Ltp:tft031
version 1.0
18.12.08
______________________________________________________________________________________________________
VI
TELEFILTER
1. General
Application Note
TFS 210C -
1/2
______________________________________________________________________________________________________
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:
295
Ω
|| 1,15 pF
load impedance:
295
Ω
|| 1,15 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 1
L1
7
1
L2
C1
SAW
C2
2,3,4,5,6,8,9,10,11,12
L1 = 84 nH
C1 = 6.8 pF
50
Ω
test circuit 2
C1
7
L2 = 84 nH
C2 = 6.8 pF
1
C2
L1
SAW
L2
2,3,4,5,6,8,9,10,11,12
C1 = 6.8 pF
L1 =126 nH
C2 = 6.8 pF
L2 =126 nH
VI TELEFILTER
Potsdamer Straße 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail: tft@telefilter.com
Vectron International, Inc.
267 Lowell Road
Hudson, NH 03051 / USA
Tel: (603) 598-0070 Fax: (603) 598-0075
E-Mail: vti@vtinh.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:tft031
version 1.0
18.12.08
______________________________________________________________________________________________________
VI
TELEFILTER
Application Note
TFS 210C -
2/2
______________________________________________________________________________________________________
3. Matching on the PCB
For example: PCB with 50
Ω
test circuit 1
L1
7
1
L2
C1
SAW
C2
2,3,4,5,6,8,9,10,11,12
L1 = 68 nH
C1 = 4.7 pF
L2 = 68 nH
C2 = 4.7 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
VI TELEFILTER
Potsdamer Straße 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail: tft@telefilter.com
Vectron International, Inc.
267 Lowell Road
Hudson, NH 03051 / USA
Tel: (603) 598-0070 Fax: (603) 598-0075
E-Mail: vti@vtinh.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.
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