P3357
MATCHING RECOMMENDATIONS
The following recommendations start with the simplest implementations and progress to enhanced
performance utilizing additional components.
Good performance is achieved even with the simplest
configurations. The implementations assume a low impedance balanced TX drive and a relatively high
impedance RX input, as is commonly available, though use with other TX/RX arrangements is
straightforward. Note that there are no changes to components on the line side, or in the hybrid, whether
600Ω or complex reference impedance selected, thus assisting country configuration. For complex
impedance, the matching circuits derived are suitable for reference impedances of the type 270 + 750//150nF
e.g. European CTR21 and 220 + 820//120nF (or 115nF) e.g. Australia, South Africa, etc., and yield similar
performance characteristics. For other impedances, please contact Profec Technologies.
Minimum Cost Implementations
600Ω
Fig. 2
600
22
μ
F
560
European CT
R21/(Australia, etc.)
F 3
ig.
270
(220)
150nF
(120nF)
22
μ
F
100
100nF*
T
XA1
LINE
R
XA
T
XA2
750
(820)
820
T
XA1
R
XA
T
XA2
LINE
* Note: 100nF capacitor should have a temperature stable dielec tric
Insertion Loss: 1.8dB @ 2kHz
Frequency Response : ±0.2dB 30Hz – 10kHz
Return Loss: 16dB 200Hz – 4kHz
Transhybrid Loss: 22dB 200Hz – 4kHz
Improved matching
Insertion Loss: 1.0dB @ 2kHz
Frequency Response : ±0.5dB 50Hz – 4kHz
Return Loss: 18dB 200Hz – 4kHz
Transhybrid Loss: 14dB 200Hz – 4kHz
600Ω
Fig. 4
600
22
μ
F
560
European CT
R21/(Australia, etc.)
F 5
ig.
270
(220)
150nF
(120nF)
22
μ
F
100nF*
120
T
XA1
LINE
10nF
T
XA1
750
(820)
750
10nF
R
XA
T
XA2
R
XA
T
XA2
LINE
* Note: 100nF capacitor should have a temperature stable dielec tric
Insertion Loss: 1.8dB @ 2kHz
Frequency Response : ±0.2dB 30Hz – 10kHz
Return Loss: 18dB 200Hz – 4kHz
Transhybrid Loss: 22dB 50Hz – 10kHz
Insertion Loss: 1.0dB @ 2kHz
Frequency Response : ±0.5dB 50Hz – 4kHz
Return Loss: 20dB 200Hz – 4kHz
Transhybrid Loss: 16dB 50Hz – 4kHz
Patented
ETALDOC 724/7
Page 3 of 5
April 2005
ETAL [ ETAL Group ]
