Active load for emitter coupled logic gate
First Claim
1. An improved logic gate having first and second voltage terminals, first and second input terminals, a first output terminal, a first current source, a first transistor having a base coupled to said first input terminal, an emitter coupled to said first voltage terminal by said first current source, and a collector coupled to said first output terminal, and a second transistor having a base coupled to said second input terminal, an emitter coupled to said first voltage terminal by said first current source, and having a collector, said improvement comprising:
- a first resistor;
a second resistor;
a third resistor;
a fourth resistor;
a third transistor having its base coupled to its collector by said first resistor, and its collector-emitter path coupled in series with said second resistor between said collector of said first transistor and said second voltage terminal; and
a fourth transistor having its base coupled to its collector by said third resistor, and its collector-emitter path coupled in series with said fourth resistor between said collector of said second transistor and said second voltage terminal.
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Accused Products
Abstract
An active load for a CML or ECL logic gate for substantially increasing the speed of the gate comprises a transistor having its base coupled to its collector by a first resistor, and its collector-emitter path coupled in series with a second resistor. This load provides an inductive impedance when the small signal emitter resistance is less than the sum of the resistance of the base and the first resistor, causing a peaking effect resulting in high switching speed.
77 Citations
11 Claims
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1. An improved logic gate having first and second voltage terminals, first and second input terminals, a first output terminal, a first current source, a first transistor having a base coupled to said first input terminal, an emitter coupled to said first voltage terminal by said first current source, and a collector coupled to said first output terminal, and a second transistor having a base coupled to said second input terminal, an emitter coupled to said first voltage terminal by said first current source, and having a collector, said improvement comprising:
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a first resistor; a second resistor; a third resistor; a fourth resistor; a third transistor having its base coupled to its collector by said first resistor, and its collector-emitter path coupled in series with said second resistor between said collector of said first transistor and said second voltage terminal; and a fourth transistor having its base coupled to its collector by said third resistor, and its collector-emitter path coupled in series with said fourth resistor between said collector of said second transistor and said second voltage terminal. - View Dependent Claims (2, 3, 11)
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4. A logic gate comprising:
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a first supply voltage terminal; a second supply voltage terminal; a first input terminal; a second input terminal; a first output terminal; a first current source; a first resistor; a second resistor; a third resistor; a fourth resistor; a first transistor having a base coupled to said first input terminal, an emitter coupled to said second supply voltage terminal by said first current source, and a collector to said first output terminal; a second transistor having a base coupled to said second input terminal, an emitter coupled to said second supply voltage terminal by said first current source, and a collector; a third transistor having its base coupled to its collector by said first resistor, and its collector-emitter current path coupled in series with said second resistor between said collector of said first transistor and said first supply voltage terminal; and a fourth transistor having its base coupled to its collector by said third resistor, and its collector-emitter current path coupled in series with said fourth resistor between said collector of said second transistor and said first supply voltage terminal. - View Dependent Claims (5, 6)
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7. An logic gate comprising:
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a first supply voltage terminal; a second supply voltage terminal; a first input terminal; a second input terminal; a first output terminal; a first current source; a first resistor; a second resistor; a first transistor having a base coupled to said first input terminal, an emitter coupled to said second supply voltage terminal by said first current source, and a collector; a second transistor having a base coupled to said second input terminal, an emitter coupled to said second supply voltage terminal by said first current source, and a collector; a third transistor having its base coupled to its collector by said first resistor, and its collector-emitter current path coupled in series with said second resistor between said collector of said first transistor and said second supply voltage terminal; and first means coupled between said collector of said first transistor and said first output terminal for amplifying the voltage on said collector of said first transistor. - View Dependent Claims (8, 9, 10)
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Specification