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Current mode logic (CML), or source-coupled logic (SCL), is a digital design style used both for logic gates and for board-level digital signaling of digital data.. The basic principle of CML is that current from a constant current generator is steered between two alternate paths depending on whether a logic zero or logic one is being represented.
A logic circuit diagram for a 4-bit carry lookahead binary adder design using only the AND, OR, and XOR logic gates.. A logic gate is a device that performs a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output.
I2L NOR gate with two inputs, two outputs, and one voltage input for the current injector transistor. The I2L inverter gate is constructed with a PNP common base current source transistor and an NPN common emitter open collector inverter transistor (i.e. they are connected to the GND). On a wafer, these two transistors are merged.
XOR has the worst-case Karnaugh map—if implemented from simple gates, it requires more transistors than any other function. Back when transistors were more expensive, designers of the Z80 and many other chips were motivated to save a few transistors by implementing the XOR using pass-transistor logic rather than simple gates. [4]
The picture represents a typical ECL circuit diagram based on Motorola's MECL. In this schematic, transistor T5′ represents the output transistor of a previous ECL gate that provides a logic signal to input transistor T1 of an OR/NOR gate whose other input is at T2 and has outputs Y and Y.
Each logic gate is designed to perform a function of Boolean logic when acting on logic signals. A logic gate is generally created from one or more electrically controlled switches, usually transistors but thermionic valves have seen historic use. The output of a logic gate can, in turn, control or feed into more logic gates.
Accordingly, neither of the two transistors will conduct and the transmission gate turns off. When the control input is a logic one, the gate terminal of the n-channel MOSFETs is located at a positive supply voltage potential. By the inverter, the gate terminal of the p-channel MOSFETs is now at a negative supply voltage potential.
A CMOS transistor NAND element. V dd denotes positive voltage.. In CMOS logic, if both of the A and B inputs are high, then both the NMOS transistors (bottom half of the diagram) will conduct, neither of the PMOS transistors (top half) will conduct, and a conductive path will be established between the output and Vss (ground), bringing the output low.