DESCRIPTION

The LF2242 is a linear-phase, half band (low pass) interpolating/decimating digital filter that, unlike intricate analog filters, requires no tuning. The LF2242 can also significantly reduce the complexity of traditional analog anti-aliasing prefilters without compromising the signal bandwidth or attenuation. This can be achieved by using the LF2242 as a decimating post-filter with an A/D converter and by sampling the signal at twice the rate needed. Likewise, by using the LF2242 as an interpolating pre-filter with a D/A converter, the corresponding analog reconstruction post-filter circuitry can be simplified.

FEATURES

❑ 40 MHz Clock Rate

❑ Passband (0 to 0.22fS) Ripple: ±0.02 dB

❑ Stopband (0.28fS to 0.5fS) Rejection: 59.4 dB

❑ User-Selectable 2:1 Decimation or 1:2 Interpolation

❑ 12-bit Two’s Complement Input and 16-bit Output with User-Selectable Rounding, 8- to 16-Bits

❑ User-Selectable Two’s Complement or Inverted Offset Binary Output Formats

❑ Three-State Outputs

❑ Replaces TRW/ Raytheon/ Fairchild TMC2242

❑ Package Styles Available:

• 44-pin PLCC, J-Lead

• 44-pin PQFP