Differential amplifier and filter circuit using the same
First Claim
1. A differential amplifier comprising:
- a first current source one end of which is connected to a power supply or a ground;
a first MOS transistor of a first conductivity type whose drain is connected to the other end of said first current source and whose gate is connected to a first input terminal;
a second MOS transistor of the first conductivity type whose source is connected to a source of said first MOS transistor and whose gate is connected to a second input terminal;
a third MOS transistor of the first conductivity type whose drain is connected to the sources of said first and second MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said first current source;
a second current source one end of which is connected to the power supply or the ground;
a fourth MOS transistor of the first conductivity type whose drain is connected to the other end of said second current source and whose gate is connected to said first input terminal;
a fifth MOS transistor of the first conductivity type whose source is connected to a source of said fourth MOS transistor and whose gate is connected to a third input terminal; and
a sixth MOS transistor of the first conductivity type whose drain is connected to the sources of said fourth and fifth MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said second current source, wherein a differential signal is inputted to said second and third input terminals, a voltage substantially equal to the DC voltage of said differential signal is inputted to said first input terminal, and a differential output is obtained from drains of said second and fifth MOS transistor.
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Abstract
A differential amplifier is constructed in such a manner that a unit includes the sources of a first and a second MOS transistor and the drain of a third MOS transistor are connected to each other, these MOS transistors being of the same conductivity type, the other end of a current source whose one end is connected to a power supply or the ground is connected to the drain of the first MOS transistor and the gate of the third MOS transistor, and the source of the third MOS transistor is connected to the power supply or the ground. Two units of the differential amplifier are connected in parallel. The differential amplifier supplies a differential input signal to gates of the first and second units and obtains the output from drains of the first and second units. Two units of the differential amplifier are connected in parallel, with the input terminals cross-coupled with each other, thereby constructing a differential amplifier of the completely differential type.
30 Citations
10 Claims
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1. A differential amplifier comprising:
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a first current source one end of which is connected to a power supply or a ground;
a first MOS transistor of a first conductivity type whose drain is connected to the other end of said first current source and whose gate is connected to a first input terminal;
a second MOS transistor of the first conductivity type whose source is connected to a source of said first MOS transistor and whose gate is connected to a second input terminal;
a third MOS transistor of the first conductivity type whose drain is connected to the sources of said first and second MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said first current source;
a second current source one end of which is connected to the power supply or the ground;
a fourth MOS transistor of the first conductivity type whose drain is connected to the other end of said second current source and whose gate is connected to said first input terminal;
a fifth MOS transistor of the first conductivity type whose source is connected to a source of said fourth MOS transistor and whose gate is connected to a third input terminal; and
a sixth MOS transistor of the first conductivity type whose drain is connected to the sources of said fourth and fifth MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said second current source, wherein a differential signal is inputted to said second and third input terminals, a voltage substantially equal to the DC voltage of said differential signal is inputted to said first input terminal, and a differential output is obtained from drains of said second and fifth MOS transistor. - View Dependent Claims (2, 3, 5)
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4. A differential amplifier comprising:
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a first current source one end of which is connected to a power supply or a ground;
a first MOS transistor of a first conductivity type whose drain is connected to the other end of said first current source and whose gate is connected to a first input terminal;
a second MOS transistor of the first conductivity type whose source is connected to a source of said first MOS transistor and whose gate is connected to a second input terminal;
a third MOS transistor of the first conductivity type whose drain is connected to the sources of said first and second MOS transistors, whose source is connected to the around or the power supply, and whose gate is coupled to the other end of said first current source;
a second current source one end of which is connected to the power supply or the ground;
a fourth MOS transistor of the first conductivity type whose drain is connected to the other end of said second current source and whose gate is connected to said first input terminal;
a fifth MOS transistor of the first conductivity type whose source is connected to a source of said fourth MOS transistor and whose gate is connected to a third input terminal;
a sixth MOS transistor of the first conductivity type whose drain is connected to the sources of said fourth and fifth MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said second current source; and
a current mirror circuit where one of the drains of said second and fifth MOS transistors serves as an input node and the other of the drains serves as an output node, wherein the output is obtained from the output node of said current mirror circuit.
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6. A differential amplifier comprising:
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a first current source one end of which is connected to a power supply or a ground;
a first MOS transistor of a first conductivity type whose drain is connected to the other end of said first current source and whose gate is connected to a first input terminal;
a second MOS transistor of the first conductivity type whose source is connected to a source of said first MOS transistor and whose gate is connected to second input terminal;
a third MOS transistor of the first conductivity type whose dram is connected to the sources of said first and second MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said first current source;
a second current source one end of which is connected to the power supply or the ground;
a fourth MOS transistor of the first conductivity type whose drain is connected to the other end of said second currently source and whose gate is connected to a third input terminal;
a fifth MOS transistor of the first conductivity type whose source is connected to a source of said fourth MOS transistor and whose gate is connected to said second input terminal; and
a sixth MOS transistor of the first conductivity type whose drain is connected to the sources of said fourth and fifth MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said second current source, wherein a differential signal is inputted to said first and third input terminals, a voltage substantially equal to the DC voltage of said differential signal is inputted to said second input terminal, and a differential output is obtained from drains of said second and fifth MOS transistors. - View Dependent Claims (7, 8, 10)
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9. A differential amplifier comprising:
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a first current source one end of which is connected to a power supply or a ground;
a first MOS transistor of a first conductivity type whose drain is connected to the other end of said first current source and whose sate is connected to a first input terminal;
a second MOS transistor of the first conductivity type whose source is connected to a source of said first MOS transistor and whose gate is connected to second input terminal;
a third MOS transistor of the first conductivity type whose drain is connected to the sources of said first and second MOS transistors, whose source is connected to the ground or the power supply, and whose gate is coupled to the other end of said first current source;
a second current source one end of which is connected to the power supply or the ground;
a fourth MOS transistor of the first conductivity type whose drain is connected to the other end of said second currently source and whose gate is connected to a third input terminal;
a fifth MOS transistor of the first conductivity type whose source is connected to a source of said fourth MOS transistor and whose sate is connected to said second input terminal;
a sixth MOS transistor of the first conductivity type whose drain is connected to the sources of said fourth and fifth MOS transistors, whose source is connected to the around or the power supply, and whose sate is coupled to the other end of said second current source; and
a current mirror circuit where one of the drains of said second and fifth MOS transistors serves as an input node and the other of the drains serves as an output node, wherein the output is obtained from the output node of said current mirror circuit.
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Specification