Composite differential amplifier
AssigneeNEC Corporation
InventorKazunori Nishijima
Life of this patent
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Abstract
There is provided a composite differential amplifier with a lower voltage and a lower power consumption of the circuit thereof. An output of a differential amplifier is inputted into an emitter-follower and is delivered as a DC voltage from an emitter of each of transistors of the emitter-follower to a non-inverting input terminal or an operational amplifier. Then, an output of the operational amplifier is supplied to a variable current source. The variable current source at its current drain side is connected to a resistance side of the differential amplifier so that an external control voltage inputted to the non-inverting input side of the operational amplifier is equal to the DC output voltage of the differential amplifier.
Claims9
A composite differential amplifier comprising:
- a power supply for supplying a power to a circuit;
- a differential amplifier for amplifying a voltage signal inputted from an input signal source;
- an emitter-follower connected to an output side of said differential amplifier for converting said voltage signal outputted from said differential amplifier into a DC voltage and for amplifying said voltage outputted from said differential amplifier 120;
- an operational amplifier connected to an output side of said emitter-follower for amplifying said DC voltage outputted from said emitter-follower;
- and
- a variable current source connected to an output side of said operational amplifier and connected to said output side of said differential amplifier for controlling a voltage of said output side of said differential amplifier in response to an output of said operational amplifier.
Dependencies are inferred from the claim text.