Amplifier having a constant-current bias circuit
First Claim
1. An amplifier comprising:
- an input stage having an inverting input terminal and a non-inverting input terminal;
a voltage amplifier stage operatively connected to said input stage and having first and second relay output terminals;
a SEPP output stage including a first transistor having a base connected to said first relay output terminal and an emitter connected to one end of a first resistor, an output terminal directly connected to another end of said first resistor and to one end of a second resistor, and a second transistor having a base connected to said second relay output terminal and an emitter connected to another end of said second resistor, said second transistor having a polarity opposite to said first transistor; and
a voltage-controlled constant current bias circuit connected between said first and second relay output terminals and controlling a value of the constant current flowing through said first and second relay output terminals in response to a control voltage that is a mean value of a voltage between said one end of the first resistor and said other end of the second resistor via a high-cut filter, said voltage-controlled constant current bias circuit being free of direct connection with said output terminal.
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Abstract
In an amplifier comprising an input stage having an inverting input terminal and a non-inverting input terminal, a voltage amplifier stage operatively connected to said input stage, and a SEPP output stage including first and second control ends connected to first and second relay output terminals of said voltage amplifier stage respectively, it is characterized by comprising a constant-current bias (CCB) circuit connected between the first and second relay output terminals so as to absorb the current bypassing between said relay output terminals. The first CCB circuit is connected in parallel to a so called constant-voltage bias circuit whose internal resistance has been increased as compared with that in the conventional CVB circuit so that most portion of the bias current borne by the CVB circuit is shared by the present CCB circuit. The second CCB circuit is a negative feedback-type CCB circuit which is controllable by means of a control voltage which is derived from a mean voltage generated from emitter resistor of power transistors, i.e., from the mean value of a voltage generated between the first and second resistors.
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Citations
6 Claims
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1. An amplifier comprising:
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an input stage having an inverting input terminal and a non-inverting input terminal; a voltage amplifier stage operatively connected to said input stage and having first and second relay output terminals; a SEPP output stage including a first transistor having a base connected to said first relay output terminal and an emitter connected to one end of a first resistor, an output terminal directly connected to another end of said first resistor and to one end of a second resistor, and a second transistor having a base connected to said second relay output terminal and an emitter connected to another end of said second resistor, said second transistor having a polarity opposite to said first transistor; and a voltage-controlled constant current bias circuit connected between said first and second relay output terminals and controlling a value of the constant current flowing through said first and second relay output terminals in response to a control voltage that is a mean value of a voltage between said one end of the first resistor and said other end of the second resistor via a high-cut filter, said voltage-controlled constant current bias circuit being free of direct connection with said output terminal. - View Dependent Claims (2, 3, 4)
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5. An amplifier comprising:
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an input stage having an inverting input terminal and a non-inverting input terminal; a voltage amplifier stage operatively connected to said input stage and having first and second relay output terminals; a SEPP output stage including a NPN transistor having a base connected to said first relay output terminal and an emitter connected to one end of a first resistor, an output terminal directly connected to another end of said first resistor and to one end of a second resistor, and a PNP transistor having a base connected to said second relay output terminal and an emitter connected to another end of said second resistor; a second NPN transistor having a collector connected to said first relay output terminal, an emitter connected to said second relay output terminal and a base connected to said one end of the first resistor via a resistor, said second NPN transistor being free of direct connection with said output terminal; and a capacitor connected between the base and the emitter of said second NPN transistor.
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6. An amplifier comprising:
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an input stage having an inverting input terminal and a non-inverting input terminal; a voltage amplifier stage operatively connected to said input stage and having first and second relay output terminals; a SEPP output stage including a first transistor having a base connected to said first relay output terminal and an emitter connected to one end of a first resistor, an output terminal directly connected to another end of said first resistor and to one end of a second resistor, and a second transistor opposite in conductivity to said first transistor having a base connected to said second relay output terminal and an emitter connected to another end of said second resistor; a bipolar transistor connected to said first relay output terminal via a connection line and connected to said second relay output terminal and having a base connected to be responsive to a voltage developed in response to a current flowing through said first and second resistors, said bipolar transistor being free of direct connection with said output terminal; and a capacitor connected between the base of said bipolar transistor and said connection line.
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Specification