NMT Audio Filter Array


The FX316 is designed to meet NMT Base and Mobile specifications.

  • Cellular Radio Audio Processing
  • NMT 450 & 900MHz Base Station and Mobile Specifications
  • High Order Lowpass Filter including SAT Rejection
  • Low Group Delay Distortion
  • 4 kHz SAT Recovery Bandpass
  • Uncommitted Amplifier
  • Switched Capacitor Filters
  • Xtal Controlled
  • Single 5 Volt CMOS Process
  • Chip Enable Powersave Feature
  • Surface Mount or DIL Package

The FX316 is a low power CMOS Switched Capacitor Filter array designed to meet NMT Base and Mobile specifications. The device in detail consists of:

  1. a 12th order 3.4 kHz low pass filter with sufficient rejection of 4 kHz signals to meet NMT 450 and 900 filter response specifications for both base and mobile equipment. The low pass filter also provides a low group delay distortion path.
  2. a 6th order 4 kHz narrow bandpass filter which meets the NMT 450 and 900 mobile specifications for SAT recovery.
  3. an uncommitted amplifier which may be used for any specific applications such as pre- emphasis, de-emphasis, buffering, etc.
An on-chip oscillator uses a 1MHz Xtal and provides all reference clocks for the switched capacitor filters via a divider chain. Alternatively, an external clock may be used. The Chip Enable feature is used to disable the three circuit elements thus reducing current consumption.