Constant-current circuit for logic circuit in integrated semiconductor
First Claim
1. A constant-current circuit, for an integrated semiconductor circuit for which are provided a first power source and a second power source lower than said first power source, comprising:
- a constant-current transistor, to a source of which said second power source is connected and to a gate of which a bias voltage is applied, for supplying a constant-current;
a first stage circuit, including a plurality of diode elements, which are provided between said first power source and said second power source, and a first MESFET transistor with connected gate and drain, which is inserted into said plurality of diode elements, for generating a first voltage at a drain of said first MESFET;
a second MESFET transistor, to a gate of which said first voltage is applied, for generating a second voltage lower by the equivalent of a threshold voltage thereof than said first voltage; and
a bias voltage generator, including a resistor and a third transistor with connected gate and drain, which are provided between a source of said second MESFET transistor and said second power source, for generating said bias voltage at said gate of said third MESFET transistor.
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Abstract
According to the present invention, a first voltage is generated at a drain of a first MESFET by a first stage circuit that includes a plurality of diode elements and the first MESFET with its gate and drain connected together provided between power sources. The first voltage is applied to a gate of a second MESFET that performs a source follower operation so that a constant second voltage, which is lower by the equivalent of a threshold voltage than the first voltage, is generated at the source. A third MESFET with a diode connection is provided between the second voltage source and a lower power source, and a bias voltage is generated at the drain terminal of the third MESFET. The bias voltage is supplied to the gate of a constant-current transistor, the source of which is connected to the lower power source. The current of the constant-current transistor is supplied to an SCFL circuit, the source of which is connected for common use.
18 Citations
5 Claims
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1. A constant-current circuit, for an integrated semiconductor circuit for which are provided a first power source and a second power source lower than said first power source, comprising:
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a constant-current transistor, to a source of which said second power source is connected and to a gate of which a bias voltage is applied, for supplying a constant-current; a first stage circuit, including a plurality of diode elements, which are provided between said first power source and said second power source, and a first MESFET transistor with connected gate and drain, which is inserted into said plurality of diode elements, for generating a first voltage at a drain of said first MESFET; a second MESFET transistor, to a gate of which said first voltage is applied, for generating a second voltage lower by the equivalent of a threshold voltage thereof than said first voltage; and a bias voltage generator, including a resistor and a third transistor with connected gate and drain, which are provided between a source of said second MESFET transistor and said second power source, for generating said bias voltage at said gate of said third MESFET transistor. - View Dependent Claims (2, 3, 4, 5)
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Specification
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- Resources
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Current AssigneeFujitsu Limited
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Original AssigneeFujitsu Limited
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InventorsKazuno, Masataka
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Primary Examiner(s)Wong, Peter S.
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Assistant Examiner(s)Vu, Bao Q.
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Application NumberUS08/989,772Time in Patent Office788 DaysField of Search323/312, 323/315, 323/313, 323/314, 323/316, 327/530, 327/538, 327/543US Class Current323/312CPC Class CodesG05F 3/245 producing a voltage or curr...G05F 3/247 producing a voltage or curr...
