Digital Logical Circuit（俞鹤伟）chapter3-b.pptVIP

* 3.3.4 CMOS NAND NOR Gates * Switch model for NAND gate * NOR Gates * 3.3.5 Fan-In the number of inputs that a gate can have in a particular logic family * Three-state outputs Except the normal two states —— 0 and 1, there is another state —— Hi-Z, high-impedance state, which is controlled by an extra “output enable” control input. * 3.4 Electrical Behavior of CMOS Circuits It’s important to understand the electrical behavior when you design real circuits using CMOS or other logic families. Logic voltage levels: CMOS devices operating under normal conditions are guaranteed to produce output voltage levels within LOW and HIGH ranges. Power consumption Noise: caused by other electronic action , can disturb the working of CMOS devices. Fanout: refers to the number and type of inputs that are connected to a given output. * Transition Time The amount of time that the output of a logic circuit takes to change from one state to another. * Propagation Delay The amount of time that it takes for a change in the input signal to produce a change in the output in a signal path.