SAW Components
Low-loss Filter
Data Sheet
B3751
315,00 MHz
Ceramic package
QCC8C
Features
s
RF low-loss filter for remote control receivers
s
Package for
Surface Mounted Technology
(SMT)
s
Balanced and unbalanced operation possible
s
Protection layer: Protec
Terminals
s
Ni, gold plated
typ. dimensions in mm, approx. weight 0,1 g
Pin configuration
1
2
5
6
4,8
3,7
Input Ground
Input
Output
Output Ground
Case - Ground
to be grounded
Type
B3751
Ordering code
B39321-B3751-U310
Marking and package
according to
C61157-A7-A56
Packing
according to
F61074-V8070-Z000
Electrostactic Sensitive Device
(ESD)
Maximum ratings
Operable temperature range
Storage temperature range
DC voltage
Source power
T
A
T
stg
V
DC
P
S
–45/+120
–45/+120
6
10
˚C
˚C
V
dBm
source impedance 50
Ω
2
Mar 13, 2003
SAW Components
Low-loss Filter
Data Sheet
Characteristics
Reference temperature:
Terminating source impedance:
Terminating load impedance:
B3751
315,00 MHz
T
A
= –45 ... +95˚C
Z
S
= 50
Ω
and matching network
Z
L
= 50
Ω
and matching network
min.
typ.
315,00
max.
—
MHz
Center frequency
(center frequency between 3 dB points)
f
C
—
Minimum insertion attenuation
α
min
(including losses in matching network)
314,84 ... 315,16 MHz
Pass band
(relative to
α
min
)
314,84 ... 315,16 MHz
314,82 ... 315,18 MHz
314,78 ... 315,22 MHz
Pass bandwidth
α
rel
≤ 3
dB
Relative attenuation
(relative to
α
min
)
10,00 ... 294,50
294,50 ... 304,50
304,50 ... 312,80
312,80 ... 313,20
313,20 ... 314,30
316,00
318,00
325,00
335,00
600,00
... 318,00
... 325,00
... 335,00
... 600,00
...1000,00
α
rel
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
—
2,1
3,0
dB
—
—
—
0,5
0,7
1,0
2,0
3,0
6,0
dB
dB
dB
0,57
0,62
0,67
MHz
53
48
33
38
9
9
15
43
48
60
58
53
38
44
12
11
19
48
53
70
—
—
—
—
—
—
—
—
—
—
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
Impedance
for pass band matching
2)
Input:
Z
IN
=
R
IN
||
C
IN
Output:
Z
OUT
=
R
OUT
||
C
OUT
2)
—
—
560 || 2,0
560 || 2,0
—
—
Ω
|| pF
Ω
|| pF
Impedance for passband matching bases on an ideal, perfect matching of the SAW filter to
source- and to load impedance (here 50 Ohm). After the SAW filter is removed and input imped-
ance into the input matching / output matching network is calculated.
The conjugate complex value of these characteristic impedances are the input and output imped-
ances for flat passband. For more details, we refer to EPCOS application note #4.
3
Mar 13, 2003
SAW Components
Low-loss Filter
Data Sheet
Matching network to 50
Ω
(element values depend on pcb layout and equivalent circuit)
C
p1
= 1,0 pF
L
s2
= 82 nH
L
s3
= 82 nH
C
p4
= 1,0 pF
B3751
315,00 MHz
Minimising the crosstalk
For a good ultimate rejection a low crosstalk is necessary. Low crosstalk can be realised with
a good RF layout. The major crosstalk mechanism is caused by the “ground-loop” problem.
Grounding loops are created if input-and output transducer GND are connected on the top-side
of the PCB and fed to the system grounding plane by a common via hole. To avoid the common
ground path, the ground pin of the input- and output transducer are fed to the system ground
plane (bottom PCB plane) by their own via hole. The transducers’ grounding pins should be
isolated from the upper grounding plane.
A common GND inductivity of 0.5nH degrades the ultimate rejection (crosstalk) by 20dB.
The optimised PCB layout, including matching network for transformation to 50 Ohm, is shown
here. In this PCB layout the grounding loops are minimised to realise good ultimate rejection.
Optimised PCB layout for SAW filters in QCC8C package, pinning 2,5 (top side, scale 1:1)
The bottom side is a copper plane (system ground area). The input and output grounding pins
are isolated and connected to the common ground by separated via holes.
For good contact of the upper grounding area with the lower side it is necessary to place
enough via holes.
4
Mar 13, 2003
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