Lesson 20 Flip-Flop电子技术专业英语教程.pptx

Lesson 20 Flip-Flop电子技术专业英语教程冯新宇 主编电子工业出版社电子工业出版社 Unit7 Digital Logic Circuit2021/9/121电子技术专业英语教程Lesson 20 Flip-FlopBackgroundsText tour Language in useVocabulary Structure Reading/writing techniques2021/9/122电子技术专业英语教程Terminology multivibratorn.【计】多谐振荡器field effect transistor【计】场效应晶体管shift register移位寄存器Backgrounds2021/9/123电子技术专业英语教程Text tour Outline Flip-flop Flip-flops inventionSimple flip-flopsClocked flip-flopsThe type of flip-flopsSetreset flip-flops(SR flip-flops)Trigger flip-flops(T flip-flops)JK flip-flopD flip-flop2021/9/124电子技术专业英语教程Flip-flopIn digital circuits,a flip-flop is a term referring to an electronic circuit(a bistable multivibrator)that has two stable states and thereby is capable of serving as one bit of memory.Today,the term flip-flop has come to mostly denote non-transparent(clocked or edge-triggered)devices,while the simpler transparent ones are often referred to as latches;however,as this distinction is quite new,the two words are sometimes used interchangeably.A flip-flop is usually controlled by one or two control signals and/or a gate or clock signal.The output often includes the complement as well as the normal output.As flip-flops are implemented electronically,they require power and ground connections.2021/9/125电子技术专业英语教程Flip-flops inventionThe first electronic flip-flop was invented in 1918 by William Eccles and F.W.Jordan.It was initially called the Eccles-Jordan trigger circuit and consisted of two active elements.The name flip-flop was later derived from the sound produced on a speaker connected to one of the back coupled amplifiers outputs during the trigger process within the circuit.This original electronic flip-flopa simple two-input bistable circuit without any dedicated clock signal was transparent,and thus a device that would be labeled as a latch in many circles today.2021/9/126电子技术专业英语教程Simple flip-flopsSimple flip-flops can be built around a pair of cross-coupled inverting elements:vacuum tubes,bipolar transistors,field effect transistors,inverters,and inverting logic gates have all been used in practical circuits-perhaps augmented by some gating mechanism.The more advanced clocked devices are specially designed for synchronous systems;such devices therefore ignore its inputs except at the transition of a dedicated clock signal.This causes the flip-flop to either change or retain its output signal based upon the values of the input signals at the transition.Some flip-flops change output on the rising edge of the clock,others on the falling edge.2021/9/127电子技术专业英语教程Clocked flip-flopsClocked flip-flops are typically implemented as master-slave devices where two basic flip-flops(plus some additional logic)collaborate to make it insensitive to spikes and noise between the short clock transitions;they nevertheless also often include asynchronous clear or set inputs which may be used to change the current output independent of the clock.2021/9/128电子技术专业英语教程The type of flip-flops Flip-flops can be further divided into types that have found common applicability in both asynchronous and clocked sequential systems:the SR(set-reset),D(data or delay),T(trigger),and JK types are the common ones;all of which may be synthesized from other types by a few logic gates.The behavior of a particular type can be described by what is termed the characteristic equation,which derives the next(i.e.,after the next clock pulse)output,Qnext,in terms of the input signal(s)and/or the current output,Q.2021/9/129电子技术专业英语教程Setreset flip-flops(SR flip-flops)The fundamental latch is the simple SR flip-flop,where S and R stand for set and reset respectively.It can be constructed from a pair of cross-coupled NAND or NOR logic gates.The stored bit is present on the output marked Q.SR Flip-Flop operationCharacteristic tableExcitation tableSRActionQ(t)Q(t+1)SRAction00Keep state000 xNo change01Q=00110Set10Q=11001Reset11Unstable combination11x0No change2021/9/1210电子技术专业英语教程Setreset flip-flops(SR flip-flops)Normally,in storage mode,the S and R inputs are both low,and feedback maintains the Q and outputs in a constant state,with the complement of Q.If S is pulsed high while R is held low,then the Q output is forced high,and stays high even after S returns low;similarly,if R is pulsed high while S is held low,then the Q output is forced low,and stays low even after R returns low.Figure 20-1 shows the symbol for a SR latch.Figure 20-1 The symbol for a SR latch2021/9/1211电子技术专业英语教程Trigger flip-flops(T flip-flops)If the T input is high,the T flip-flop changes state(toggles)whenever the clock input is strobed.If the T input is low,the flip-flop holds the previous value.This behavior is described by the characteristic equation:(or,without benefit of the XOR operator,the equivalent:)and can be described in a truth table:T Flip-Flop operationCharacteristic tableExcitation tableTQQnextCommentQQnextTComment000hold state000No change011hold state110No change101toggle011Complement110toggle101Complement2021/9/1212电子技术专业英语教程Trigger flip-flops(T flip-flops)Figure 20-2 shows T-type flip-flop.When T is held high,the trigger flip-flop divides the clock frequency by two;that is,if clock frequency is 4 MHz,the output frequency obtained from the flip-flop will be 2 MHz.This divide by feature has application in various types of digital counters.A T flip-flop can also be built using a JK flip-flop(J&K pins are connected together and act as T)or D flip-flop(T input and Qprevious is connected to the D input through an XOR gate).Figure 20-2 T-type flip-flop 2021/9/1213电子技术专业英语教程JK flip-flopThe JK flip-flop augments the behavior of the SR flip-flop(J=Set,K=Reset)by interpreting the S=R=1 condition as a flip or toggle command.Specifically,the combination J=1,K=0 is a command to set the flip-flop;the combination J=0,K=1 is a command to reset the flip-flop;and the combination J=K=1 is a command to toggle the flip-flop,i.e.,change its output to the logical complement of its current value.Setting J=K=0 does NOT result in a D flip-flop,but rather,will hold the current state.To synthesize a D flip-flop,simply set K equal to the complement of J.The JK flip-flop is therefore a universal flip-flop,because it can be configured to work as an SR flip-flop,a D flip-flop,or a T flip-flop.NOTE:The flip flop is positive edge triggered(Clock Pulse)as seen in Figure 20-3.Figure 20-3 JK flip-flop2021/9/1214电子技术专业英语教程JK flip-flopThe characteristic equation of the JK flip-flop is:and the corresponding truth table is:JK Flip-Flop operationCharacteristic tableExcitation tableJKQnextCommentQQnextJKComment00Qprevhold state000 xNo change010reset111xset101set10 x1reset11toggle11x0No change2021/9/1215电子技术专业英语教程D flip-flopThe Q output always takes on the state of the D input at the moment of a rising clock edge(or falling edge if the clock input is active low).It is called the D flip-flop for this reason,since the output takes the value of the D input or Data input,and Delays it by one clock count.The D flip-flop can be interpreted as a primitive memory cell,zero-order hold,or delay line.Figure 20-4 shows D flip-flop.Figure 20-4 D flip-flop 2021/9/1216电子技术专业英语教程D flip-flopTruth table:clockDQQprevRising edge00 xRising edge11xNon risingxQprevThese flip flops are very useful,as they form the basis for shift registers,which are an essential part of many electronic devices.The advantage of the D flip-flop over the D-type latch is that it captures the signal at the moment the clock goes high,and subsequent changes of the data line do not influence Q until the next rising clock edge.An exception is that some flip-flops have a reset signal input,which will reset Q(to zero),and may be either asynchronous or synchronous with the clock.2021/9/1217电子技术专业英语教程Vocabulary Acquisition stimulus margin evaluation ancillary briefStructureReading/writing techniquesLanguage in use2021/9/1218电子技术专业英语教程Vocabulary2021/9/1219电子技术专业英语教程Acquisition in dictionaryThe act of acquiring.获得，取得Something acquired,especially an addition to an established category or group.获得物The process of locating a satellite,guided missile,or moving target so that its track or orbit can be determined.搜索，探测2021/9/1220电子技术专业英语教程Acquisition in textAn acquisition instrument usually an oscilloscope or logic analyseris probably the first thing that comes to mind when you think about making electronic measurements.当进行电子测量时，人们首先想到的很可能是一件采集仪器通常是示波器或逻辑分析仪。2021/9/1221电子技术专业英语教程Acquisition in use aircraft target acquisition空中目标的搜索high-speed data acquisition高速数据采集language acquisition语言习得technique acquisition技术引进2021/9/1222电子技术专业英语教程Stimulus in dictionarySomething causing or regarded as causing a response.刺激因素An agent,an action,or a condition that elicits or accelerates a physiological or psychological activity or response.刺激物2021/9/1223电子技术专业英语教程Stimulus in textThe toolset for digital design characterization differs from its counterpart in analog/mixed signal design,but both must include stimulus instruments and acquisition instruments.The signal source,or signal generator,is the stimulus source that pairs with an acquisition instrument to create the two elements of a complete measurement solution.用于数字设计特性评价的测量仪器和用于模拟/混合信号设计的测量仪器是不一样的，但两者一定都包含激励信号产生仪器和信号采集仪器。信号源（或信号发生器）和采集仪器是构成一个完整测量解决方案的两大基本组成部分。2021/9/1224电子技术专业英语教程Stimulus in use under the stimulus of this hopeLight is a stimulus to growth in plants.2021/9/1225电子技术专业英语教程Margin in dictionaryAn edge and the area immediately adjacent to it;a border.边缘，边界The blank space bordering the written or printed area on a page.空白A limit in a condition or process,beyond or below which something is no longer possible or acceptable:极限the margin of realityhas crossed the margin of civilized behavior.2021/9/1226电子技术专业英语教程Margin in dictionaryAn amount allowed beyond what is needed:余地A measure,quantity,or degree of difference:差数The minimum return that an enterprise may earn and still pay for itself.边际收益The border of a leaf.树叶的边缘2021/9/1227电子技术专业英语教程Margin in dictionaryIn telegraphy,a measure of the ability of the receiving apparatus to copy with timing errors in the received signal.In printing,the space surrounding the type area,comprising head,tail,back and for edge.2021/9/1228电子技术专业英语教程Margin in textTo cite another example,engineers must characterize their emerging designs to ensure that the new hardware meets design specifications across the full range of operation and beyond.This is known as margin or limit testing.举另外一个例子。为了确保新硬件在整个操作范围及该范围之外满足性能设计要求，工程师们必须对即将完成的设计进行特性评价。这就是所谓的“边缘测试或极限测试”。2021/9/1229电子技术专业英语教程Margin in use by a comfortable margin以较大的多数by a narrow margin以微弱多数by a.margin以.之差2021/9/1230电子技术专业英语教程Margin in use binding margin装订边continental margin大陆边缘current margin工作电流范围,电流容限design margin设计余量error margin误差容限2021/9/1231电子技术专业英语教程Margin in use low level noise margin低电平噪声容限magnitude margin幅值裕度noise margin噪声容限,噪声安全系数nominal margin标称容限peak margin峰值容限2021/9/1232电子技术专业英语教程Evaluation in dictionaryA process to determine whether or not an item of hardware or software can perform a particular required function or to determine which of two or more items can perform the function best.评价；鉴定A process to reduce an expression to its simplest form or a single value.计算，求值2021/9/1233电子技术专业英语教程Evaluation in textA signal source is nothing less than the cornerstone of almost any instrumentation setup used in hardware design,debug,or evaluation projects 信号源是用于硬件设计、调试、评价工程中的几乎任何一种测量配置的基础。2021/9/1234电子技术专业英语教程Evaluation in use accomplishment evaluation学业成绩评定hazard evaluation危害评价loss evaluation损耗估算evaluation of determinants行列式的求值2021/9/1235电子技术专业英语教程Ancillary in dictionarySubordinate:从属的Auxiliary;helping:辅助的；补充的Something,such as a workbook,that is subordinate to something else,such as a textbook.附属物2021/9/1236电子技术专业英语教程Ancillary in text It can be very difficult to design an instrumentation-quality signal generator,and of course,the time spent designing ancillary test equipment is a costly distraction from the project itself.设计一个仪器级的信号发生器是非常困难的，而且设计辅助设备耗费的时间也将人们的宝贵精力从项目中分散开。2021/9/1237电子技术专业英语教程Brief in dictionaryShort in time,duration,length,or extent.短的Succinct;concise:简洁的；扼要的：Curt;abrupt.唐突的2021/9/1238电子技术专业英语教程Brief in dictionaryA short,succinct statement.简短，扼要的陈述A condensation or an abstract of a larger document or series of documents.概要，摘要2021/9/1239电子技术专业英语教程Brief in text Similarly,these fast AWGs with deep memory can generate very brief digital pulses and transients.同样，这些高速、大存储深度的 AWG能够产生非常短暂的数字脉冲和暂态波形。2021/9/1240电子技术专业英语教程Brief in use in brief简言之;以简洁的形式make brief of使简短brief and to the point简单扼要2021/9/1241电子技术专业英语教程Structure2021/9/1242电子技术专业英语教程Reading/Writing techniques2021/9/1243电子技术专业英语教程