Document
SAW Components
SAW filter
Short range devices
Series/type: Ordering code:
Date: Version:
B3942 B39171B3942U310
April 24, 2013 2.2
EPCOS AG 2015. Reproduction, publication and dissemination of this publication, enclosures hereto and the information contained therein without EPCOS' prior express consent is prohibited.
EPCOS AG is a TDK Group Company.
SAW Components SAW filter Data sheet
Application s Low-loss RF filter for smart metering s Balanced and unbalanced operation possible
B3942 169.5 MHz
Features
s Package size 5.0 x 5.0 x 1.35 mm3 s Package code QCC8C s RoHS compatible s Approximate weight 0.1 g s Package for Surface Mount Technology (SMT) s Ni, gold-plated terminals s Lead free soldering compatible with J - STD20C s Passivation layer Elpas s AEC-Q200 qualified component family s Electrostatic Sensitive Device (ESD)
Pin configuration1)
s1 s2 s5 s6 s 4,8 s 3,7
Input (recommended) or input ground Input ground (recommended) or input Output (recommended) or output ground Output ground (recommended) or output Ground (case) to be grounded
1) The recommended pin configuration usually offers best suppression of electrical crosstalk. The filter characteristics refer to this configuration.
Please read cautions and warnings and important notes at the end of this document.
2 April 24, 2013
SAW Components SAW filter Data sheet
Characteristics
Temperature range for specification: Terminating source impedance: Terminating load impedance:
B3942 169.5 MHz
T = –40 ˚C to +85 ˚C ZS = 50 Ω and matching network ZL = 50 Ω and matching network
Center frequency
min. typ. max. @ 25 ˚C
fC — 169.5 — MHz
Minimum insertion attenuation
αmin
incl. loss in matching elements (QL = 28)
— 1.9 3.0 dB
excl. loss in matching elements
— 1.3 2.4 dB
Pass band (relative to αmin) 169.40 ... 169.60 MHz
— 0.6 1.8 dB
Relative attenuation (relative to αmin) αrel 10.00 ... 155.00 MHz
155.00 ... 168.70 MHz 171.40 ... 171.80 MHz 171.80 ... 172.80 MHz 172.80 ... 185.00 MHz 185.00 ... 300.00 MHz 871.65 ... 880.00 MHz Impedance for pass band matching1) Input: ZIN = RIN || CIN Output: ZOUT = ROUT || COUT
50 58 — dB 22 28 — dB 16 22 — dB 7 11 — dB 16 22 — dB 44 50 — dB 23 27 — dB
— 670 || 3.6 — Ω || pF — 670 || 3.6 — Ω || pF
1) Impedance for passband matching bases on an ideal, perfect matching of the SAW filter to source- and to load impedance (here 50 Ohm). After removal of the SAW filter the input impedance of the input and output matching network is calculated. The conjugate complex value of these characteristic impedances are the input and output impedances for flat passband. For more details we refer to EPCOS application note #18.
Please read cautions and warnings and important notes at the end of this document.
3 April 24, 2013
SAW Components SAW filter Data sheet
B3942 169.5 MHz
Maximum ratings
Operable temperature range T
Storage temperature range DC voltage Source power
Tstg VDC PS
–45/+125 ˚C –45/+125 ˚C
6V 10 dBm
source impedance 50 Ω
Please read cautions and warnings and important notes at the end of this document.
4 April 24, 2013
SAW Components
B3942
SAW filter
169.5 MHz
Data sheet
Matching network to 50 Ω (element values depend on pcb layout and equivalent circuit)
Cp1 = 2.2 pF Ls2 = 180 nH Ls3 = 180 nH Cp4 = 2.2 pF
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.
Please read cautions and warnings and important notes at the end of this document.
5 April 24, 2013
SAW Components SAW filter
B3942 169.5 MHz
Data sheet
ESD protection of SAW filters
SAW filters are Electro Static Discharge sensitive devices. To reduce the probability of damages
caused by ESD, special matching topologies have to be applied.
In general, “ESD matching” has to be ensured at that filter port, where electrostatic discharge is
ex.