APPENDIX A

STLC3055 Test Circuits

Referring to the application diagram shown in fig. 7 of the STLC3055 datasheet and using as external

components the Typ. Values specified in the ”External Components” Table (page 13) find below the

proper configuration for each measurement.

All measurements requiring DC current termination should be performed using ”Wandel & Goltermann

DC Loop Holding Circuit GH-1” or equivalent.

TIP

RING

RX

TX

STLC3055

application

circuit

W&G GH1

Zref

E

Vs

1Kohm

1Kohm

100

µF

100mA

DC max

Zin = 100K

200 to 6kHz

600ohm

100

µF

Figure A1. 2W Return Loss

2WRL = 20Log(|Zref + Zs|/|Zref-Zs|) = 20Log(E/2Vs)

TIP

RING

RX

TX

STLC3055

application

circuit

W&G GH1

Vrx

Vtx

100

µF

100

µF

100mA

DC max

Zin = 100K

200 to 6kHz

600ohm

Figure A2. THL Trans Hybrid Loss

THL = 20Log|Vrx/Vtx|

STLC3055

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