load resistive elements coupled between the differential pair circuit and the second control terminal, the collector load resistive elements being substantially the same type as the degeneration resistive elements, wherein a gain of the system is determined by a physical dimension ratio of the collector load resistive elements to the degeneration resistive elements for the differential input control signal equal to zero volts.
4 more elements
A method of operating a variable gain amplifier, comprising:
- providing an input signal to a differential pair circuit;
- loading the differential pair circuit with degeneration resistive elements and collector load resistive elements;
- applying a first control voltage to the degeneration resistive elements;
- applying a second control voltage to the collector load resistive elements that is opposite in polarity to the first control voltage;
- and
- configuring the degeneration resistive elements to be substantially the same type as the collector load resistive elements, wherein a gain of the variable gain amplifier is determined by a physical dimension ratio of the collector load resistive elements to the degeneration resistive elements at a differential input control voltage equal to zero volts.
3 more elements
An amplifier system, comprising:
- a first variable gain amplifier having:
- a first differential pair circuit having a first three terminal device and a second three terminal device, the first and the second three terminal devices each having an emitter terminal, a collector terminal, and a base terminal;
- a first control terminal that receives a first control voltage;
- a variable emitter load coupled to the emitter terminals of the first differential pair circuit;
- a constant resistance load coupled to the collector terminals of the first differential pair circuit;
- and
- a second variable gain amplifier having:
- a second differential pair circuit having a first three terminal device and a second three terminal device, the first and the second three terminal devices each having an emitter terminal, a collector terminal, and a base terminal;
- a second control terminal that receives a second control voltage;
- a variable collector load coupled to the collector terminals of the first differential pair circuit;
- and
- a second constant resistance load coupled to the emitter terminals of the first differential pair circuit, wherein the variable emitter load is of substantially the same type as the variable collector load, wherein a gain of the variable gain amplifier system is dependent on a physical size ratio of the variable collector load to the variable emitter load at a differential input control voltage equal to zero volts.
9 more elements
A method of operating a variable gain amplifier system, comprising:
- providing a first input signal to a first differential pair circuit and a second differential pair circuit, the first differential pair circuit and the second differential pair circuit including emitter terminals, base terminals, and collector terminals;
- loading the emitter terminals of the first differential pair circuit with a variable emitter load;
- loading the collector terminals of the first differential pair circuit with a constant resistance load;
- controlling the variable emitter load with a first control voltage;
- loading the emitter terminals of the second differential pair circuit with a constant resistance load;
- loading the collector terminals of the second differential pair circuit with a variable collector load;
- and
- configuring the variable collector load to be substantially the same type as the variable emitter load, wherein a gain of the variable gain amplifier system is dependent on a physical size ratio of the variable collector load to the variable emitter load at a differential input control voltage equal to zero volts.
5 more elements
Dependencies are inferred from the claim text.