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MTC20154

ATU-C Side Block Diagram

The transformer at the ATU-C side has a 1:2 ratio. The termination resistors are 12.5

Ω in case of 100Ω

lines. The hybrid bridge resistors should be < 2.5 k

Ω for low-noise.

An HP filter must be used on the TX path to reduce DMT sidelobes and out-of-band noise influence on the

receiver.

On the RX path, a LP filter must be used in order to reduce the echo signal level and to avoid saturation

of the input stage of the receiver.

The POTS filter is used in both directions to reduce crosstalk between ADSL signals and POTS speech

and signalling.

Figure 4. ATU-C AFE Schematics (For detailed schematics see MTB-20150-EBC reference design.)

Gtx

line driver

Pots Filter

LP

Pots Filter

POTS

H

P

F

TXP

TXN

RXT1

RXT2

P.D.

-g..+6db

-15.. 31db

LP 1.1 MHz

LP 138 KHz

MTC-20154

VCODAC

VCXO

35.328 MHz or 17.664 MHz

LNA

D/A

convertor

D/A

convertor

12bits

8.832 MS/s

4.416 MS/s

4

RESETN

LTNT=1

CTRLIN

4

13bits

8.832 MS/s

4.416 MS/s

Master clock 35.328 MHz

Nibbles 17.664 MHz

Word 8.832/4.416 MHz

L

P

F

RXN [0:1]

RXP [0:1]