B3574 [EPCOS]
Low Loss Filter; 低损耗滤波器SAW Components
Preliminary Data B3574 (LD25A)
SAW Components
Low Loss Filter
B3574 (LD25A)
868,30 MHz
Preliminary Data
Ceramic package QCC8C
Features
● RF low-loss filter for remote control receivers
● Package for Surface Mounted Technology
(SMT)
● Balanced and unbalanced operation possible
Terminals
● Ni, gold plated
typ. dimensions in mm, approx. weight 0,1 g
Pin configuration
1
2
5
6
7
Input
Input Ground or balanced input
Output
Output Ground or balanced output
External coupling coil
4,8
3
Case-Ground
to be grounded
Type
LD25A
Ordering code
Marking and package ac- Packing
cording too
according to
C61157–A7–A56
F61074–V8070–Z000
Electrostactic Sensitive Device (ESD)
Maximum ratings
Operable temperature range TA
Storage temperature range Tstg
– 45/+ 95
˚C
˚C
– 45/+ 95
DC voltage
VDC
PS
0
0
V
Source power
dBm
2
May 09, 2001
SAW Components
Low Loss Filter
B3574 (LD25A)
868,30 MHz
Preliminary Data
Characteristics
Reference temperature:
TA = -45 ... 95 ˚C
Terminating source impedance:
Terminating load impedance:
ZS = 50 Ω and matching network
ZL = 50 Ω and matching network
min.
typ.
max.
fC
—
868,30
—
MHz
dB
Center frequency
(center frequency between 3 dB points)
Minimum insertion attenuation
αmin
868,20 ... 868,40 MHz
(including loss in matching coils)
Amplitude ripple (p-p)
—
4,2
5,7
868,20 ... 868,40 MHz
868,16 ... 868,44 MHz
—
—
0,5
0,7
2,0
3,0
dB
dB
Relative attenuation (relative to αmin
)
αrel
10,00 ... 600,00 MHz
600,00 ... 800,00 MHz
800,00 ... 848,00 MHz
848,00 ... 863,00 MHz
863,00 ... 866,80 MHz
870,00 ... 872,00 MHz
872,00 ... 882,00 MHz
882,00 ...1000,00 MHz
60
42
54
51
37
30
47
50
65
47
59
56
42
35
52
55
—
—
—
—
—
—
—
—
dB
dB
dB
dB
dB
dB
dB
dB
Impedance for pass band matching 2)
Input: ZIN = RIN || CIN
Output: ZOUT = ROUT || COUT
—
—
360 || 1,3
380 || 1,3
—
—
Ω || pF
Ω || pF
Temperature coefficient of frequency 1)
Frequency inversion point
TCf
T0
—
-0,03
—
—
ppm/K2
10
40
°C
1)Temperature dependance of fC: fC(TA) = fC(T0) (1 + TCf(TA - T0)2)
2) 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
May 09, 2001
SAW Components
Low Loss Filter
B3574 (LD25A)
868,30 MHz
Preliminary Data
Matching network to 50 Ω (element values depend on pcb layout and equivalent circuit)
Ls1 = 18 nH
Lp2 = 39 nH
Lp3 = 39 nH
Ls4 = 18 nH
Lk = 12 nH
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 1,5 (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
May 09, 2001
SAW Components
Low Loss Filter
B3574 (LD25A)
868,30 MHz
Preliminary Data
Normalized frequency response
Normalized frequency response (wideband)
5
May 09, 2001
SAW Components
Low Loss Filter
B3574 (LD25A)
868,30 MHz
Preliminary Data
Published by EPCOS AG
Surface Acoustic Wave Components Division, SAW CE AE PD
P.O. Box 80 17 09, D-81617 München
EPCOS AG 2001. All Rights Reserved.
As far as patents or other rights of third parties are concerned, liability is only assumed for compo-
nents per se, not for applications, processes and circuits implemented within components or
assemblies.
The information describes the type of component and shall not be considered as assured
characteristics.
Terms of delivery and rights to change design reserved.
For questions on technology, prices and delivery please contact the sales offices of EPCOS AG or
the international representatives.
Due to technical requirements components may contain dangerous substances. For information on
the type in question please also contact one of our sales offices.
6
May 09, 2001
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