Area-efficient low-power bipolar current-mode logic
AssigneeNational Semiconductor Corporation
InventorMichael E. Wright
Life of this patent
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Abstract
Current mode logic configuration circuits are shown for use with linear integrated circuit chips. The circuits employ plural collector lateral transistors to provide logic current source outputs in response to logic current inputs that are accepted by NPN transistor current mirrors acting as current sinks. Conventional logic functions are detailed and a toggle flip-flop configuration is shown being composed of the basic logic gates. Since the disclosed current mode voltage swings are small the circuit speed is relatively high at a given shunt capacitance. Die surface area is low with many transistors sharing common n-epitaxial tubs.
Claims9
A current mode logic circuit for use in conjunction with linear integrated circuits which employ silicon epitaxial monolithic PN junction isolated construction, operable from first and second power supply terminals, said circuit comprising:
- lateral PNP transistor means, connected to said first power supply terminal, to act as current source means that will provide said circuit output means;
- vertical NPN transistor means connected, into current mirror configurations, to said second power supply terminal to act as current sink means that will provide said circuit input means;
- means for coupling said PNP and said NPN transistor means together to perform a desired logic function;
- and
- means for applying controlled currents to said circuit to determine the current logic state levels.
Dependencies are inferred from the claim text.