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