Back to results
US 4,290,025 AGranted
Amplifier arrangement with variable gain factor
AssigneeU.S. Philips Corporation
InventorRudy J. van de Plassche
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeU.S. Philips Corporation
InventorRudy J. van de Plassche
Estimating the term…
An amplifier arrangement with a variable gain factor comprising a first and a second emitter-coupled transistor and a third and a fourth emitter-coupled transistor. The collector electrodes of the first and third transistor are coupled to an output of the amplifier arrangement. Between the interconnected base electrodes of the first and the fourth transistor and the interconnected base electrodes of the second and the third transistor a control signal can be applied. A signal current is applied to the interconnected emitter electrodes of the first and the second transistor and to the interconnected emitter electrodes of the third and the fourth transistor by means of a first and a second voltage-current converter, respectively, at least one of the two converters comprising a signal input and both converters having negative feedback to the output of the amplifier arrangement.
An amplifier arrangement with variable gain comprising, a first and a second transistor with interconnected emitters, a third and a fourth transistor with interconnected emitters, an output coupled to the collectors of the first and the third transistor, means for applying a control voltage between the base electrodes of the first and the second transistor, means connecting the base electrode of the third transistor to the base electrode of the second transistor and the base electrode of the fourth transistor to the base electrode of the first transistor, quiescent current means for applying quiescent currents to the interconnected emitters of the first and the second transistor and to the interconnected emitters of the third and the fourth transistor, and signal current means for applying signal current to at least the interconnected emitters of the first and the second transistor, and wherein said signal current means comprise, a first voltage-current converter having a first input which is inverting relative to the output of the amplifier arrangement and a second input which comprises a first signal voltage input of the amplifier arrangement, a second voltage-current converter having at least a first input which is inverting relative to the output of the amplifier arrangement, and means connecting the first inputs of the first and the second voltage-current converters to the output of the amplifier arrangement.
A variable gain amplifier comprising, first, second, third and fourth transistors each having first and second electrodes defining a current path in the transistor and a control electrode, means interconnecting the first electrodes of the first and second transistors, means interconnecting the first electrodes of the third and fourth transistors, means interconnecting the control electrodes of the first and fourth transistors and the control electrodes of the second and third transistors to form first and second input terminals, respectively, for receiving a variable control voltage, an output terminal of the amplifier coupled to the interconnected second electrodes of the first and third transistors, means for applying quiescent currents to the interconnected first electrodes of the first and second transistors and to the interconnected first electrodes of the third and fourth transistors, and means for applying a signal current to the interconnected first electrodes of the first and second transistors comprising first and second voltage-current converters each having a first input coupled to the output terminal to provide a negative feedback and one converter having a separate signal voltage input terminal that is indepedent of said output terminal.
Dependencies are inferred from the claim text.