Biomedical Engineering Reference
In-Depth Information
which can be re-written in a convenient form:
1 /R e 1 ( 1
+
L e 1 s/R e 1 )
Y N (s)
=
(5.30)
G e 1 /G e 1 C e 1 s
( 1 + 1 /G e 1 C e 1 s)R e 1 ( 1 + L e 1 s/R e 1 )
1
+
G e 1 /G e 1 C e 1 s
( 1
+
1 /G e 1 C e 1 s)R e 2 ( 1
+
L e 2 s/R e 2 )
1
+
G e 2 /G e 2 C e 2 s
( 1
+
1 /G e 2 C e 2 s)R e 2 ( 1
+
L e 2 s/R e 2 )
1
+
G e 2 /G e 2 C e 2 s
( 1
+
1 /G e 2 C e 2 s)R e 3 ( 1
+
L e 3 s/R e 3 )
...
1
+
...
G e(N 1 ) /G e(N 1 ) C e(N 1 ) s
( 1
+
1 /G e(N 1 ) C e(N 1 ) s)R eN ( 1
+
L eN s/R eN )
1
+
G eN /G eN C eN s
1
+
( 1
+
1 /G eN C eN s)R eN ( 1
+
L eN s/R eN )
We introduce the notation
W d (s) =
1
R e 1 C e 1 s ,
1
G e 1 C e 1 s
L e 1 s
R e 1
0 (s) =
and
W 1 (s) =
(5.31)
and replace the ratios in ( 5.30 ) and we obtain
1 /R e 1 ( 1
+
W 1 (s))
Y N (s)
=
(5.32)
W d (s)/(W 0 (s)
+
1 )
( 1
+
W 1 (s))
1
+
W d (s)/λ(W 0 (s)
+
1 )
( 1
+ W 1 (s)/αλ)
1
+
W d (s)/λχ(oW 0 (s)/χ +
1 )
( 1
+
W 1 (s)/αλ)
1
+
W d (s)/λ 2 χ(oW 0 (s)/χ +
1 )
+ W 1 (s)/α 2 λ 2 )
( 1
1
+
...
...
W d (s)/λ N 1 χ N 2 (o N 2 W 0 (s)/χ N 2
+
1 )
W 1 (s)/α N 1 λ N 1 )
( 1
+
1 +
W d (s)/λ N 1 χ N 1 (o N 1 W 0 (s)/χ N 1
+
1 )
1
+
W 1 (s)/α N 1 λ N 1 )
( 1
+
For the set of conditions from ( 5.18 ) and for
α
·
χ> 1
·
λ> 1 ,λ> 1 and χ
o, o > 1 ,
(5.33)
o N 1
we find that the term
(G e 1 C e 1 s)χ N 1 from ( 5.32 ) goes to zero as frequency increases.
In this case, the limit N
→∞
does not play any role, since χ
=
o ; however, if
1 /(G e 1 C e 1 s)
1 then we can then re-write ( 5.32 )as
Y N (s) =
1 /R e 1 ( 1
+
W 1 (s))
(5.34)
W d
1
+
W d
1 +
W d /χλ
1 +
W d /χλ 2
1
+
...
...
W d N 2 λ N 1
1
+
1
+ W d N 1 λ N 1
which is similar in form to ( 5.22 )
Y N (s)
1 /R e 1 ( 1
+
W 1 (s)))
(5.35)
1
+
g(W d (s), λ, χ)
in which
g W d (s), λ, χ =
W d (s)
(5.36)
W d (s)/λ
1
+
W d (s)/λχ
1
+
W d (s)λ 2 χ
···
1
+
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