Transducer circuit with adjustable output impedance
First Claim
1. A transducer circuit comprising:
- a first transistor having base, collector and emitter electrodes and having its base electrode connected to an input terminal;
a second transistor, of type complementary to said first transistor, having base, collector and emitter electrodes and having its base connected to the emitter electrode of said first transistor and its emitter electrode connected to an output terminal through a first non-linear voltage dependent resistor;
a current source for controlling current flow through the emitter-collector paths of said first and second transistors; and
a second non-linear voltage dependent resistor connected between the emitter electrode of said first transistor and the base electrode of said second transistor, and wherein the current-voltage characteristics of the first and second non-linear voltage dependent resistors are equal.
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Accused Products
Abstract
An impedance converter includes an emitter follower constructed of a first transistor with a first resistor connected between an emitter electrode of the first transistor and an output terminal. Input to the emitter follower is provided by a second transistor of complementary type, with input signal applied to the base of the second transistor and the emitter electrode of the second transistor coupled to the base of the first transistor with a second resistor. Bias current in the second transistor and second resistor is in constant proportion to bias current in the first transistor and first resistor. Output impedance can be made positive, negative or zero by appropriate proportioning of the first and second resistors.
42 Citations
14 Claims
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1. A transducer circuit comprising:
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a first transistor having base, collector and emitter electrodes and having its base electrode connected to an input terminal; a second transistor, of type complementary to said first transistor, having base, collector and emitter electrodes and having its base connected to the emitter electrode of said first transistor and its emitter electrode connected to an output terminal through a first non-linear voltage dependent resistor; a current source for controlling current flow through the emitter-collector paths of said first and second transistors; and a second non-linear voltage dependent resistor connected between the emitter electrode of said first transistor and the base electrode of said second transistor, and wherein the current-voltage characteristics of the first and second non-linear voltage dependent resistors are equal.
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2. A transducer circuit comprising:
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an input terminal and an output terminal; first and second transistors of complementary conductivity types, having respective base, collector and emitter electrodes, with the base electrode of said first transistor coupled to said input terminal; first and second resistors, said first resistor being coupled between the emitter electrode of said first transistor and the base electrode of said second transistor, and said second resistor being coupled between the emitter electrode of the second transistor and said output terminal; a current source, coupled to the collector electrode of the second transistor, to provide current in a series circuit path including the emitter electrode of the first transistor and the first resistor, in a substantially fixed proportion to current conducted in the emitter electrode of said second transistor. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A transducer circuit comprising:
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an input terminal and an output terminal; first and second transistors of complementary conductivity types, having respective control, first and second electrodes, with the control electrode of said first transistor coupled to said input terminal, and wherein current conducted between the first and second electrodes of a respective transistor is controlled by potential applied between its control and first electrodes; first and second resistors, said first resistor being coupled between the first electrode of said first transistor and the control electrode of said second transistor, and said second resistor being coupled between the first electrode of the second transistor and said output terminal; a current source including, third and fourth transistors of like conductivity type, having respective control, first and second electrodes, having their respective control electrodes interconnected and coupled to the second electrode of said second transistor, their respective first electrodes coupled to a source of operating potential, and their respective second electrodes coupled to the second and control electrodes of the second transistor respectively, whereby current provided by said third transistor flows through a serial connection of said second resistor and the first electrode of the second transistor, and current provided by the fourth transistor flows through a serial connection of said first resistor and the first electrode of the first transistor.
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Specification