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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 require an A/D converter, and the CXA3179N, which supports AFC, can contribute significantly to parts count reductions and thus reduced production 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 (CXA3117N/CXA3176N/ CXA3179N) No A/D converter required in comparator system adopted (CXA3117N/CXA3179N) AFC support (CXA3176N/ CXA3179N) 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 highspeed paging systems and a variable cutoff 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 highspeed 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 comparatorbased 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.
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 temperature 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.
AFC Support
A circuit that cancels the frequency offset 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.
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I am convinced that the comparator system proposed by Sony and used in the CXA3117N and CXA3179N will become the mainstream 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.
Ceramic Filter
Ceramic Resonator
ROM
RF Amp. BPF1 MIX1 BPF2
MIX2 LIM
455kHz
LPF NRZ COMP DET RSSI FLEX Decoder System Controller RAM Driver M Speaker LED Vibrator LCD Driver LCD
OSC1
OSC2
Level COMP IF = 21.7MHz Data Rate 6400/4 LVA Bit Rate Filter SW IF Amp.
CXA3117N
Decoder
s Figure 1 High-Speed Paging System
* Support for M-ary FSK * Bit Rate Filter
* AFC Support Level Comparator Output
Level Comparator Output
CXA3117N
* Faster Operation * M-ary Data * FLEX * FLEX-TD
que d Fre igh w Ban * H rro a *N
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CXA3179N
* 900MHz Band * Narrow Band
ADC
Sup
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Audio Output
CXA3176N
* AFC Supported FM Receiver
s Figure 2 High-Speed Paging IF Amplifiers s Table 1
system Operating supply voltage (V) Current consumption (mA) Package * 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 IF amplifier in M-ary FSK pagers 1.1 to 4.0 1.1
Lineup for High-Speed Paging System Supported IC
CXA3117N CXA3176N Double conversion VCC1: 1.1 to 4.0 VCC2: 2.5 to 4.0 VCC1: 0.95 VCC2: 0.2 24-pin SSOP * 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 * 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 IF amplifier in 900-MHz band and narrow band M-ary FSK pagers 1.1 to 4.0 1.1 CXA3179N
Product name
Features
Applications
IF amplifier in AFC supported FM receivers

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