數(shù)電數(shù)字邏輯4

1、Applications of Karnaugh map Treatment of Dont care term Applications in logic operationMinimization of multi-outputJudge and eliminate static hazard“Dont-care” input combinationsThe output is not relied on these input combinations or they are never allowed!These input combinations is called d-set.U

2、se d-set for logic minimization( Minimal cost design )Note: need not cover all d-terms !Logic operations of Karnaugh maps Two Karnaugh map with same variables can do logic operations with their cells. Logic operations of Karnaugh maps More examplesLogic operation for dont-care cells If variables are

3、 more than 4 ? If variables are more than 4 ? If variables are more than 4 ? Multiple-output minimization Find the shared term by AND operation;Use the shared term for minimization !A glitch happened at a steady-state output because of circuit delays.Always happened in two-level circuits !Static-1 h

4、azard static-0 hazardStatic hazardHappened in AND-OR circuitsTwo inputs of OR-gate is complement and may be changed at the same time !Static-1 hazardHappened in OR-AND circuitsTwo inputs of AND-gate is complement and may be changed at same time !Static-0 hazardFind static hazard using karnaugh mapsF

5、ind neighboring cells between 1-sets in map! Eliminate the static hazard using mapsAdd new term to cover the neighboring cells! Dynamic hazardHappened in the circuits which have more than two levels !Different signal pass may have different time delay !When input changed once, output may be changed several time