MTC20154

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TX Pre-driver Capability

The pre-driver drives an external line power amplifier which transmits the required power to the line.

Table 15. Pre-driver characteristics

TX Filter

The TX filters act not only to suppress the DMT sidebands but also as smoothing filters on the D/A con-

verter’s output to suppress the image spectrum. For this reason they are realised in a time continuous ap-

proach.

ATU-R-TX Filter

The purpose of this filter is to remove out-of-band noise of the ATU-R-TX path echoed to the ATU-R-RX

path. In order to meet the transmitter spectral response, additional filtering is (digitally) performed. The

integrated filter has nominal characteristics shown in table 11:

Table 16. ATU-R-TX filter characteristics

ATU-C-TX Filter

Same filter as ATU-R-RX. Its purpose is now is to remove image frequency of the transmitted signal ac-

cording the ANSI definition.

Table 17. D/A Converter

TX drive level to the external line driver for max AGC setting

2 Vpdif

External line driver input impedance:

resistive

> 200

Ω

capacitive

< 30 pF

Pre-driver characteristics:

gain range:

-9 dB...6 dB with step = 1 dB

common mode voltage:

AVDB/2

output common mode voltage:

30 nV/Hz

Description

Value/Units

Input refered noise

94 nV/

Max. input level

1 Vpd

Max. output level

1 Vpd

Type

4th order chebychef

Cut-off frequency

138 KHz (f0)

Max. in-band ripple

0.5 dB

Description

Value/Units

Number of bits:

12 bits

Minimum resolution of the D/A converter

11 bits

Linearity error of the D/A converter

< 1 LSB (out of 12 bits)

Full scale output range:

1 Vpdif +- 5%

Sampling Rate:

8.832 MHz (or 4.416 in alternative mode)

Latency:

1 sampling clock period

Hz