
Ltp: tft035
VI
TELEFILTER
1. General
The filter is driven single ended. 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.
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: 630
|| -9.2 pF
Load impedance: 915
|| -.5,7 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.
2.1.
Single ended matching
L1
10
version 1.0
8.8.2000
Application Note
TFS 210E - 1/2
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
Tel: (603) 598-0070 Fax: (603) 598-0075
E-Mail: vti@vtinh.com
C2
Output
50 Ohm
L2
Input
50 Ohm
C1
SAW
1,2,3,5,6,7,
4
8,9,11,12
L1 = 77 nH (82nH)
C1 = 29 pF (27pF)
2.2.
Ballanced matching
LB-IN
L2 = 117 nH (120nH)
C2 = 19 pF (18pF)
3
4
10
9
1,2,5,6,7,8,11,12
LB-OUT
C1
L1
C2
L4
L3
L2
Input
50 Ohm
Output
50 Ohm
SAW
L1=38 nH (39 nH)
L2=38 nH (39 nH)
C1=27 pF
L3=58 nH (56 nH)
L4=58 nH (56 nH)
C2=18 pF