P3357

ETALDOC 724/7

Page 3 of 5

April 2005

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

600

Ω 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

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: 1.8dB @ 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: 18dB 200Hz – 4kHz

Transhybrid Loss: 14dB 200Hz – 4kHz

Insertion Loss: 1.0dB @ 2kHz

Frequency Response : ±0.5dB 50Hz – 4kHz

Return Loss: 20dB 200Hz – 4kHz

Transhybrid Loss: 16dB 50Hz – 4kHz

600Ω

Fig . 4

LINE

600

10nF

560

RXA

TXA2

TXA1

μ

22 F

600Ω

Fig . 2

LINE

600

560

RXA

TXA2

TXA1

μ

22 F

10nF

LINE

270

(220)

750

(820)

μ

22 F

150nF

(120nF)

750

100nF*

* Note: 100nF c a pac itor should have a tempera ture stable dielec tric

120

European CTR21/(Australia, etc.)

Fig. 5

RXA

TXA2

TXA1

LINE

270

(220)

750

(820)

150nF

(120nF)

820

100nF*

* Note: 100nF c a pac itor should have a tempera ture stable dielec tric

100

European CTR21/(Australia, etc.)

Fig. 3

RXA

TXA2

TXA1

μ

22 F

Patented