LF2242

LF2242 DEVICES INCORPORATED DEVICES INCORPORATED 12/16-bit Half-Band Interpolating/ Decimating Digital Filter DESCRIPTION The LF2242 is a linear-phase, halfband (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. The coefficients of the LF2242 are fixed, and the only user programming required is the selection of the mode (interpolate, decimate, or passthrough) and rounding. The asynchronous three-state output enable control simplifies interfacing to a bus. Data can be input into the LF2242 at a rate of up to 40 million samples per second. Within the 40 MHz I/O limit, the output sample rate can be onehalf, equal to, or two times the input 12/16-bit Half-Band Interpolating/ Decimating Digital Filter LF2242 FEATURES u 40 MHz Clock Rate u Passband (0 to 0.22fS) Ripple: ±0.02 dB u Stopband (0.28fS to 0.5fS) Rejection: 59.4 dB u User-Selectable 2:1 Decimation or 1:2 Interpolation u 12-bit Two’s Complement Input and 16-bit Output with User-Selectable Rounding,...