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TMC2242A/TMC2242B
Digital Half-Band Interpolating/Decimating Filter
12-bit In/16-bit Out, 60 MHz
Features
• TMC2242A and TMC2242B are pin-compatible with
TMC2242
• User selectable interpolate gain, -6 dB or 0 dB (2242B)
• 30, 40 and 60 MHz speed grades
• User selectable 2:1 decimation, 1:2 interpolation, and
equal-rate filter modes
• Passband ripple <
±
0.01 dB
• Stopband rejection 59.4 dB from 0.28 to 0.50 x f
s
• Cascading two TMC2242A or TMC2242B meets
CCIR 601 low-pass filter requirement
• Dedicated 12-bit 2's complement input data port and
16-bit output data port with user-selectable rounding from
9 to 16 bits
• Two's complement or offset binary output format
• Built-in limiter prevents overflow
• Single +5 Volt power supply operation
• Small 44-Lead PLCC and 44-Lead MQFP
Applications
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Low-cost video filtering
Chrominance bandwidth limiter
Simple, inexpensive video D/A post-filters
Reduced cost and complexity for A/D anti-aliasing filters
High-performance digital low-pass filters
Digital waveform reconstruction post-filtering
Telecommunications
Direct digital synthesis
Radar
Description
The TMC2242A and TMC2242B are fixed-coefficient lin-
ear-phase half-band (low-pass) digital filters. They 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, they greatly reduce the cost and
complexity of anti-aliasing filters required ahead of the A/D
converter. When used as an interpolating pre-filter with a
double-speed oversampling D/A converter, the TMC2242A
and TMC2242B significantly reduce the design complexity
and production cost of reconstruction filters used on D/A
outputs.
The TMC2242A and TMC2242B user selects the mode of
operation (decimate, interpolate, or equal-rate) and round-
ing. The TMC2242A and TMC2242B accept 12-bit 2's com-
plement data at up to 60 MHz and output saturated
(overflow-protected) 2's complement or offset binary data
rounded to from 9 to 16 bits. Within the speed grade I/O
limit, the output sample rate may be 1/2, 1, or 2 times the
input sample rate.
Block Diagram
12
SI
11-0
12
12
12
55 Tap
FIR
Filter
Round
and
Limit
16
16
16
SO
15-0
OE
CLK
DEC
INT
SYNC
Control
Interpolate 0-1-0-1
Decimate, Equal Rate 1-1-1-1
3
TCO
RND
2-0
65-2242A-01
Rev. 1.2.0
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
