TFS321_0106 Datasheet, PDF (1/3 Pages) Vectron International, Inc – Application Note

Ltp: tft025
VI TELEFILTER
1. General
version 1.0
Application Note
TFS 321
19.06.2001
1/3
The filter is symmetrical, i.e. input and output are exchangeable with each other. But the
external coupling coil has to be connected to pin 3 in any case.
The filter can be driven both, balanced and unbalanced. The current specification is valid only
for unbalanced use. Please contact us if the filter shall be used balanced at one or both ports.
The termination impedances are : 480 Ω || -1.6 pF
This impedance is equal for the input and the output. It has to be realized at the point were the
filter is mounted. To match this impedance to the impedance of the system a matching circuit
is required.
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
For the matching of termination impedances to 50 Ohm there can be used two different
matching circuits
50 Ohm Test circuit 1
L1
5
1
L2
C1
SAW
C2
3
2, 4, 6, 7, 8
L3
The theoretical values of the stated elements are:
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