Presentation on theme: "Chapter 10 Digital CMOS Logic Circuits"— Presentation transcript:
1 Chapter 10 Digital CMOS Logic Circuits 10.1 Digital circuit design : An overview10.2 Design and performance analysis of the CMOS inverter10.3 CMOS logic gate circuits10.4 Pseudo- NMOS logic circuits
2 10. 1 Digital circuit Design : An Overview 10. 1 10.1 Digital circuit Design : An Overview Digital IC technologies and logic circuit families Fig Digital IC technologies and logic circuit families
3 CMOS Replaced NMOS (much lower power dissipation) Small size, ease of fabricationChannel length has decreased significantly (as short as 0.06 µm or shorter)Low power dissipation than bipolar logic circuits ( can pack more) .High input impedance of MOS transistors can be used to storage charge temporarily (not in bipolar)High levels of integration for both logic (chapter 10) and memory circuits (chapter 11) .Dynamic logic to further reduce power dissipation and to increase speed performance .
4 BipolarTTL (Transistor-transistor logic) had been used for many years .ECL (Emitter –Coupled Logic) : basic element is the differential BJT pair in chapter 7 .BiCMOS : combines the high speed of BJT’s with low power dissipation of CMOS .GaAs : for very high speed due to the high carrier mobility . Has not demonstrated its potential commercially .
5 Features to be Considered Interface circuits for different familiesLogic flexibilitySpeedComplex functionsNoise immunityTemperaturePower dissipationCo$t
6 10. 1. 2 Logic circuit characterization Fig. 10 Logic circuit characterization Fig Typical voltage transfer (VTC) of a logic inverter .
15 Fan-In and Fan -Out Fan-in of a gate : number of inputs . Fan-out : maximum number of similar gates that a gate can drive while remaining within guaranteed specifications (to keep NMH above certain minimum) .
16 10. 2 Design and performance analysis of the CMOS inverter. 10. 2 10.2 Design and performance analysis of the CMOS inverter Circuit structure Fig (a) The CMOS inverter and (b) its representation as a pair of switches operated in a complementary fashion .