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S5N8951X

G.dmt ADSL Analog Front End IC

CONFIDENTIAL

Preliminary Information (Rev.1.0)

3. BLOCK DESCRIPTIONS

3.1 ADC / DAC

S5N8951X01 has a 14bit resolution ADC 4.416M/8.832M sample frequency.

The input of ADC is fully differential 2.0Vppd Max. The ADC transforms the

signal into a digital 14bit output.

There are two type of DAC’ s in S5N8951X01. One is for TX. It is 14bit

4.416MHz/8.832MHz frequency. Samsung’ s DMT(S5N8950) transmit 14bit

parallel data to the AFE chip. The other DAC is for VCXO control. It has 10bit

resolution 4KHz frequency. Internal registers of S5N8951X01 transform 10bit

VCXO control serial data from DSP into 10bit parallel data. And VCXO output

analog signal CONT_DAX(Pin #40).

3.2 TX/RX LPF

3.2.1 RX FILTERS

The combination of the external filter ( an LC ladder filter typically ) with the

integrated low pass filter must provide:

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DMT sidelobe and out of band ( anti-aliasing ) attenuation

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Anti alias filter ( 60dB rejection @ image frequency )

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On chip tuning circuit included.

3.2.2 TX FILTERS

The TX Filters act not only to suppress the DMT sidebands but also as

smoothing filters on the D/A converter’ s output to suppress the image spectrum.

For this reason they are realized in a time continuous approach and on chip

tuning circuit included

3.3 TX/RX AGC

TX AGC has 0~-24dB gains with 2dB step. It is controlled through 8bit serial

digital signal from DSP. Internal registers of Samsung AFE Chips transform

8bit parallel control data. It outputs 2Vppd fully differential signal to line driver.

RX AGC has low noise 0~42dB gains with 0.4dB step and It is controlled

through 12bit + 1MSB control signal. If 1MSB is high, another RX input pass

pin#55 RX_INNG #56 RX_INNP(external -14dB gain pass) is seclected. It inputs

2Vppd fully differential signal to RX LPF.