1Addendum:Digital Integrated CircuitsECE 152A – Fall 2006October 17, 2006ECE 152A - Digital Design Principles2Properties of Digital Integrated Circuits The Ideal Digital Circuit2October 17, 2006ECE 152A - Digital Design Principles3Digital IC Definitions Amplitude and Voltage Transfer CharacteristicsOctober 17, 2006ECE 152A - Digital Design Principles4Digital IC Definitions Noise Margins Sources of noise Definition of noise margins3October 17, 2006ECE 152A - Digital Design Principles5TTL Electrical Characteristics Standard TTL (54/74)October 17, 2006ECE 152A - Digital Design Principles6TTL Electrical Characteristics Comparison of Standard TTL (74), SchottkyClamped TTL (74S) and Low Power SchottkyTTL (74LS)4October 17, 2006ECE 152A - Digital Design Principles7TTL vs. CMOS Comparison of Electrical CharacteristicsOctober 17, 2006ECE 152A - Digital Design Principles8VLSI Circuits Intel 8080Address Bus DriversBidirectional Data BusDriver/ReceiversGround PadRegister ArrayInstructionDecodeArithmetic Logic UnitTiming and Control5October 17, 2006ECE 152A - Digital Design Principles9VLSI Circuits Intel PentiumOctober 17, 2006ECE 152A - Digital Design Principles10Power Dissipation in CMOS Circuits There are two components that establish the amount of power dissipation in a CMOS circuit Static Power Dissipation Constant current Dynamic Power Dissipation Currents attributed to switching6October 17, 2006ECE 152A - Digital Design Principles11Power Dissipation in CMOS Circuits Static dissipation Reverse bias leakage current  Parasitic diode between diffusion regions and substrate Subthreshold leakage current in static CMOS circuits pMOS and/or nMOS devices not completely turned off Constant current in non static CMOS circuits Psuedo-nMOS, I/O, Analog circuits, etc.October 17, 2006ECE 152A - Digital Design Principles12Power Dissipation in CMOS Circuits Dynamic dissipation Switching transient current Occurs on transition from 1 to 0 (or 0 to 1) Results in short current pulse from VDDto VSS Referred to as “short-circuit dissipation” Dependent on rise and fall times Slow rise and fall times increase short circuit current Critical in I/O buffer design Dominant component of dynamic power with little or no capacitive loading7October 17, 2006ECE 152A - Digital Design Principles13Power Dissipation in CMOS Circuits Dynamic dissipation (cont) Charging and discharging of load capacitances As capacitive loading is increased, the charging and discharging currents begin to dominate the current drawn from the power suppliesOctober 17, 2006ECE 152A - Digital Design Principles14Power Dissipation in CMOS Circuits Dynamic dissipation (cont) Charging and discharging of load capacitances8October 17, 2006ECE 152A - Digital Design Principles15Power Dissipation in CMOS Circuits Dynamic short-circuit vs. capacitive