
Ltp: tft025
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VI TELEFILTER
Application Note
______________________________________________________________________________________________________
1. General
The filter is balanced driven. It is matched to 50
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.
There are ground pin thru’s under the filter and in the other area of the PCB but additional pin thru’s to
decrease cross talk.
The matching elements have been chosen from the E12- series (European standard series with fixed
tolerances) to get the best agreement between the PCB measurement and the measurement in a
reference test fixture.
2. Theoretical matching
The balanced driven source and load impedances of the filter are:
Source impedance:
360
|| - 1.05 pF
Load impedance:
360
|| - 1.05 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
Test circuit 1
5
LB-IN
version 1.2
25.09.2000
TFS360A
1/3
VI TELEFILTER
Potsdamer Strae 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-52 / 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.
Vectron International, Inc.
267 Lowell Road
Hudson, NH 03051 / USA
Phone: (603) 598-0070 Fax: (603) 598-0075
e-mail: vti@vtinh.com
2
1
6
4,7,8
LB-OUT
SAW
C1
L1
C2
L4
L2
L5
L3
3
L1 = L2 = L3 = L4 = 27.5 nH
C1 = C2 = 2 pF
L5 = 91 nH