FX304

Duplex Filter Array

The FX304 is a duplex filter array and scrambler.

Full Duplex Audio Processing
Designed to meet Net-C Cellular Specification
On-Chip Audio Bandpass Filters (300-3000Hz)
Fixed Frequency Inversion
Clear/Invert Facility
Output Enable/Disable

High Baseband and Carrier Rejection
Independent I/P Gain Adjustment
On-Chip Clock Oscillator Circuits
Crystal Oscillator Stability
Single 5V CMOS Process
Surface Mount and DIL Package Styles

The FX304 is a duplex filter array and frequency inversion scrambler compatible with the Net-C specification. The two channels, C1 and C2, are identical and independent, each consisting of:

A 10th order 3.1 kHz input low pass filter in the 'Invert' path.
A balanced modulator providing fixed frequency inversion (3.3 kHz) and having high baseband and carrier rejection.
A 14th order bandpass filter (300Hz to 3 kHz).
Input Op-Amps in both 'Clear' and 'Invert' paths allowing external components to set input gains, and pre-emphasis or de-emphasis in the 'Clear' path.
Clear/ Invert switching causing automatic changeover of signal routes and input circuitry.
A buffered low noise output with switching clock filter.
An Output Enable switching facility.

Both filter sets meet the Net-C specification and use switched capacitor technology. The common carrier frequency and filter switching clock are generated on-chip using an external 4.433619MHz Xtal or clock input.

Grey ceramic case.