MX118P

MX118 FULL-DUPLEX SCRAMBLER FOR CORDLESS TELEPHONES Features Full-Duplex Audio Processing On-Chip “Brick-wall” Filters (300-3000 Hz) Low Voltage CMOS High Baseband and Carrier Rejection Excellent Audio Quality ECPA* Qualified Voice Protection Applications Cordless Telephones & Wireless PBXs Battery Powered Portability MX118P (16 pin PDIP) MX118DW (SOIC-16) Description The MX118 is a full-duplex frequency inversion scrambler that secures cordless telephone conversations. The two audio paths, C1 and C2, are identical and independent. Each consists of the following: 1) A 10th order lowpass filter cut off at 3.1 kHz. 2) A balanced modulator with high baseband and carrier rejection. 3) A 3.3 kHz inversion carrier (injection tone). 4) A 14th order bandpass filter (300-3000 Hz). 5) Input op-amps with externally adjustable gain. The MX118 uses CMOS switched-capacitor filter technology and operates from a single supply in the range of 3.0 V to 5.5 V. The inversion carrier's frequency and filter switching clock are generated on-chip using an external 4.433619 MHz crystal or clock input. w w w .D at aS he et 4U .c om Figure 1 - Simplified Signal Paths * Electronics Communications Privacy Act (Title 18 US Code 2510 et seq.). www.DataSheet4U.com MX118 Figure 2 - Block Diagram ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ Component Value R1 1.0MΩ C1 1.0µF C2 33.0pF C3 47.0pF C4 0.47µF C5 1.0µF C6 1.0µF X1 4.433619 MHz Tolerances: R = ±10%, C = ±20% Notes: 1. Xtal circuitry shown is in ac...