Bt8370/8375/8376
2.0 Circuit Description
Fully Integrated T1/E1 Framer and Line Interface
2.2 Receive Line Interface Unit
2.2 Receive Line Interface Unit
The Receive Line Interface Unit (RLIU) recovers clock and data from the bipolar
Alternate Mark Inversion (AMI) line signal that has been attenuated and distorted
due to the characteristics of the line. In the Bt8370 device, the RLIU is sensitive
to signals attenuated in the range of 0 to –48 dB in E1 and T1 modes. In the
Bt8375 and Bt8376 devices, RLIU sensitivity is limited for short-haul only
applications. In addition, the RLIU interfaces at the DSX-1 Bridge Monitor Level
(–20 dB for DS1 and –30 dB for E1/CEPT).
The RLIU converts AMI pulses into P and N rail Non-Return to 0 (NRZ) data.
The AMI pulses are input on the receive tip and ring pins: RTIP and RRING
(Figure 2-4). The P and N rail NRZ data is then passed to the RCVR. The RCVR
dual rail output is available on RPOSO/RNEGO. Figure 2-5 illustrates the
relationship between the AMI received signal, the recovered clock, and the
RCVR dual rail outputs.
Figure 2-4. RLIU Diagram
RDIGI
RJAT
RPOSI
RNEGI
1
O
RTIP
O
Adaptive
Equalizer
Data
Slicer
RRING
RPOSO
RNEGO
O
VGA
ADC
1
1
ALOOP
RPLL
ADC
1
RXCLK
O
RCKI
To JAT
Analog Loopback
From JAT
N8370DSE
Conexant
2-5
CONEXANT [ CONEXANT SYSTEMS, INC ]
