
Fairchild Semiconductor
Description
The TMC2242C, a linear-phase low-pass half-band digital filter with fixed coefficients, can be used to halve or double the sampling rate of a digital signal. When used as a decimating post-filter with a double-speed oversampling A/D converter, it greatly reduces the cost and complexity of the required analog antialiasing pre-filters. When used as an interpolating pre-filter with a double-speed oversampling D/A converter, it greatly reduces the complexity and cost of the necessary analog post-filter, particularly when its x/sin(x) correction filter is engaged.
FEATUREs
• Pin-compatible upgrade of TMC2242B
• User-selectable interpolate d.c. gain, 0 dB or -6 dB
• True unity d.c. gain in all “0 db” modes
• 40 MSPS performance in equal-rate filter modes
• 40 and 60 MSPS speed grades in all other modes
• User-selectable 2:1 decimation, 1:2 interpolation, and equal-rate filter modes, plus unfiltered bypass/delay mode
• Defeatable πx/sin(πx) compensation filter
• Passband ripple <0.014 dB
• Stopband rejection >56 dB
• Dedicated 12-bit two’s complement or unsigned input bus
• 16-bit two’s complement or unsigned output bus with user-selectable rounding to 8 to 16 effective bits
• Programmable limiter prevents overflow or clips to CCIR601 levels
• New double-latency modes match Y channel data flow to slower-sampled CB and CR data flows
• New dual-channel interpolation and decimation for YUV422
APPLICATIONs
• Digital-to-Analog Converter Prefiltering with optional x/sinx correction
• 1:2 interpolation
• Analog-to-Digital Converter Postfiltering
• 2:1 decimation
• Low-ripple low-pass (0 to 0.2 fs) filter