Temperature compensated amplifier
AssigneeRaytheon Company
InventorsHieu M. Le, Lloyd F. Linder, Erick M. Hirata, Don C. Devendorf
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Abstract
An amplifier includes an amplifying circuit and bias current circuit. The bias current circuit includes a beta matching circuit which employs a temperature compensated current reference to develop a bias current for the amplifying circuit. The beta matching circuit is connected to track the current gains of transistors within the amplifying circuit and to thereby provide a temperature compensated bias current to the amplifying circuit. The bias current maintains a fixed bias point regardless of temperature-induced, or other, variations of the current gains of the amplifying circuit's transistors.
Claims12
A temperature compensated bias current source for providing bias current to an amplifier which includes a transistor circuit with at least one transistor have a current gain (.beta.) with a known temperature variation, comprising:
- a temperature compensated reference current source,
- a first current mirror connected to receive a reference current from said reference current source as an input,
- a beta matching circuit, comprising a respective transistor having the same current gain as each transistor within the amplifier, driven by said first current mirror to provide an output programming current characterized by said known temperature variation, and
- a second current mirror connected to be driven by said programming current to provide a bias current for said amplifier equal to N times the said programming current, wherein N is a predetermined fixed ratio.
A temperature compensated amplifier which includes a transistor circuit with at least one transistor having a current gain (.beta.) with a known temperature variation, comprising:
- an amplifying circuit including a transistor having current conduction terminals and a current control terminal, said transistor connected to amplify signals presented to its current control terminal, and
- a temperature compensation bias current source connected to provide bias current to said amplifying circuit, said bias current source comprising:
- a temperature compensated reference current source,
- a first current mirror connected to receive a reference current from said reference current source as an input,
- a beta matching circuit, comprising a transistor having the same current gain as a transistor within the amplifying circuit, driven by said first current mirror to provide an output programming current characterized by said known temperature variation, and
- a second current mirror connected to be driven by said programming current to provide a bias current for said amplifier equal to N times the said programming current, wherein N is a predetermined fixed ratio.
Dependencies are inferred from the claim text.