an optimized R2R-DAC
with 0,5% precision |
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DSP Module
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A simple
R2R-based DAC for signal generation in audio and video
applications with
0,5% error is shown belw. It is based on standard "golden" resistors with
5% tolerance. The circuit is controlled
by up tp 10 bits using a current Spartan 2 FPGA from Xilinx.
10-Bit-DAC with calibration option
Calibration method:
6
Bits of a common R2R-32-Step-DAC are extended by additional
4 bits with optimized values R4,R6,R8 to be able to calibrate
any deviation from the ideal curve. The calibration range is
+/- 5,2% which is enough if at least the most important two
resistors meet in values well enough. In case more
compensation is required, the B-Pins have to be shifted one
position to the right using the values R6, R4, R2,R2.
Application examples:
With
the Spartan FPGA, a highly precise signal generator can be
built running at 48MHz which is almost suitable for simple
audio output using oversampling strategies and pulse density
modulation methods possibly using for bass frequencies when
adding good filtering. YC-Video can be generate easily with high quality too.
See an example for a noise generator using this ladder:
Noise
generator in a FPGA
Read more about the R2R-DAC here:
optimized 8
Bit DAC
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Spartan II
FPGA
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48 kHz Audio
DSP |
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