Variable gain amplifier
First Claim
1. A variable gain amplifier comprising first and second gain stages cascade connected between first and second terminals of a voltage supply generator, characterized in that the first gain stage comprises a differential stage coupled to the first terminal of the voltage supply generator and having first and second input terminals which form first and second input terminals for the amplifier, as well as first and second output terminals coupled to the second terminal of the voltage supply generator, respectively through first and second variable resistance load elements having a first common control terminal, and that the second gain stage comprises first and second transistors each having first and second terminals and a control terminal, the control terminals of said first and second transistors being respectively connected to the first and second output terminals of the differential stage, the first terminals of said first and second transistors being both coupled to the first terminal of the voltage supply generator and forming respectively a first output terminal and a second output terminal for the amplifier, the second terminals of the first and second transistors being both coupled to the second terminal of the voltage supply generator through respective first and second variable resistance circuit elements which are both connected to a second common control terminal.
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Accused Products
Abstract
A temperature-stable variable gain amplifier having a differential input stage coupled to a first terminal of a voltage supply generator and a second terminal of the voltage supply generator through first and second field-effect transistors whose gate terminals are connected to two bipolar transistors which are also connected between the first terminal of the voltage supply generator, through two resistors, and the second terminal of the voltage supply generator, through third and fourth field-effect transistors. Also, the third and fourth transistors have gate terminals connected into a second common control terminal, and the collector terminals of the bipolar transistors form output terminals for the amplifiers.
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Citations
15 Claims
- 1. A variable gain amplifier comprising first and second gain stages cascade connected between first and second terminals of a voltage supply generator, characterized in that the first gain stage comprises a differential stage coupled to the first terminal of the voltage supply generator and having first and second input terminals which form first and second input terminals for the amplifier, as well as first and second output terminals coupled to the second terminal of the voltage supply generator, respectively through first and second variable resistance load elements having a first common control terminal, and that the second gain stage comprises first and second transistors each having first and second terminals and a control terminal, the control terminals of said first and second transistors being respectively connected to the first and second output terminals of the differential stage, the first terminals of said first and second transistors being both coupled to the first terminal of the voltage supply generator and forming respectively a first output terminal and a second output terminal for the amplifier, the second terminals of the first and second transistors being both coupled to the second terminal of the voltage supply generator through respective first and second variable resistance circuit elements which are both connected to a second common control terminal.
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13. A variable gain amplifier having a first input terminal and a second input terminal as well as a first output terminal and a second output terminal, said variable gain amplifier comprising:
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a first gain stage comprising; a differential stage coupled to a voltage supply generator having a first terminal and a second terminal, said differential stage including; a first variable resistance load element having a first terminal coupled to the first input terminal of the amplifier and a second terminal coupled to the second terminal of the voltage supply generator, said first variable resistance load element coupled to the second input terminal of the amplifier and a second terminal coupled also having a control terminal; a second variable resistance load element having a first terminal to the second terminal of the voltage supply generator, said second variable resistance load element also having a control terminal which is coupled to the control terminal of said first variable resistance load element; a first output terminal connected to the first terminal of said first variable resistance load element; and a second output terminal connected to the first terminal of said second variable resistance load element; and a second gain stage cascade connected with said first gain stage between the first terminal and the second terminal of the voltage supply generator, said second stage comprising; a first transistor having a first terminal coupled to the first terminal of the voltage supply generator and forming a first-second stage output terminal, a second terminal, and a control terminal, the control terminal of said first transistor being coupled to the first output terminal of said differential stage; a second transistor having a first terminal coupled to the first terminal of the voltage supply generator and forming a second-second stage output terminal, a second terminal, and a control terminal, said control terminal of said second transistor being coupled to said second output terminal of said differential stage; a third variable resistance load element coupling said second terminal of said first transistor to the second terminal of the voltage supply generator, said third variable resistance load element having a control terminal; and a fourth variable resistance load element coupling said second terminal of said second transistor to the second terminal of the voltage supply generator, said fourth variable resistance load element having a control terminal coupled to said control terminal of said third variable resistance load element. - View Dependent Claims (14, 15)
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Specification