资料介绍
It may seem that designing a low noise, 12-bit Analog-to-Digital
Converter (ADC) board or even a 10-bit board is easy. This is
true, unless one ignores the basics of low noise design. For
instance, one would think that most amplifiers and resistors work
effectively in 12-bit or 10-bit environments. However, poor device
selection becomes a major factor in the success or failure of the
circuit. Another, often ignored, area that contributes a great deal
of noise, is conducted noise. Conducted noise is already in the
circuit board by the time the signal arrives at the input of the
ADC. The most effective way to remove this noise is by using a
low-pass (anti-aliasing) filter prior to the ADC. Including by-pass
capacitors and using a ground plane will also eliminate this type
of noise. A third source of noise is radiated noise. The major
sources of this type of noise are Electromagnetic Interference
(EMI) or capacitive coupling of signals from trace-to-trace. Techniques that Reduce System Noise
in ADC Circuits
By Bonnie C. Baker, Microchip Technology Inc.
ANALOG DESIGN NOTE ADN007
It may seem that designing a low noise, 12-bit Analog-to-Digital If this circuit is built without using low noise precautions,
Converter (ADC) board or even a 10-bit board is easy. This is it is very easy to produce an output similar to Figure 2.
true, unless one ignores the basics of low noise design. For Here, 1024 samples were taken at the output of the ADC
instance, one would think that most amplifiers and resistors work (MCP3201) at a data rate of 30 ksps. These samples have
effectively i
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