Ltp: tft029
version 1.2
04.06.03
VI
TELEFILTER
Application Note
TFS 210G
1/2
1. General
The filter is single ended driven. It is matched to 50
Ω.
The matching element values given below are valid on the test PCB. If the parasitics on the
customer PCB and on this PCB are different, the matching elements have to be optimised
regarding the circuit and PCB design.
The matching elements have been chosen from the E12- series (European standard series
with fixed tolerances).
2. Theoretical matching
The termination impedances of the filter are:
source impedance:
860
Ω
|| - 6,4 pF
load impedance:
1160
Ω
|| - 6,7 pF
The values of the matching elements which are given below are calculated from the source
and load impedance. If the values of the matching elements are not equal to standard values
the best standard values are given in brackets.
50
Ω
test circuit
L1 1
Input
50 Ohm
C1
6
L2
Output
50 Ohm
C2
SAW
2,3,4,5,7,8,9,10
L1 = 100,8 nH
L2 = 96,4 nH
C1 =
30 pF
C2 = 33,8 pF
TELEFILTER GmbH
Potsdamer Straße 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail:
tft@telefilter.com
VI TELEFILTER reserves the right to make changes to the product(s) and/or information contained herein without notice. No liability is
assumed as a result of their use or application. No rights under any patent accompany the sale of any such product(s) or information.
Ltp: tft029
version 1.2
04.06.03
VI
TELEFILTER
Application Note
TFS 210G
2/2
3. Matching on the PCB
For example: PCB with 50
Ω
test circuit
L1 1
Input
50 Ohm
C1
C3
2,3,4,5,7,8,9,10
6
L2
Output
50 Ohm
SAW
C2
L1 = 82 nH
L2 = 56 nH
C1 = 33 pF
All other components are 0
Ω
jumpers.
C2 = 39 pF
C3 = 1,2 pF
The matching on the PCB does slightly differ from the theoretical matching. The reason for
that are parasitics of the PCB.
If the parasitics on the customer board (mentioned parasitics, additional parasitics of active
parts) are different to this PCB the matching elements have to be slightly adjusted.
In case of questions please contact us to
TELEFILTER GmbH
Potsdamer Straße 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail:
tft@telefilter.com
VI TELEFILTER reserves the right to make changes to the product(s) and/or information contained herein without notice. No liability is
assumed as a result of their use or application. No rights under any patent accompany the sale of any such product(s) or information.