Current-steering CMOS logic family
First Claim
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1. A mixed mode integrated circuit comprising:
- a substrate;
one or more analog circuits fabricated on said substrate; and
one or more digital circuits fabricated on said substrate;
at least one of said digital circuits comprising;
a CMOS input transistor;
a CMOS output transistor;
first and second power lines;
a constant current source;
the sources of the input and output transistors being connected together and coupled to the second power line;
the gate of the input transistor being connected to a digital circuit input terminal;
the gate of the output transistor being connected to the drain of the input transistor;
the drain of the output transistor being connected to a digital circuit output terminal;
the drain of the output transistor being coupled to the first power line through the constant current source; and
the drain of the input transistor being connected to one of either the digital input terminal or the digital output terminal;
wherein switching currents from the digital circuits are prevented from generating large noise spikes.
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Abstract
In integrated circuitry having both analog and digital circuits fabricated on the same substrate, switching transients produced by the digital circuitry can propagate through the substrate and induce deleterious effects in the associated analog circuitry. Such switching transients are greatly minimized by the disclosed family of CMOS logic circuits in which a constant DC bias current is steered to change logic states.
49 Citations
22 Claims
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1. A mixed mode integrated circuit comprising:
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a substrate; one or more analog circuits fabricated on said substrate; and one or more digital circuits fabricated on said substrate; at least one of said digital circuits comprising; a CMOS input transistor; a CMOS output transistor; first and second power lines; a constant current source; the sources of the input and output transistors being connected together and coupled to the second power line; the gate of the input transistor being connected to a digital circuit input terminal; the gate of the output transistor being connected to the drain of the input transistor; the drain of the output transistor being connected to a digital circuit output terminal; the drain of the output transistor being coupled to the first power line through the constant current source; and the drain of the input transistor being connected to one of either the digital input terminal or the digital output terminal; wherein switching currents from the digital circuits are prevented from generating large noise spikes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A MOS logic circuit featuring reduced switching currents, the circuit comprising:
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a MOS input transistor; a MOS output transistor; first and second power lines; a constant current source; the sources of the input and output transistors being connected together and coupled to the second power line; the gates of the input and output transistors being connected together and connected to the drain of the input transistor, the drain of the input transistor defining an input terminal; and the drain of the output transistor being coupled to the first power line through the constant current source and defining an output terminal; wherein switching currents are prevented from generating large noise spikes. - View Dependent Claims (16, 17, 18, 19)
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20. A MOS logic circuit featuring reduced switching currents, the circuit comprising:
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a MOS input transistor; a MOS output transistor; first and second power lines; a constant current source; the sources of the input and output transistors being connected together and coupled to the second power line; the drains of the input and output transistors being connected together and to the gate of the output transistor and defining a voltage-mode output terminal, said connected drains being coupled to the first power line through the constant current source; the gate of the input transistor defining a voltage mode input terminal; wherein switching currents are prevented from generating large noise spikes. - View Dependent Claims (21, 22)
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Specification