电子信息与通信工程专业英语lesson2-2[001].ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,电子信息与通信工程专业英语,*,2025/6/26 周四,可编辑,1,Chapter 2,Circuit System and Design,Outline,2.1 Circuit and System,2.2 Analog and Digital Circuits Design,2.3 Radio Receiver Circuit,2025/6/26 周四,可编辑,2,2.2 Analog and Digital Circuits Design,Outline,Analog circuits,Digit Circuits,2025/6/26 周四,可编辑,3,Terminology,bipolar,adj.,双极型,CMOS,abbr.,Complementary Metal Oxide Semiconductor,互补型金属氧化物半导体,semiconducting material,半导体材料,Integrated circuits,集成电路,transistor,n.,晶体管,DC,abbr.,Direct Current,直流,AC,abbr.,Alternate Current,交流,digital,adj.,数字的,计数的,binary,adj.,具有两个的,;,二进制的,;,二变量的,Boolean algebra,布尔代数,positive,adj.,确实的,;,积极的,;,肯定的,;,现实的,;,正的,;,阳性的,2025/6/26 周四,可编辑,4,negative,adj.,否定的,否认的,;,反面的,消极的反对的,;,负的,;,阴极的,hexadecimal,adj.,十六进制的,number system,计数制,Commutative Law,交换律,Associative Law,结合律,Distributive Law,分配率,inverter,n.,变换器,;,倒相器,倒换器,;,反演器,;,逆变器,;“,非”门,truth table,n.,真值表,combinational,adj.,组合的,sequential,adj.,时序的,Flip-flop,n.,触发器,2025/6/26 周四,可编辑,5,Analog circuits are circuits dealing with signals free to vary from zero to full power supply voltage.,Analog circuits are often referred to as linear circuits to emphasize the valid continuity of signal range forbidden in digital circuits,but this label is unfortunately misleading.,Introduction,Text tour,1.Analog circuits,Modern circuit design is a mixed signal endeavor,thanks to,the availability of sophisticated process technologies that make available,bipolar,and,CMOS,power and signal,passive and active components on the same circuit.,2025/6/26 周四,可编辑,6,Just because a voltage or current signal is allowed to vary smoothly between the extremes of zero and full power supply limits does not necessarily mean that all mathematical relationships between these signals are linear in the straight-line or proportional sense of the word.Many so-called linear circuits are quite nonlinear in their behavior,either by necessity of physics or by design.,This relative mobility of electrons within a material is known as electric conductivity.Conductivity is determined by the types of atoms in a material(the number of protons in each atoms nucleus,determining its chemical identity)and how the atoms are linked together with one another.,2025/6/26 周四,可编辑,7,NPN transistors,In fact,in the most basic and most cost effective analog IC processes,the chip designer has at its disposal just that a good NPN transistor.,2025/6/26 周四,可编辑,8,In this component the current flow enters the collector and base and exits the emitter.Simply stated,the transistor conducts a collector current which is a copy of the base current amplified by a factor of beta.It follows that the emitter current is one plus beta times the base current.A typical value for the amplification factor is 100.,2025/6/26 周四,可编辑,9,The PNP transistor is complementary to the NPN,with the current flow entering the emitter and exiting the collector and base,the opposite of what happens in the NPN.,Simplicity dictates that PNPs are a by-product of the NPN construction,hence they often have less beta current gain and are slower than NPNs.,PNP transistors,2025/6/26 周四,可编辑,10,MOS transistors,The dual of,Bipolar,NPN and PNP transistors in CMOS technology are the P-Channel and N-Channel MOS transistors.The general function of the transistors is the same independently as their implementation but there are pros and cons to using both technologies.Generally speaking,the base,the emitter,and the collector of the bipolar transistor are analogous to the gate,source and drain of the MOS transistor,respectively.,2025/6/26 周四,可编辑,11,The,bipolar transistors,main problem,which is not present in CMOS,is their need for a base current in order to function.Such current is a net transfer loss from emitter to collector.While the base current is small in small signal operation,in power applications,where the transistor is used as a switch,the base current necessary to keep the transistor on can be very high.,2025/6/26 周四,可编辑,12,This high,base current,can lead to implementations with very poor efficiency.With the popularity of portable electronics and the need to extend battery life,it is no wonder that CMOS often tends to have the upper hand over bipolar technologies.The advantage of bipolar over CMOS that it has better trans-conductance gain and better matching,leading to better differential input gain stages and better voltage references.The best performance processes are mixed-mode BiCMOS(Bipolar and CMOS)or BCD(Bipolar CMOS and DMOS)processes in which the designer can use the best component for the task at hand.,2025/6/26 周四,可编辑,13,2.Digit Circuits,Boolean algebra fundamentals,The phrase“Digital electronics”is used to describe those circuit systems which primarily operate with the use of only two different voltage levels or two other binary states.Analog devices and systems process time-varying signals that can take on any value across a continuous range of voltage,current or other metric.,The difference is that we can pretend that they dont.,2025/6/26 周四,可编辑,14,The,NOT operation,changes the value to the complement of the value.This is also referred to as inversion or negation.,The,AND operation,is a Boolean multiply and is 1 only when all values are 1.The AND is like the old string of Christmas lights.All the lights have to work to have the stringy light.,The,OR operation,results in a 1 if any of the values are 1.In Boolean algebra,1+1=1 is valid.Logically the statement means if there are one or more true values,the result is true.,2025/6/26 周四,可编辑,15,Commutative Law:A+B=B+A,Associative Law of Addition:A+B+C=A+(B+C),Associative Law of multiplication:A(BC)=(AB)C,Distributive Law:A(B+C)=AB+AC,Identity:1A=A,0+A=A,Complement:A+A=1.AA=0,De Morgans Theorem:,2025/6/26 周四,可编辑,16,Logic gates,In general,a gate has one or more inputs and produces an output that is a function of the current input value(s).With each logic element there is a“truth table”that explains how the unit works.And there is a symbol to represent every gate.,The basic electronic digital operations are also NOT,AND,OR,but there are combinations of these that are also commonly used:the NAND,NOR,and EXCLUSIVE NOR.,2025/6/26 周四,可编辑,17,Combinational logic and sequential logic circuit,Logic circuits are classified into two types:combinational and sequential.A combinational logic is one whose outputs depend only on its current input.A combinational logic circuit may contain an arbitrary number of logic gates and inverters but no feedback loops(a signal path of a circuit that allows the output of a gate to propagate back to the input of that same gate).,2025/6/26 周四,可编辑,18,When the input is combined with the previous state of the logic circuits,it is referred to as sequential logic.The use of the previous state is called feedback.The outputs of sequential logic circuit depend not only on the current inputs but also on the past sequence of inputs,possibly arbitrarily far back in time.A seal-in circuit is an example of a sequential logic circuit.,2025/6/26 周四,可编辑,19,In the analysis,use logic diagram and proceed to a formal description of the function performed by that circuit,such as a truth table or a logic expression.In the synthesis,from a formal description and proceeding to a logic diagram.We have learned that there are five possible representations for a combinational logic function:,1.truth table,2.an algebraic sum of minterms,the canonical sum,3.a minterm list using the notation,4.an algebraic product of maxterms,the canonical product,5 a maxterm list using the notation,2025/6/26 周四,可编辑,20,Karnaugh map,like Boolean algebra,is a simplification tool applicable to digital logic.Boolean simplification is actually faster than the Karnaugh map for a task involving two or fewer Boolean variables.It is still quite usable at three variables,but a bit slower.At four input variables,Boolean algebra becomes tedious.Karnaugh maps are both faster and easier.Karnaugh maps work well for up to six input variables,are usable for up to eight variables.For more than six to eight variables,simplification should be by CAD(computer automated design).It simplifies a logic function by combining pairs of adjacent 1 cells into a Sum-Of-Products terms that covers all of the 1 cells.Form groups of 1s to cover all 0s.The Product-Of-Sums simplified result is built.By the definition of minimal cost solution,the SOP solution is simpler.,2025/6/26 周四,可编辑,21,Flip-flop is the common name given to two-state devices which offer basic memory for,sequential logic,operations.Flip-flops are heavily used for digital data storage and transfer and are commonly used in banks called registers for the storage of binary numerical data.,Flip-Flops,2025/6/26 周四,可编辑,22,2025/6/26 周四,可编辑,23,In an S-R latch,activation of the S input sets the circuit,while activation of the R input resets the circuit.If both S and R inputs are activated simultaneously,the circuit will be in an invalid condition.,The J-K flip-flop is a modified version of an S-R flip-flop with no“invalid”or“illegal”output state.So a J-K flip-flop is nothing more than an S-R flip-flop with an added layer of feedback.This feedback selectively enables one of the two set/reset inputs so that they cannot both carry active signal to the multivibrator circuit,thus eliminating the invalid condition.,2025/6/26 周四,可编辑,24,The D flip-flop tracks the input,making transitions with match those of the input D.The D stands for data;this flip-flop stores the value that is on the data line.It can be thought of as a basic memory cell.A D flip-flop can be made from a,set/reset flip-flop,by tying the set to the reset through an inverter.The result may be,clocked,.,The T or toggle,flip-flop,changes its output on each,clock edge,giving an output which is half the frequency of the signal to the T input.It is useful for constructing,binary counters,frequency dividers,and general,binary addition,devices.It can be made from a,J-K flip-flop,by tying both of its inputs high.,2025/6/26 周四,可编辑,25,EXERCISES,2025/6/26 周四,可编辑,26,The end of lesson 2.2,Thanks!,