Two-wire type amplifier
AssigneeHitachi, Ltd.
InventorTsutomu Okayama
Life of this patent
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Abstract
Two differential amplifiers are provided each having two input terminals. One of the input terminals of each differential amplifier receives an output signal derived from a measuring circuit, while the other terminals of the differential amplifiers are coupled to each other. Output signals of the respective differential amplifiers control correspondingly two series-connected current control circuits, respectively. With such a circuit arrangement, a current flowing through a receiving unit connected in series to the two current control circuit is controlled in response to the output signal from the measuring circuit.
Claims5
A two-wire type amplifier comprising:
- a measuring circuit, having two output signals, to measure quantities to be measured;
- first and second differential amplifiers, each having first and second input terminals;
- one of the output signals derived from said measuring circuit being coupled to the first input terminal of said first differential amplifier, with the other output signal being coupled to the first input terminal of said second differential amplifier;
- first and second current control means being connected in series and controlled by said first and second differential amplifiers, respectively and
- wherein said first and second current control means are connected in series via a common resistor and further comprising feedback means for feeding back the voltage across said common resistor to the respective second input terminals of said first and second differential amplifiers;
- receiving means including a receiving resistor and a power source connected in series with said series-connected first and second current control means;
- and
- said first and second current control means controlling said power source current.
Dependencies are inferred from the claim text.