Back to results
US 5,049,834 AGranted
Amplifier having a constant-current bias circuit
OwnerTakafumi Kasaiinventor
Life of this patent
Estimating the term…
Abstract
An amplifier having an input stage with inverting and non-inverting input terminals, a voltage amplifier stage with relay terminals and being operatively connected to the input stage, a SEPP output stage with transistors and an output terminal, and a constant-current bias circuit between the relay terminals for absorbing current bypassing between the relay terminals. The transistors are connected to the output terminal via resistors. The constant-current bias circuit is free of being in direct connection with the output terminal. The amplifier is incorporated in place of an emitter follower in a compact disc player or laser video player and may be incorporated into a driver of a loudspeaker, a magneto-optical recording system or a magnetic disc system for mass storage.
Claims25
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 terminals;
- a SEPP output stage including an NPN transistor having a base connected to said first relay terminal and an emitter connected to one end of a first resistor, an output terminal 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 terminal and an emitter connected to another end of said second resistor;
- a second PNP transistor having an emitter connected to said first relay terminal, a collector connected to said second relay terminal and a base connected to said another end of the second resistor via a resistor;
- and
- a capacitor connected between the base and the emitter of said second PNP transistor, said second PNP transistor being free of direct connection with said output terminal.
3 more elements
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 terminals;
- a SEPP output stage including a first transistor having a gate connected to said first relay terminal and a source connected to one end of a first resistor, an output terminal connected to another end of said first resistor and to one end of a second resistor, and a second transistor having a gate connected to said second relay terminal and a source 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 terminals and controlling a value of the constant current flowing through said first and second relay 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 another 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.
2 more elements
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 terminals;
- a SEPP output stage including a first transistor having a base connected to said first relay terminal and an emitter connected to one end of a first resistor, an output terminal 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 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 terminals and controlling a value of the constant current flowing through said first and second relay 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 another end of the second resistor via a high-cut filter, said voltage-controlled constant current bias circuit comprising a junction type field effect transistor having a drain connected to one of said first and second relay terminals.
2 more elements
Am 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 terminals;
- a SEPP output stage having first and second transistors operatively connected to said first and second relay terminals respectively, first and second resistors operatively connected to said first and second transistors respectively, and an output terminal connected to said first and second resistors;
- a voltage-controlled constant current bias circuit connected between said first and second relay terminals for controlling a bias current flowing in said first and second resistors via a high-cut filter, said voltage-controllable constant current bias circuit being free of direct connection with said output terminal;
- said high-cut filter including a capacitor;
- and
- means for adversely charging said capacitor, interposed between a common of said high-cut filter and one of said first and second resistors, so as to avoid generating a rush current in said first and second transistors.
4 more elements
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 terminals;
- a SEPP output stage having an output terminal and means for providing source and sink current to said output terminal;
- positive and negative supply terminals in electrical connection with said SEPP output stage;
- a constant voltage bias circuit connected between said first and second relay terminals for maintaining a voltage constant within said SEPP output stage;
- and
- a constant current element connected between the output terminal and at least one of said voltage supply terminals for preventing switching between said source and sink current of said SEPP output stage from arising.
4 more elements
Dependencies are inferred from the claim text.