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<div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626338a24c65f41259a16bbc/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">高速数字电路设计教材</div><div class="t m0 x2 h3 y2 ff2 fs1 fc0 sc1 ls1 ws0">yyyy-mm-dd<span class="_ _0"></span><span class="ff3 sc0 ls2">日期：<span class="_ _1"></span><span class="ls3">批准<span class="ff2 sc1 ls4">:</span></span></span></div><div class="t m0 x2 h3 y3 ff2 fs1 fc0 sc1 ls1 ws0">yyyy-mm-dd<span class="_ _0"></span><span class="ff3 sc0 ls2">日期：<span class="_ _1"></span><span class="ls3">审核<span class="ff2 sc1 ls4">:</span></span></span></div><div class="t m0 x2 h3 y4 ff2 fs1 fc0 sc1 ls1 ws0">yyyy-mm-dd<span class="_ _0"></span><span class="ff3 sc0 ls2">日期：<span class="_ _1"></span><span class="ls3">审核<span class="ff2 sc1 ls4">:</span></span></span></div><div class="t m0 x2 h3 y5 ff2 fs1 fc0 sc1 ls1 ws0">yyyy-mm-dd<span class="_ _0"></span><span class="ff3 sc0 ls2">日期：<span class="_ _1"></span><span class="ls3">拟制<span class="ff2 sc1 ls4">:</span></span></span></div><div class="t m0 x3 h4 y6 ff1 fs2 fc0 sc0 ls5 ws0">华为技术有限公司</div><div class="t m0 x4 h3 y7 ff3 fs1 fc0 sc0 ls6 ws0">版权所有<span class="ff2 sc1 ls4"> </span><span class="ls3">侵权必究</span></div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
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<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626338a24c65f41259a16bbc/bg2.jpg"><div class="t m0 x5 h5 y8 ff3 fs3 fc0 sc0 ls4 ws0">目<span class="ff2 sc1 ls7"> </span>录</div><div class="t m0 x6 h6 y9 ff4 fs4 fc0 sc1 ls8 ws0">49<span class="_ _2"></span><span class="ls9 ws1">4.5.3 Formulas Involving Twisted-pair Cable<span class="_ _3"> </span><span class="lsa ws0">........................................</span></span></div><div class="t m0 x6 h6 ya ff4 fs4 fc0 sc1 ls8 ws0">48<span class="_ _2"></span><span class="lsb ws2">4.5.2 Formulas Involving Coaxial Cable<span class="ff3 lsc ws0">（见<span class="_ _4"></span>图<span class="ff4 lsd">4.29</span><span class="ls4">）<span class="_ _5"> </span><span class="ff4 lsa">................................</span></span></span></span></div><div class="t m0 x6 h6 yb ff4 fs4 fc0 sc1 ls8 ws0">47<span class="_ _6"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _7"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span>.<span class="_ _7"></span>5<span class="_ _7"></span> S<span class="_ _7"></span>o<span class="_ _7"></span>f<span class="_ _7"></span>t<span class="_ _7"></span>w<span class="_ _7"></span>a<span class="_ _7"></span>r<span class="_ _8"></span>e<span class="_ _7"></span> f<span class="_ _8"></span>o<span class="_ _7"></span>r<span class="_ _7"></span> t<span class="_ _7"></span>r<span class="_ _7"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>s<span class="_ _7"></span>m<span class="_ _8"></span>i<span class="_ _7"></span>s<span class="_ _7"></span>s<span class="_ _7"></span>i<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span> l<span class="_ _7"></span>i<span class="_ _7"></span>n<span class="_ _7"></span>e<span class="_ _7"></span> c<span class="_ _7"></span>a<span class="_ _7"></span>l<span class="_ _7"></span>c<span class="_ _7"></span>u<span class="_ _7"></span>l<span class="_ _7"></span>a<span class="_ _7"></span>t<span class="_ _8"></span>i<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span>s<span class="_ _5"> </span>..................................</span></div><div class="t m0 x6 h6 yc ff4 fs4 fc0 sc1 ls8 ws0">46<span class="_ _6"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _8"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span>.<span class="_ _7"></span>4<span class="_ _7"></span> R<span class="_ _7"></span>e<span class="_ _7"></span>a<span class="_ _7"></span>s<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span>a<span class="_ _7"></span>b<span class="_ _7"></span>l<span class="_ _7"></span>e<span class="_ _7"></span> m<span class="_ _8"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>u<span class="_ _7"></span>f<span class="_ _7"></span>a<span class="_ _7"></span>c<span class="_ _7"></span>t<span class="_ _7"></span>u<span class="_ _7"></span>r<span class="_ _7"></span>i<span class="_ _7"></span>n<span class="_ _7"></span>g<span class="_ _7"></span> t<span class="_ _7"></span>o<span class="_ _7"></span>l<span class="_ _7"></span>e<span class="_ _7"></span>r<span class="_ _7"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>c<span class="_ _7"></span>e<span class="_ _8"></span>s<span class="_ _9"> </span>.......................................</span></div><div class="t m0 x6 h6 yd ff4 fs4 fc0 sc1 ls8 ws0">43<span class="_ _6"></span><span class="lse ws4">4.5.1.3 <span class="ff3 ls4 ws0">有效介电常数<span class="ff4 lsf">(Effective electric permittivity)<span class="_ _a"> </span><span class="lsa">................................</span></span></span></span></div><div class="t m0 x6 h6 ye ff4 fs4 fc0 sc1 ls8 ws0">41<span class="_ _6"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _8"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span>.<span class="_ _7"></span>2<span class="_ _7"></span> H<span class="_ _7"></span>o<span class="_ _7"></span>w<span class="_ _7"></span> p<span class="_ _7"></span>h<span class="_ _7"></span>y<span class="_ _7"></span>s<span class="_ _7"></span>i<span class="_ _7"></span>c<span class="_ _7"></span>a<span class="_ _8"></span>l<span class="_ _7"></span> d<span class="_ _7"></span>i<span class="_ _7"></span>m<span class="_ _7"></span>e<span class="_ _7"></span>n<span class="_ _7"></span>s<span class="_ _7"></span>i<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span>s<span class="_ _8"></span> a<span class="_ _7"></span>f<span class="_ _7"></span>f<span class="_ _7"></span>e<span class="_ _7"></span>c<span class="_ _7"></span>t<span class="_ _7"></span> i<span class="_ _7"></span>m<span class="_ _8"></span>p<span class="_ _7"></span>e<span class="_ _7"></span>d<span class="_ _7"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>c<span class="_ _7"></span>e<span class="_ _b"> </span>................................</span></div><div class="t m0 x6 h6 yf ff4 fs4 fc0 sc1 ls8 ws0">41<span class="_ _6"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _8"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span> H<span class="_ _7"></span>o<span class="_ _7"></span>w<span class="_ _7"></span> t<span class="_ _7"></span>i<span class="_ _7"></span>g<span class="_ _7"></span>h<span class="_ _7"></span>t<span class="_ _7"></span>l<span class="_ _7"></span>y<span class="_ _7"></span> m<span class="_ _8"></span>u<span class="_ _7"></span>s<span class="_ _7"></span>t<span class="_ _7"></span> w<span class="_ _7"></span>e<span class="_ _7"></span> c<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span>t<span class="_ _7"></span>r<span class="_ _8"></span>o<span class="_ _7"></span>l<span class="_ _7"></span> i<span class="_ _7"></span>m<span class="_ _7"></span>p<span class="_ _7"></span>e<span class="_ _7"></span>d<span class="_ _7"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>c<span class="_ _7"></span>e<span class="_"> </span>.....................................</span></div><div class="t m0 x6 h6 y10 ff4 fs4 fc0 sc1 ls8 ws0">41<span class="_ _2"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _8"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>1<span class="_ _7"></span> C<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span>t<span class="_ _7"></span>r<span class="_ _7"></span>o<span class="_ _7"></span>l<span class="_ _7"></span> o<span class="_ _7"></span>f<span class="_ _7"></span> T<span class="_ _7"></span>r<span class="_ _7"></span>a<span class="_ _7"></span>n<span class="_ _7"></span>s<span class="_ _7"></span>m<span class="_ _8"></span>i<span class="_ _7"></span>s<span class="_ _7"></span>s<span class="_ _7"></span>i<span class="_ _7"></span>o<span class="_ _7"></span>n<span class="_ _7"></span> L<span class="_ _8"></span>i<span class="_ _7"></span>n<span class="_ _7"></span>e<span class="_ _7"></span> P<span class="_ _7"></span>a<span class="_ _7"></span>r<span class="_ _7"></span>a<span class="_ _7"></span>m<span class="_ _8"></span>e<span class="_ _7"></span>t<span class="_ _7"></span>e<span class="_ _7"></span>r<span class="_ _7"></span>s<span class="_ _9"> </span>......................................</span></div><div class="t m0 x6 h6 y11 ff4 fs4 fc0 sc1 ls8 ws0">39<span class="_ _c"></span><span class="ls10 ws5">4.5 LINE IMPEDANCE AND PROPAGATION DELAY<span class="_ _a"> </span><span class="lsa ws0">................................</span></span></div><div class="t m0 x6 h6 y12 ff4 fs4 fc0 sc1 ls8 ws0">38<span class="_ _2"></span><span class="ls11 ws6">4.4.5 <span class="ff3 lsc ws0">延迟线<span class="_ _d"> </span><span class="ff4 lsa">.................................................................</span></span></span></div><div class="t m0 x6 h6 y13 ff4 fs4 fc0 sc1 ls8 ws0">36<span class="_ _2"></span><span class="ls11 ws6">4.4.4 <span class="ff3 ls4 ws0">直角弯曲布线<span class="_ _e"> </span><span class="ff4 lsa">...........................................................</span></span></span></div><div class="t m0 x6 h6 y14 ff4 fs4 fc0 sc1 ls8 ws0">36<span class="_ _6"></span><span class="lse ws4">4.4.3.1 <span class="ff3 ls4 ws0">均匀负载总线的阻抗特性<span class="_ _a"> </span><span class="ff4 lsa">...............................................</span></span></span></div><div class="t m0 x6 h6 y15 ff4 fs4 fc0 sc1 ls8 ws0">35<span class="_ _2"></span><span class="ls11 ws6">4.4.3 <span class="ff3 ls4 ws0">等间隔的容性负载<span class="_ _e"> </span><span class="ff4 lsa">.......................................................</span></span></span></div><div class="t m0 x6 h6 y16 ff4 fs4 fc0 sc1 ls8 ws0">35<span class="_ _6"></span><span class="lse">4.4.2.2 <span class="ff3 ls4">容性负载对传输信号的影响<span class="_ _e"> </span></span><span class="lsa">.............................................</span></span></div><div class="t m0 x6 h6 y17 ff4 fs4 fc0 sc1 ls8 ws0">33<span class="_ _6"></span><span class="lse ws4">4.4.2.1 <span class="ff3 ls4 ws0">来自容性负载的信号反射<span class="_ _a"> </span><span class="ff4 lsa">...............................................</span></span></span></div><div class="t m0 x6 h6 y18 ff4 fs4 fc0 sc1 ls8 ws0">32<span class="_ _2"></span><span class="ls11 ws6">4.4.2 <span class="ff3 ls4 ws0">传输线中点的容性负载<span class="_ _e"> </span><span class="ff4 lsa">...................................................</span></span></span></div><div class="t m0 x6 h6 y19 ff4 fs4 fc0 sc1 ls8 ws0">32<span class="_ _6"></span><span class="lse ws4">4.4.1.2 <span class="ff3 ls4 ws0">高阻抗输出驱动无匹配传输线<span class="_ _a"> </span><span class="ff4 lsa">...........................................</span></span></span></div><div class="t m0 x6 h6 y1a ff4 fs4 fc0 sc1 ls8 ws0">31<span class="_ _6"></span><span class="lse ws4">4.4.1.1 <span class="ff3 ls4 ws0">低阻抗输出驱动无匹配传输线<span class="_ _a"> </span><span class="ff4 lsa">...........................................</span></span></span></div><div class="t m0 x6 h6 y1b ff4 fs4 fc0 sc1 ls8 ws0">31<span class="_ _2"></span><span class="ls11 ws6">4.4.1 <span class="ff3 ls4 ws0">无匹配线<span class="_ _d"> </span><span class="ff4 lsa">...............................................................</span></span></span></div><div class="t m0 x6 h6 y1c ff4 fs4 fc0 sc1 ls8 ws0">31<span class="_ _c"></span><span class="lsd ws7">4.4 <span class="ff3 ls4 ws0">特殊传输线<span class="_ _b"> </span><span class="ff4 lsa">.................................................................</span></span></span></div><div class="t m0 x6 h6 y1d ff4 fs4 fc0 sc1 ls8 ws0">30<span class="_ _2"></span><span class="ls11 ws6">4.3.5 <span class="ff3 ls4 ws0">传输线匹配不好时的建立时间<span class="_ _f"> </span><span class="ff4 lsa">.............................................</span></span></span></div><div class="t m0 x6 h6 y1e ff4 fs4 fc0 sc1 ls8 ws0">30<span class="_ _2"></span><span class="ls11 ws6">4.3.4 <span class="ff3 ls4 ws0">缩短线长<span class="_ _d"> </span><span class="ff4 lsa">...............................................................</span></span></span></div><div class="t m0 x6 h6 y1f ff4 fs4 fc0 sc1 ls8 ws0">30<span class="_ _2"></span><span class="ls11 ws6">4.3.3 <span class="ff3 ls4 ws0">源端匹配<span class="_ _d"> </span><span class="ff4 lsa">...............................................................</span></span></span></div><div class="t m0 x6 h6 y20 ff4 fs4 fc0 sc1 ls8 ws0">26<span class="_ _2"></span><span class="ls11 ws6">4.3.2 <span class="ff3 ls4 ws0">终端匹配<span class="_ _d"> </span><span class="ff4 lsa">...............................................................</span></span></span></div><div class="t m0 x6 h6 y21 ff4 fs4 fc0 sc1 ls8 ws0">26<span class="_ _2"></span><span class="ls11 ws6">4.3.1 <span class="ff3 ls4 ws0">传输线的反射<span class="_ _e"> </span><span class="ff4 lsa">...........................................................</span></span></span></div><div class="t m0 x6 h6 y22 ff4 fs4 fc0 sc1 ls8 ws0">25<span class="_ _c"></span><span class="lsd ws7">4.3 <span class="ff3 ls4 ws0">源阻抗和负载阻抗的影响<span class="_ _b"> </span><span class="ff4 lsa">.....................................................</span></span></span></div><div class="t m0 x6 h6 y23 ff4 fs4 fc0 sc1 ls8 ws0">24<span class="_ _2"></span><span class="ls11 ws6">4.2.5 <span class="ff3 ls4 ws0">绝缘损耗</span><span class="lsa ws8"> ...............................................................</span></span></div><div class="t m0 x6 h6 y24 ff4 fs4 fc0 sc1 ls8 ws0">24<span class="_ _2"></span><span class="ls11 ws6">4.2.4 </span></div><div class="t m0 x7 h6 y25 ff3 fs4 fc0 sc1 ls4 ws0">补偿效应<span class="ff4 lsa ws8"> ...............................................................</span></div><div class="t m0 x6 h6 y26 ff4 fs4 fc0 sc1 ls8 ws0">22<span class="_ _6"></span><span class="lse ws4">4.2.3.3 <span class="ff3 ls4 ws0">趋肤效应区域的传输线阻抗<span class="_ _a"> </span><span class="ff4 lsa">.............................................</span></span></span></div><div class="t m0 x6 h6 y27 ff4 fs4 fc0 sc1 ls8 ws0">19<span class="_ _6"></span><span class="lse ws4">4.2.3.2 <span class="ff3 ls4 ws0">趋肤效应区域的频率响应<span class="_ _a"> </span><span class="ff4 lsa">...............................................</span></span></span></div><div class="t m0 x6 h6 y28 ff4 fs4 fc0 sc1 ls8 ws0">18<span class="_ _6"></span><span class="lse ws4">4.2.3.1 <span class="ff3 ls4 ws0">趋肤效应的空间分布<span class="_ _a"> </span><span class="ff4 lsa">...................................................</span></span></span></div><div class="t m0 x6 h6 y29 ff4 fs4 fc0 sc1 ls8 ws0">17<span class="_ _2"></span><span class="ls11 ws6">4.2.3 <span class="ff3 ls4 ws0">趋肤效应<span class="_ _d"> </span><span class="ff4 lsa">...............................................................</span></span></span></div><div class="t m0 x6 h6 y2a ff4 fs4 fc0 sc1 ls8 ws0">15<span class="_ _6"></span><span class="ls12 ws9">4.2.2.2 RC<span class="ff3 ls4 ws0">传输线<span class="_ _10"> </span><span class="ff4 lsa">............................................................</span></span></span></div><div class="t m0 x6 h6 y2b ff4 fs4 fc0 sc1 ls8 ws0">13<span class="_ _6"></span><span class="lse">4.2.2.1 <span class="ff3 ls4">低损耗的传输线<span class="_ _d"> </span></span><span class="lsa">.......................................................</span></span></div><div class="t m0 x8 h6 y2c ff4 fs4 fc0 sc1 ls4 ws0">9<span class="_ _2"></span><span class="ls11 ws6">4.2.2 <span class="ff3 ls4 ws0">有损耗的传输线<span class="_ _e"> </span><span class="ff4 lsa">..........................................................</span></span></span></div><div class="t m0 x8 h6 y2d ff4 fs4 fc0 sc1 ls4 ws0">9<span class="_ _2"></span><span class="ls11 ws6">4.2.1 <span class="ff3 ls4 ws0">理想的无失真、无损耗传输线<span class="_ _f"> </span><span class="ff4 lsa">..............................................</span></span></span></div><div class="t m0 x8 h6 y2e ff4 fs4 fc0 sc1 ls4 ws0">7<span class="_ _c"></span><span class="lsd ws7">4.2 <span class="ff3 ls4 ws0">无限长传输线<span class="_ _b"> </span><span class="ff4 lsa">................................................................</span></span></span></div><div class="t m0 x8 h6 y2f ff4 fs4 fc0 sc1 ls4 ws0">6<span class="_ _2"></span><span class="ls11 ws6">4.1.3 <span class="ff3 ls4 ws0">直连导线的串扰<span class="_ _e"> </span><span class="ff4 lsa">..........................................................</span></span></span></div><div class="t m0 x8 h6 y30 ff4 fs4 fc0 sc1 ls4 ws0">4<span class="_ _2"></span><span class="ls11 ws6">4.1.2 <span class="ff3 ls4 ws0">直连导线的<span class="ff4 lsa">E<span class="_ _7"></span>M<span class="_ _7"></span>I<span class="_ _11"> </span>...........................................................</span></span></span></div><div class="t m0 x8 h6 y31 ff4 fs4 fc0 sc1 ls4 ws0">4<span class="_ _2"></span><span class="ls11">4.1.1 <span class="ff3 ls4">直连导线的信号失真<span class="_ _12"> </span></span><span class="lsa">.......................................................</span></span></div><div class="t m0 x8 h6 y32 ff4 fs4 fc0 sc1 ls4 ws0">3<span class="_ _c"></span><span class="lsd">4.1 <span class="ff3 ls4">普通直连导线的缺点<span class="_ _13"> </span></span><span class="lsa">..........................................................</span></span></div><div class="t m0 x8 h6 y33 ff4 fs4 fc0 sc1 ls4 ws0">2<span class="_ _14"></span><span class="ff3">第<span class="ff4">4</span><span class="lsc">章　传输线<span class="_ _10"> </span><span class="ff4 lsa">....................................................................</span></span></span></div><div class="t m0 x9 h7 y34 ff3 fs5 fc0 sc1 ls4 ws0">内部公开</div><div class="t m0 xa h7 y35 ff3 fs5 fc0 sc1 ls4 ws0">高速数字电路设计</div><div class="t m0 xb h8 y36 ff4 fs5 fc0 sc1 ls13 ws0">2001-09-01<span class="_ _15"> </span><span class="ff3 ls4">版权所有，侵权必究<span class="_ _16"> </span>第<span class="ff4">2</span>页，共<span class="ff4">50</span>页</span></div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626338a24c65f41259a16bbc/bg3.jpg"><div class="t m0 x6 h6 y37 ff4 fs4 fc0 sc1 ls8 ws0">49<span class="_ _2"></span><span class="lsa ws3">4<span class="_ _7"></span>.<span class="_ _8"></span>5<span class="_ _7"></span>.<span class="_ _7"></span>4<span class="_ _7"></span> s<span class="_ _7"></span>i<span class="_ _7"></span>m<span class="_ _7"></span>p<span class="_ _7"></span>l<span class="_ _7"></span>e<span class="_ _7"></span> f<span class="_ _8"></span>o<span class="_ _7"></span>r<span class="_ _7"></span>m<span class="_ _7"></span>u<span class="_ _7"></span>l<span class="_ _7"></span>a<span class="_ _7"></span>s<span class="_ _8"></span> s<span class="_ _7"></span>e<span class="_ _7"></span>t<span class="_ _7"></span> f<span class="_ _7"></span>o<span class="_ _7"></span>r<span class="_ _7"></span> m<span class="_ _8"></span>i<span class="_ _7"></span>c<span class="_ _7"></span>r<span class="_ _7"></span>o<span class="_ _7"></span>s<span class="_ _7"></span>t<span class="_ _7"></span>r<span class="_ _7"></span>i<span class="_ _7"></span>p<span class="_ _7"></span>s<span class="_ _17"> </span>...........................................</span></div><div class="t m0 x9 h7 y34 ff3 fs5 fc0 sc1 ls4 ws0">内部公开</div><div class="t m0 xa h7 y35 ff3 fs5 fc0 sc1 ls4 ws0">高速数字电路设计</div><div class="t m0 xb h8 y36 ff4 fs5 fc0 sc1 ls13 ws0">2001-09-01<span class="_ _15"> </span><span class="ff3 ls4">版权所有，侵权必究<span class="_ _16"> </span>第<span class="ff4">3</span>页，共<span class="ff4">50</span>页</span></div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626338a24c65f41259a16bbc/bg4.jpg"><div class="t m0 xc h5 y38 ff3 fs3 fc0 sc0 ls4 ws0">第<span class="ff2 sc1">4</span><span class="ls14">章　传输线</span></div><div class="t m0 xb h9 y39 ff3 fs1 fc0 sc0 ls2 ws0">摘要<span class="fs4 sc1 ls4">：</span></div><div class="t m0 xd h6 y3a ff3 fs4 fc0 sc1 ls4 ws0">在高频数字电路中，传输线的性能优于普通的直连导线，主要体现在：<span class="ff4">1</span>、信号变形小；<span class="ff4">2</span>、</div><div class="t m0 xb h6 y3b ff3 fs4 fc0 sc1 ls4 ws0">电磁干扰很小；<span class="ff4">3</span>、信号串扰少。</div><div class="t m0 xd ha y3c ff3 fs4 fc0 sc1 ls15 ws0">同时传输线也有它的缺点，例如需要更高的驱动功率，但在高速数字电路中，信号的性能是</div><div class="t m0 xb ha y3d ff3 fs4 fc0 sc1 ls4 ws0">最重要的，因此传输线的使用也是必然的。</div><div class="t m0 xd ha y3e ff3 fs4 fc0 sc1 ls4 ws0">本章描述了传输线的基本概念，并将传输线与普通的直连导线进行对比，给出了线路阻抗的</div><div class="t m0 xb ha y3f ff3 fs4 fc0 sc1 ls4 ws0">计算方法及其对信号质量的影响。</div><div class="t m0 xb hb y40 ff5 fs1 fc1 sc1 ls16 ws0">4.1 <span class="ff3 fc0 sc0 ls2">普通直连导线的缺点</span></div><div class="t m0 xd h6 y41 ff4 fs4 fc0 sc1 ls17 ws0">NEWCO<span class="ff3 ls4">公司曾经为其高速处理器建立过一个模型，</span>NEWCO<span class="ff3 ls4">认为使用</span><span class="ls18">PCB<span class="ff3 ls4">不仅成本很高，而</span></span></div><div class="t m0 xb h6 y42 ff3 fs4 fc0 sc1 ls4 ws0">且<span class="ff4 ls18">PCB</span>的生产也需要花很长时间，因此<span class="ff4 ls19">NECO</span>使用直连导线技术。该模型建立在一块<span class="ff4 ls1a">16in.X20in.</span>的</div><div class="t m0 xb h6 y43 ff3 fs4 fc0 sc1 ls4 ws0">电路板上，内含<span class="ff4 ls8">600</span>多个门电路，<span class="ff4 ls8">2000</span>多个网络，以下列出了这些信号网络的特性：</div><div class="t m0 xd h6 y44 ff4 fs4 fc0 sc1 ls8 ws0">1.<span class="ff3 ls4">网络数目：<span class="_ _18"> </span></span><span class="ls9 ws1"> 2000</span></div><div class="t m0 xd h6 y45 ff4 fs4 fc0 sc1 ls8 ws0">2.<span class="ff3 ls4">平均网络长度：<span class="_ _19"> </span></span><span class="ls9 ws1"> 4in.</span><span class="ff3 ls4">（没有终端匹配）</span></div><div class="t m0 xd h6 y46 ff4 fs4 fc0 sc1 ls8 ws0">3.<span class="ff3 ls4">线路平均高出地平面的高度：</span><span class="ls11 ws6"> 0.2in.</span></div><div class="t m0 xd h6 y47 ff4 fs4 fc0 sc1 ls8 ws0">4.<span class="ff3 lsc">线宽（</span><span class="ls1b">AWG30<span class="ff3 ls4">）：<span class="_ _1a"> </span></span><span class="lsf"> <span class="ff3 lsc">直径</span><span class="ls1a">0.01in.</span></span></span></div><div class="t m0 xd h6 y48 ff4 fs4 fc0 sc1 ls8 ws0">5.<span class="ff3 ls4">信号上升时间：<span class="_ _19"> </span></span><span class="ls9 ws1"> 2.0ns</span></div><div class="t m0 xd h6 y49 ff4 fs4 fc0 sc1 ls8 ws0">6.<span class="ff3 lsc">拐点（</span><span class="ls18">Knee<span class="ff3 ls4">）频率（式</span><span class="ls1c">1.1<span class="ff3 ls4">）：</span><span class="lsd">250MHz=0.5/2.0ns</span></span></span></div><div class="t m0 xd ha y4a ff3 fs4 fc0 sc1 ls4 ws0">下面我们来分析一下这个模型的性能：</div><div class="t m0 xb hc y4b ff4 fs1 fc0 sc1 ls4 ws0">4.1.1 <span class="ff3">直连导线的信号失真</span></div><div class="t m0 xd h6 y4c ff4 fs4 fc0 sc1 ls17 ws0">NEWCO<span class="ff3 ls4">预计信号的上升时间为</span><span class="lsd ws7"> 2ns</span><span class="ff3 ls4">，<span class="ff4"> </span>对应的线长为（参考式</span><span class="ls1c">1.3<span class="ff3 lsc">）：</span></span></div><div class="t m0 xd ha y4d ff3 fs4 fc0 sc1 ls4 ws0">而区分集中参数或者分布参数电路的临界参数为：</div><div class="t m0 xd h6 y4e ff4 fs4 fc0 sc1 ls17 ws0">NEWCO<span class="ff3 lsc">认为，由于模型的平均线长接近该临界参数，他们的模型基本上是一<span class="_ _1b"></span>个集中的模型，</span></div><div class="t m0 xb ha y4f ff3 fs4 fc0 sc1 ls4 ws0">因此电路不会出现或者只是轻微的振铃，实际结果表明这种预测是错误的。</div><div class="t m0 xd ha y50 ff3 fs4 fc0 sc1 ls15 ws0">集中参数电路很少振铃，分布式电路在没有做好匹配的情况下通常都会出现振铃，这是受电</div><div class="t m0 xb h6 y51 ff3 fs4 fc0 sc1 ls4 ws0">路的<span class="ff4">Q</span>值影响的。电路的<span class="ff4">Q</span>值<span class="_ _1b"></span>代表信号在电路中衰减的<span class="_ _1b"></span>速度，低<span class="ff4">Q</span>电路的信号衰减很<span class="_ _1b"></span>快，高<span class="ff4">Q</span><span class="lsc">电路的</span></div><div class="t m0 xb ha y52 ff3 fs4 fc0 sc1 ls4 ws0">信号则衰减很慢，从而有更大机会产生振铃。</div><div class="t m0 xd h6 y53 ff3 fs4 fc0 sc1 ls1d ws0">电路的<span class="ff4 ls4">Q</span><span class="ls1e">值是单位振荡频率下能量的储存量与丢失量之比，已知<span class="ff4 ls4">Q</span>值的电路的过冲最大值可以</span></div><div class="t m0 xb h6 y54 ff3 fs4 fc0 sc1 ls4 ws0">由式<span class="ff4 ls1c">4.3</span><span class="lsc">估算：</span></div><div class="t m0 x9 h7 y34 ff3 fs5 fc0 sc1 ls4 ws0">内部公开</div><div class="t m0 xa h7 y35 ff3 fs5 fc0 sc1 ls4 ws0">高速数字电路设计</div><div class="t m0 xb h8 y36 ff4 fs5 fc0 sc1 ls13 ws0">2001-09-01<span class="_ _15"> </span><span class="ff3 ls4">版权所有，侵权必究<span class="_ _16"> </span>第<span class="ff4">4</span>页，共<span class="ff4">50</span>页</span></div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf5" class="pf w0 h0" data-page-no="5"><div class="pc pc5 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626338a24c65f41259a16bbc/bg5.jpg"><div class="t m0 xd h6 y55 ff3 fs4 fc0 sc1 lsc ws0">这里，<span class="ff4 ls1f wsa">Vovershoot = </span><span class="ls4">信号上冲幅度，单位<span class="ff4">V</span>；</span></div><div class="t m0 xd hd y56 ff4 fs6 fc0 sc1 ls20 wsb"> <span class="fs4 ls21 wsc"> Vstep = <span class="ff3 ls4 ws0">期望的稳定电压输出，单位<span class="ff4">V</span>；</span></span></div><div class="t m0 xd h6 y57 ff4 fs4 fc0 sc1 ls22 wsd"> Q = <span class="ff3 ls4 ws0">谐振参数（假设<span class="ff4 lsb">>0.5</span><span class="lsc">）。</span></span></div><div class="t m0 xd h6 y58 ff3 fs4 fc0 sc1 ls4 ws0">一个典型的例子是如图<span class="ff4 ls1c">4.1</span>所示的二阶电路，衰减常数为<span class="ff4 ls23">2L/R</span>，严格遵循式<span class="ff4 ls1c">4.3</span>。</div><div class="t m0 xd h6 y59 ff3 fs4 fc0 sc1 lsc ws0">从经验上来讲，对于理想<span class="_ _4"></span>的阶跃冲激源输入，<span class="_ _4"></span><span class="ff4 ls4">Q<span class="ff3">为</span>1<span class="ff3 lsc">的数字电路会产生</span><span class="ls8">16%<span class="ff3 lsc">的过冲，如果<span class="_ _4"></span><span class="ff4 ls4">Q<span class="ff3 lsc">值上</span></span></span></span></span></div><div class="t m0 xb h6 y5a ff3 fs4 fc0 sc1 ls4 ws0">升到<span class="ff4">2</span>，则过冲增加到<span class="ff4 ls8">44%</span>，<span class="ff4">Q</span>值低于<span class="ff4 ls1c">0.5</span>的数字电路则很少产生过冲或者振铃。</div><div class="t m0 xd h6 y5b ff3 fs4 fc0 sc1 lsc ws0">当电路的感抗已知时，很容易计算电路<span class="ff4 ls4">Q</span>值。直连导线的<span class="_ _4"></span>最基本的问题就在于感抗太高，电路</div><div class="t m0 xb h6 y5c ff3 fs4 fc0 sc1 ls4 ws0">的线路感抗高，容性负载比较大，导致电路的<span class="ff4">Q</span>值就相对较高。</div><div class="t m0 xd h6 y5d ff3 fs4 fc0 sc1 ls4 ws0">我们可以计算一下<span class="ff4 ls17">NEWCO</span>模型的线路感抗（参考附录<span class="ff4">C</span>中的公式）：</div><div class="t m0 x9 h7 y34 ff3 fs5 fc0 sc1 ls4 ws0">内部公开</div><div class="t m0 xa h7 y35 ff3 fs5 fc0 sc1 ls4 ws0">高速数字电路设计</div><div class="t m0 xb h8 y36 ff4 fs5 fc0 sc1 ls13 ws0">2001-09-01<span class="_ _15"> </span><span class="ff3 ls4">版权所有，侵权必究<span class="_ _16"> </span>第<span class="ff4">5</span>页，共<span class="ff4">50</span>页</span></div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
