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Achieving Low Power and High Speed in Paging System
IF IC for High-Speed Paging Systems
CXA3117N, CXA3176N, CXA3179N
High-speed paging systems that employ M-ary signals are about to
enter service.
Sony strongly supports this new service with three IF ICs: the
CXA3117N, the CXA3176N, and the CXA3179N.
The CXA3117N, which adopts a comparator system that does not re-
quire an A/D converter, and the CXA3179N, which supports AFC, can
contribute significantly to parts count reductions and thus reduced pro-
duction costs.
The CXA3176N implements a high-speed paging system that uses an
A/D converter and supports AFC.
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Low current consumption
( C X A 3 1 1 7 N / C X A 3 1 7 6 N /
CXA3179N)
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No A/D converter required in
comparator system adopted
(CXA3117N/CXA3179N)
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AFC support (CXA3176N/
CXA3179N)
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RSSI dynamic range: 70 dB,
detector output: 600 mVrms
(CXA3176N)
Low Current Consumption
At the same time as incorporating both
a comparator that supports M-ary high-
speed paging systems and a variable cut-
off bit rate filter that responds to
changes in the data rate, these products
achieve a current consumption that is
20% lower than that of the POCSAG
system based CXA1484AN.
Comparator System
does not Require an A/D
Converter
In the first generation of M-ary high-
speed paging systems, the output of the
detector was input to an A/D
converter to acquire the two bits of data
in the signal. However, the comparator-
based system used in these products
uses three comparators to perform a
signal-processing operation equivalent
to A/D conversion and acquire the two
bits of digital data. This allows circuits
that were previously implemented as
two chips, an IF IC and an A/D
converter, to be implemented in a single
IF IC.
AFC Support
A circuit that cancels the frequency off-
set of the receiver oscillator is required
in 900-MHz band paging systems and
in narrow band systems. The
CXA3176N and CXA3179N include an
offset detection circuit that uses S-curve
characteristics, and implement an AFC
circuit by feeding back the output of this
circuit to the first oscillator.
I am convinced that the compara-
tor system proposed by Sony and
used in the CXA3117N and
CXA3179N will become the main-
stream in M-ary paging systems in
the future. I think that once you
have tried these devices you will
appreciate the validity of this
system. Please look into these
products for use in your systems.
RSSI Dynamic Range: 70 dB,
Detector Output: 600 mVrms
In addition to providing the extremely
wide RSSI dynamic range of 70 dB, the
CXA3176N also features excellent tem-
perature characteristics. These allow the
CXA3176N to be used in a wide range
of applications. Furthermore, the
CXA3176N detector output operating
point is automatically adjusted to
achieve an optimal dynamic range in
response to the supply voltage.
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Figure 1 High-Speed Paging System
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Figure 2 High-Speed Paging IF Amplifiers
system
Product name
1.1 to 4.0
1.1
IF amplifier in M-ary FSK pagers
Regulator output for use by the front-end circuit
Built-in second mixer
RSSI function defecting the weak signal level
Dynamic range: 45 dB (typ.)
Misoperation prevention function for
continuous data
Bit rate filter switching
Level comparator output
Regulator output for use by the front-end circuit
Built-in second mixer
RSSI function defecting the weak signal level
Dynamic range: 70 dB (typ.)
AFC function
Standard audio output level: about 600 mVrms
CXA3117N
Double conversion
V
CC
1: 1.1 to 4.0 V
CC
2: 2.5 to 4.0
V
CC
1: 0.95 V
CC
2: 0.2
24-pin SSOP
CXA3176N
IF amplifier in AFC supported FM
receivers
Regulator output for use by the front-end circuit
Built-in second mixer
RSSI function defecting the weak signal level
Dynamic range: 45 dB (typ.)
AFC function
Bit rate filter switching
Level comparator output
1.1 to 4.0
1.1
CXA3179N
IF amplifier in 900-MHz band and
narrow band M-ary FSK pagers
Package
Current consumption (mA)
Operating supply voltage
(V)
Features
Applications
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Table 1
Lineup for High-Speed Paging System Supported IC
Faster Operation
M-ary Data
High Frequency
Narrow Band
Support for M-ary FSK
Bit Rate Filter
AFC Support
FLEX
FLEX-TD
Level Comparator Output
CXA3117N
900MHz Band
Narrow Band
Level Comparator Output
CXA3179N
AFC Supported
FM Receiver
Audio Output
CXA3176N
ADC Support
Ceramic
Filter
IF = 21.7MHz
Data Rate 6400/4
RF Amp.
BPF1
BPF2
LPF
MIX1
IF Amp.
CXA3117N
OSC1
MIX2
OSC2
RSSI
LVA
DET
LIM
Ceramic
Resonator
LCD
Driver
FLEX
Decoder
Decoder
Level
COMP
Bit Rate
Filter SW
ROM
RAM
LCD
Driver
LED
Vibrator
Speaker
System
Controller
M
455kHz
NRZ
COMP
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