CML Semiconductor Products
Cordless Telephone Scrambler
D/128/1 October 1997
FX128
Provisional Information
Features
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Full-Duplex Audio Processing
On-Chip Filters
Carrier Rejection >55dB
Uses IF (10.24MHz) Clock
Requires No Extra Crystal
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Excellent Audio Quality
Low Power Operation (3.0V)
ECPA* Qualified Voice Protection
Battery Powered Portability
Cordless Telephones and Wireless PBX
Applications
1.1
Brief Description
The FX128 is a full-duplex frequency inversion scrambler designed to provide secure conversations for
46/49 MHz cordless telephone users. The Rx and Tx audio paths consist of the following:
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A switched-capacitor balanced modulator with high baseband and carrier rejection.
A 3.3kHz inversion carrier (injection tone).
A 3100Hz lowpass filter.
Input op-amps with externally adjustable gain.
The FX128 uses mixed signal CMOS switched-capacitor filter technology and operates from a single supply in
the range of 3.0 to 5.5 volts. The inversion carrier's frequency and filter switching clock are generated on-chip
using an external 10.24MHz or 3.58/3.6864 MHz crystal or clock input (selectable).
This device is available in 16-pin SOIC (FX128D4) and 16-pin plastic DIL (FX128P3) packages.
*Electronics Communications Privacy Act (Title 18, US Code 2510 etc.).
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