PSB2163T-V31TR Infineon Technologies, PSB2163T-V31TR Datasheet - Page 130

• Manufacturer Part Number: PSB2163T-V31TR
• Description: IC AUDIO RINGING CODEC 28-PDSO
• Manufacturer: Infineon Technologies
• Series: ARCOFI®r

Specifications of PSB2163T-V31TR

• Function: CODEC Filter
• Interface: IOM-2, PCI, Serial
• Number Of Circuits: 1
• Voltage - Supply: 5V
• Current - Supply: 900µA
• Power (watts): 1mW
• Operating Temperature: -25°C ~ 80°C
• Mounting Type: Surface Mount
• Package / Case: DSO-28
• Includes: Activation and Deactivation, B-Channel and D-Channel HDLC Controllers, D-Channel Priority Handler, Monitor Channel Handler
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Other names: PSB2163T-V31INTR; PSB2163T-V31TR

1
1.1
Plain telephony suffers from the fact of being tied to a telephone set, and even mobile
telephony requires at least a handset to be held. To move freely for e.g. fetching some
documents needed during a discussion or when phoning while driving a car, the
speakerphone support is an important feature of telephone terminals.
High-feature telephones are mainly to be found as terminal devices in private exchanges
(PABX) and central offices (CO) to offer enhanced comfort compared to plain analog
terminals. In an Integrated Services Digital Network (ISDN), which opens access to a lot
of completely new services in the large list of terminal features, the speakerphone
support ranges on top and may be considered as a standard feature of comfort
terminals. But even high quality analog terminals take more and more advantage of
digital signal processing techniques and offer speakerphone support.
In contrast to using a handset which by its construction precludes feedback from
loudspeaker to microphone, the speakerphone feature opens such bypasses. It involves
much technical expense to cope with these various and time-varying couplings at a
reasonable performance level.
In general, today´s speakerphone realizations are based on a half-duplex transmission
mode which breaks the existing acoustic coupling between the receiver loudspeaker and
the speakerphone microphone by amplifying just one path (receive or transmit) while the
other one is attenuated.
Former realizations required a lot of discrete components to achieve a satisfying quality,
where "satisfying" is still subject to a rather personal sensation. Contemporary solutions
consist of an integrated circuit with still about 40 passive external components instead.
They reach an acceptable quality, but optimization is mainly empirical and tuning the
circuitry to the particular preferences of the user is impossible.
Controlled loudhearing, also called monitoring, is a valuable and very comfortable
feature, since it allows other people to follow a discussion running with a remote phone
partner. With the ARCOFI-SP, loudhearing can be regarded as a particular
speakerphone mode with reduced attenuation while using the handset microphone.
The digital realization of the speakerphone feature greatly simplifies the optimization and
tuning procedure by using the efficiency of a digital signal processor. The ARCOFI-SP
PSB 2163 incorporates the necessary computing capacity to realize a speakerphone of
superior performance without any external components. In the following sections the
typical coupling problems and technical solutions will be discussed, before in the second
part of this application note the concrete realization with the PSB 2163 is described in
detail.
Semiconductor Group
General Aspects of Speakerphone Realizations
Introduction
129
Speakerphone Implementation