THS7102

ADSL (POTS) CENTRAL OFFICE LINE INTERFACE DRIVER/RECEIVER

SLOS311B− MAY 2000 − REVISED DECEMBER 2001

3

POST OFFICE BOX 655303

functional block diagram

BPF

LPF

_

+

Tx In

1.5 k

Ω

11.2 k

Ω

1.5 k

Ω

11.2 k

Ω

Tx Out

_

+

Rx P-In

_

+

Rx M-In

Rx Out

Buffer 2

Buffer 1

R

R

VCCL

GND

TXEN1

TXEN2

VCCL

VCCOP1

VCCOP2

TXAS2

TXAS1

TXAF

TXBF

TXBS1

TXBS2

RXPO

RXPI

RXPN

RXMO

RXMI

RXMN

2BUFIN

2BUFOUT

GND

VCCON

VAG

BUFEN

TXINP

TXINN

TXCM

RXOUTP

RXOUTN

RXCM

1BUFIN

1BUFOUT

_

+

X1

_

+

10.2 k

Ω

The THS7102 is designed to implement full-rate ADSL signals over the same line as POTS signals at the central

office (CO). The THS7102 transmit BPF consists of a low-pass filter and a high-pass filter. The low-pass filter

portion of the BPF is comprised of a third order Chebyshev filter with a 0.33-dB passband ripple and a breakpoint

frequency of 1.3 MHz. The high-pass portion of the BPF is a 0.33-dB passband ripple Chebyshev with a

breakpoint frequency at 151.7 kHz. This high-pass section requires that a 680-pF capacitor be used at each

transmit input (TXINP and TXINN) for the appropriate Chebyshev response. Together the LPF and HPF form

a bandpass filter with a passband ripple of about 0.6 dB. The THS7102 receive LPF is comprised of a fourth

order Chebyshev filter with a 0.25-dB passband ripple and a breakpoint frequency of 146 kHz.

NOTE:

The definition of breakpoint frequency is the frequency at which the attenuation leaves the ripple band.