ch17.1.htm
来自「介绍asci设计的一本书」· HTM 代码 · 共 2,690 行 · 第 1/5 页
HTM
2,690 行
1</SUB>
+ <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
3</SUB>
+ <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
4</SUB>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=81869">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=81871">
</A>
</P>
</TD>
</TR>
</TABLE>
<P CLASS="BodyAfterHead">
<A NAME="pgfId=35841">
</A>
In Eq. <A HREF="CH17.1.htm#17606" CLASS="XRef">
17.2</A>
notice that <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
24</SUB>
= <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
+ <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
1</SUB>
(and not <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
+ <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
1</SUB>
+ <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
2</SUB>
) because <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
1</SUB>
is the resistance to <SPAN CLASS="EquationVariables">
V</SPAN>
<SUB CLASS="Subscript">
0</SUB>
(ground) shared by node 2 and node 4.</P>
<P CLASS="Body">
<A NAME="pgfId=65545">
</A>
Suppose we have the following parameters (from the generic 0.5 <SPAN CLASS="Symbol">
m</SPAN>
m CMOS process, G5) for the layout shown in <A HREF="CH17.1.htm#28148" CLASS="XRef">
Figure 17.3</A>
(b):</P>
<UL>
<LI CLASS="BulletFirst">
<A NAME="pgfId=34556">
</A>
m2 resistance is 50 m<SPAN CLASS="Symbol">
W</SPAN>
/square.</LI>
<LI CLASS="BulletList">
<A NAME="pgfId=34560">
</A>
m2 capacitance (for a minimum-width line) is 0.2 pFmm<SUP CLASS="Superscript">
–1</SUP>
.</LI>
<LI CLASS="BulletList">
<A NAME="pgfId=34561">
</A>
4X inverter delay is 0.02 ns + 0.5<SPAN CLASS="EquationVariables">
C</SPAN>
<SUB CLASS="SubscriptVariable">
L</SUB>
ns (<SPAN CLASS="EquationVariables">
C</SPAN>
<SUB CLASS="SubscriptVariable">
L</SUB>
is in picofarads).</LI>
<LI CLASS="BulletList">
<A NAME="pgfId=39326">
</A>
Delay is measured using 0.35/0.65 output trip points.</LI>
<LI CLASS="BulletList">
<A NAME="pgfId=34562">
</A>
m2 minimum width is 3 <SPAN CLASS="Symbol">
l</SPAN>
= 0.9 <SPAN CLASS="Symbol">
m</SPAN>
m.</LI>
<LI CLASS="BulletLast">
<A NAME="pgfId=34563">
</A>
1X inverter input capacitance is 0.02 pF (a standard load).</LI>
</UL>
<P CLASS="Body">
<A NAME="pgfId=37695">
</A>
First we need to find the pull-down resistance, <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
, of the 4X inverter. If we model the gate with a linear pull-down resistor, <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
, driving a load <SPAN CLASS="EquationVariables">
C</SPAN>
<SUB CLASS="SubscriptVariable">
L</SUB>
, the output waveform is exp –<SPAN CLASS="EquationVariables">
t</SPAN>
/(<SPAN CLASS="EquationVariables">
C</SPAN>
<SUB CLASS="SubscriptVariable">
L</SUB>
<SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
) (normalized to 1V). The output reaches 63 percent of its final value when <SPAN CLASS="EquationVariables">
t</SPAN>
= <SPAN CLASS="EquationVariables">
C</SPAN>
<SUB CLASS="SubscriptVariable">
L</SUB>
<SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
, because exp (–1) = 0.63. Then, because the delay is measured with a 0.65 trip point, the constant 0.5 nspF <SUP CLASS="Superscript">
–1</SUP>
= 0.5 k<SPAN CLASS="Symbol">
W</SPAN>
is very close to the equivalent pull-down resistance. Thus, <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="SubscriptVariable">
pd</SUB>
<SPAN CLASS="Symbol">
ª</SPAN>
500 <SPAN CLASS="Symbol">
W</SPAN>
.</P>
<P CLASS="Body">
<A NAME="pgfId=86754">
</A>
From the given data, we can calculate the <SPAN CLASS="EquationVariables">
R</SPAN>
’s and <SPAN CLASS="EquationVariables">
C</SPAN>
’s: </P>
<TABLE>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86550">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86552">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86554">
</A>
(0.1 mm) (50 <SPAN CLASS="Symbol">
¥</SPAN>
10<SUP CLASS="Superscript">
–3</SUP>
<SPAN CLASS="Symbol">
W</SPAN>
)</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86556">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86558">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86560">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86562">
</A>
<SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
1</SUB>
= <SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
2</SUB>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86564">
</A>
=</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86566">
</A>
––––––––––––––––––––</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86568">
</A>
=</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86570">
</A>
6 <SPAN CLASS="Symbol">
W</SPAN>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86572">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86574">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86576">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86578">
</A>
0.9 <SPAN CLASS="Symbol">
m</SPAN>
m</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86580">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86582">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86584">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86586">
</A>
<SUB CLASS="Subscript">
</SUB>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86588">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86590">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86592">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86594">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86596">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86598">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86600">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86602">
</A>
(1 mm) (50 <SPAN CLASS="Symbol">
¥</SPAN>
10<SUP CLASS="Superscript">
–3</SUP>
<SPAN CLASS="Symbol">
W</SPAN>
)</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86604">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86606">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86608">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86610">
</A>
<SPAN CLASS="EquationVariables">
R</SPAN>
<SUB CLASS="Subscript">
3</SUB>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86612">
</A>
=</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86614">
</A>
––––––––––––––––––––</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86616">
</A>
=</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86618">
</A>
56 <SPAN CLASS="Symbol">
W</SPAN>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86620">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86622">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86624">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86626">
</A>
0.9 <SPAN CLASS="Symbol">
m</SPAN>
m</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86628">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86630">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86632">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86634">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86636">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86638">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86640">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnLeft">
<A NAME="pgfId=86642">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqn">
<A NAME="pgfId=86644">
</A>
</P>
</TD>
</TR>
<TR>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnRight">
<A NAME="pgfId=86646">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86648">
</A>
</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86650">
</A>
(2 mm) (50 <SPAN CLASS="Symbol">
¥</SPAN>
10<SUP CLASS="Superscript">
–3</SUP>
<SPAN CLASS="Symbol">
W</SPAN>
)</P>
</TD>
<TD ROWSPAN="1" COLSPAN="1">
<P CLASS="TableEqnCenter">
<A NAME="pgfId=86652">
</A>
</P>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?