SP8861 Mitel Networks, SP8861 Datasheet - Page 11

• Manufacturer Part Number: SP8861
• Description: 13GHz Low Power Single-Chip Frequency Synthesiser
• Manufacturer: Mitel Networks

where K
loop and F
values can now be substituted in equation (3) to obtain a value
for C
and R
Example
for the second order loop and F
From equation (5):
From equation (4):
Using these values in equation (3):
Now, since
Calculate values for a third order loop with parameters as
1
2
and in equations (4) and (5) to determine values for C
CHARGE
.
Fig. 11 Standard form of third order loop filter
FROM
PUMP
u
, K
0
0
where A =
t
is the phase margin, normally set to 45 . These
, N and
1
= C
t
t
t
t
t
t
t
C
1
2
3
2
1
1
1
3
R
1
= 768·7 s
=
=
=
=
=
=
= 131·8 s
= 15·3 s
= 6·334310
v
1
= 0·0153 F
R1
2tan 45 1
0·4142
11(50032p)
11(50032p)
7·896110
3161·6
n
500141·6
7·96310
and R
(500323p)
11
11
are as defined for the second order
500Hz32 p
v
v
80003(50032p)
n
n
2
2
C1
1
t
t
= 1k , C
2
3
2
2
0
23
10
cos 45
26
= 45 .
32p310MHz/V
1·1714
32·415
2
2
2
6·832
C2
1
1
31·318310
R2
3(7·687310
3(1·318310
1
1·53310
=
1
2
10
2
3
TO VCO
24
24
24
25
3[A]
)
)
2
2
1
2
2
For Fig. 11,
For Fig. 12,
Substituting for C
For Fig. 12,
components, either can be chosen and the other determined.
Assuming that R
CHARGE
Since the values of C
FROM
PUMP
Fig. 12 Modified form of third order loop filter
or, R
or, C
or, R
C
C
2
2
3
R1
C
2
R
t
=
t
t
t
t
C
t
R
t
= 0·01318 F
= 1k , then
:
2
2
2
3
2
2
3
2
3
1
1
2
1
2
1·318310
=
= R
=
=
= C
= 3·17nF
=
= C
=
= C
= R
= C
= C
= 0·0153nF
= 41·627k
= 50·242k
7·687310
1·318310
7·687310
1·53310
t
1·53310
10
2
2
C1
2
2
1
2
2
2
1
C
2
R
41627
R
R
and R
R
R
( C
3
1
10
C
2
2
3
2
t
1
1
1
3
=
0·0153310
1
3
1 C
24
t
R
t
R
3
3
Cx
R2
2
25
3
28
2
24
24
are independent of the other
2
24
)
21·318310
= R
2
26
C
R3
1
1
t
3
24
C3
SP8861
TO VCO
11