U4092B

TELEFUNKEN Semiconductors

Preliminary Information

11

Rev. A1: 24.01.1995

–

GT

MICO

TIN

INLDT

TLDT

VBG

–

+

STO

VL

Zint

TXA

AFS

control

AGA

Max

att.

VBG

+

TLDR

RECO

GR

STI

STN

STO

SAI

SAI

GSA

SAO

Z

L

RECIN

95 9629

INLDR

VL

Figure 9 Integration of acoustic feedback suppression circuit into the speech circuit environment

A detailed diagram of the AFS (acountic feedback

suppression) is given in figure 10. Receive and Transmit

signals are first processed by logorithmic rectifiers in order

to produce the envelopes of the speech at TLDT and RLDT.

After amplification a decision is made by the differential

pair, which direction should be transmitted.