Transistor amplifier circuit
AssigneeHitachi, Ltd.
InventorsYoshio Sakamoto, Yasuo Kominami
Life of this patent
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Abstract
In a transistor amplifier circuit comprising a common-emitter amplifier transistor, a collector load resistance has one end connected with the collector of the transistor, a constant-current circuit is connected with the collector of the transistor, and an output of the transistor amplifier circuit is derived from the collector. The constant-current circuit supplies a constant current which is substantially equal to the d.c. emitter current flowing through the transistor and a d.c. voltage which establishes a d.c. voltage level of the output is applied to the other end of the collector load resistance, whereby no d.c. current is permitted to flow through the resistance.
Claims16
In a transistor amplifier circuit having
- an input terminal to which signals to be amplified are applied;
- an output terminal;
- a common-emitter transistor having its base electrode connected to said input terminal and its collector electrode connected to said output terminal;
- a power supply terminal to which a power supply voltage is applied;
- and
- a constant-current circuit connected between said power supply terminal and the collector of said common-emitter transistor;
- the improvement comprising:
- means for setting a D.C. voltage level at the collector of said common-emitter transistor including a D.C. voltage terminal to which a prescribed D.C. voltage exclusive of said power supply voltage is applied, and
- a load resistor connected between said D.C. voltage terminal and the collector of said common-emitter transistor, and
- wherein the value of current supplied by said constant-current circuit to the collector of said common-emitter transistor is equal to that of the D.C. emitter current of said common-emitter transistor.
A differential amplifier circuit comprising:
- an input terminal to which a voltage input is applied;
- an output terminal;
- a power supply terminal to which a power supply voltage is applied;
- first and second transistors, the emitters of which are coupled together, the base of said first transistor being connected to said input terminal, and the collector of said second transistor being connected to said output terminal;
- a constant-current circuit connected between said power supply terminal and the collectors of said transistors;
- means for setting a D.C. voltage level at the collector of said second transistor including a D.C. voltage terminal to which a prescribed D.C. voltage exclusive of said power supply voltage is applied;
- and
- a load resistor connected between said D.C. voltage terminal and the collector of said second transistor.
Dependencies are inferred from the claim text.