PSB4596 Siemens Semiconductor Group, PSB4596 Datasheet - Page 20

• Manufacturer Part Number: PSB4596
• Description: Analog Line Interface Solution ALIS
• Manufacturer: Siemens Semiconductor Group

4
The ALIS chip set replaces all the major parts of a conventional front end for modem
solutions. The circuit consists of two major parts, a DSP-based codec and an electronic
DAA. Advanced features such as ring detection, pulse dialing and caller ID are
integrated on-chip. Additional operating modes such as sleep mode or ringing mode are
implemented to minimize power consumption.
4.1
The tip/ring telephone line interface is connected mainly with the ALIS-A. It is also
connected with the ALIS-D for Caller ID functions..
Figure 9 ALIS Block Diagram
The analog front end (ALIS-A) is connected to the line via TIP/RING. The programmable
supply voltage for ALIS-A is generated from the line by the Vdd control. Two/four wire
conversion is implemented in the hybrid circuit. Analog anti-aliasing pre-filters (PREFI)
and smoothing post-filters (POFI) are included for signal conditioning. High-performance
over-sampling analog-to-digital converters (ADCs) and digital-to-analog converters
(DACs) assure the required conversion accuracy. The ADCs and DACs are connected
to the digital signal processor (DSP) on the digital part (ALIS-D) via a dedicated capacitor
interface which also provides the required isolation to the line. Special hardware filters
perform filtering functions such as interpolation and decimation. The DSP handles all the
necessary algorithms. These include bandpass filtering, sample rate conversion, ringing
detection, and caller ID decoding. All programmable filters and functions are also
controlled and processed by the DSP. The control interface allows external control of the
ALIS features and provides transparent access to ALIS commands and signaling pins.
Thus pre-calculated sets of coefficients can be downloaded from the system to the on-
Semiconductor Group
ALIS Implementation
ALIS Block Diagram
Transmit/Receive Data
ALIS-D
Control Interface
Data Interface
Control Data
DSP
HW-
Filter
Caller ID
Cap. Interface
Isolation
20
Analog Line Interface Solution
A/D
D/A
ALIS-A
Control
Hybrid
Filters
Vdd
and
I/O
PSB 4595 / PSB 4596
ALIS Implementation
Control
TIP/RING
Data Sheet 06.98