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What should be considered when designing an ADC front end?
Optimizing the overall design depends on many factors, including the nature of the application, system partition, and ADC architecture. The following questions and answers highlight the important practical considerations affecting the design of an ADC front end using amplifier- and transformer circuitry.
Why do you need analog front end and how to set it up?
All the electronics on the sensor board — the sensor itself, the analog front end, the ASIC, and the memory — dramatically simplify what we must do to integrate this sensor with the microcontroller. In this case, just plug it into a few digital pins and install the library.
Why is the front end of a converter important?
Design of the input configuration, or “front end,” ahead of a high-performance analog-to-digital converter (ADC) is critical to achieving desired system performance. Optimizing the overall design depends on many factors, including the nature of the application, system partition, and ADC architecture.
What are the considerations of a wideband A / D converter?
Ask The Application Engineer—36: Wideband A/D Converter Front-End Design Considerations II: Amplifier-or Transformer Drive for the ADC? Design of the input configuration, or “front end,” ahead of a high-performance analog-to-digital converter (ADC) is critical to achieving desired system performance.
What’s the difference between the ADC and the amplifier?
The problem here is that the amplifier has a noise bandwidth equivalent to the full bandwidth of the ADC, around 500 MHz, while the ADC noise is folded to one Nyquist zone (40 MHz). Without a filter, the integrated noise then becomes 155 µV rms for the amplifier and 90 µV rms for the ADC.
What is the noise density of an amplifier?
A typical amplifier that might be considered, the ADA4937, for example, when configured for G = 1, has an output noise spectral density of 6 nV/rtHz at high frequencies, compared to the 10-nV/rtHz input noise spectral density of the 80-MSPS AD9446-80 ADC.
What is the capacitance of an ADC transformer?
The AD9246 ADC has a differential input capacitance of 4 pF which, coupled with the 200-ohm transformer impedance, reduces the ADC’s –3-dB bandwidth from 650 MHz to 200 MHz.