
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.
1. General
The filter is unbalanced driven. It is matched to 50
The matching element values given below are valid on the test PCB. If the parasitic on the customer
PCB and on this PCB are different, the matching elements have to be optimized regarding the circuit
and PCB design.
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 unbalanced driven terminating impedances of the filter are:
Input impedance:
218
|| 0.6 pF
Output impedance:
168
|| 0.07 pF
The values of the matching elements which are given below are calculated from the input and output
impedance. If the values of the matching elements are not equal to standard values the best standard
values are given in brackets.
L1
staed
L1 = 29 nH
L2 = 27 nH
The calculation was made without consideration of parasitics. The elements which have to be used on
the PCB are slightly different from the stated due to these parasitics (see matching on PCB)
SAW
1,2,5,6,7
8,11,12
3
9
L2
Input
50 Ohm
C2
Input
50 Ohm
C1
C1 = 1,9 pF
C2 = 2,55 pF
VI
TELEFILTER
________________________________________________________ version 1.0
______________________________ Oct /
11 / 00 _____
Application Note
TFS 326 - 1 / 2
__________________________________________________________________________________
VI TELEFILTER
Potsdamer Strae 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail: tft@telefilter.com
Vectron Technologies, Inc.
267 Lowell Road
Hudson, NH 03051 / USA
Tel: (603) 598-0070 Fax: (603) 598-0075
E-Mail: vti@vtinh.com