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US 4,069,431 AGranted
Amplifier circuit
AssigneeRCA Corporation
InventorNicholas Kucharewski
Life of this patent
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Abstract
A current mirror amplifier (CMA) with controlled current gain, the current gain being changed, for example, responsive to the output condition of a comparator in which the CMA is used in a differential signal combining circuit. In such a comparator application the switched gain of the CMA imparts hysteresis to the comparator characteristics.
Claims11
A current amplifier with controlled current gain comprising:
- input, output and common terminals;
- a plurality of transistors of a first conductivity type, each having first and second electrodes with a controlled conduction path therebetween and having a control electrode, the conduction of the controlled conduction path of each transistor being controlled responsive to the potential between its second and control electrodes;
- the first and second electrodes of the first of the plurality of transistors connected respectively to the input terminal and the common terminal;
- the first electrode of the second of the plurality of transistors connected to the output terminal;
- the first and second electrodes of the third of the plurality of transistors connected respectively to the second electrode of the second transistor and the common terminal;
- direct-coupled feedback means between the first electrode of the first transistor and its control electrode to adjust the potential at the control electrode of the first transistor and condition the first transistor to conduct current, as applied to said input terminal, through its controlled conduction path;
- means for applying a potential substantially equal to the potential at the control electrode of the first transistor to the control electrodes of the second and third transistors;
- a source of gain-controlling signal;
- a controlled impedance means connected between the common and output terminals;
- and
- means for applying the gain-controlling signal to the controlled impedance means to vary, in accordance with the applied signal, the current gain of the amplifier within a range between a predetermined minimum current gain as defined by a ratio of the conductances of the first, second and third of the plurality of transistors and a predetermined maximum current gain as defined by the ratio of the conductances of first and second of the plurality of transistors.
8 more elements
A current amplifier, the current gain of which may be varied in response to a control signal comprising in combination:
- input, output and common terminals;
- a source of control signal;
- a first insulated gate field effect transistor (IGFET) having first and second electrodes defining a conduction path therebetween and a control electrode, the first electrode of the conduction path of said first transistor coupled to said common terminal and said second electrode coupled to said control electrode and said input terminal;
- second and third IGFET's each having a control electrode and a conduction path, the control electrodes of said second and third IGFET's being connected to said input terminal and the conduction paths of said second and third IGFET's being serially connected between said output and said common terminals;
- and
- switching means having a conduction path and a control electrode, said switch control electrode being connected to said control signal source and said switch conduction path being connected in parallel connection with the conduction path of one of said second and third IGFET's.
3 more elements
Dependencies are inferred from the claim text.