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title = "Analog to Digital Converters"
author = ["Thomas Dehaeze"]
author = ["Dehaeze Thomas"]
keywords = ["electronics"]
draft = false
category = "equipment"
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Tags
: [Electronics]({{<relref "electronics.md#" >}})
: [Electronics]({{< relref "electronics.md" >}})
## Types of Analog to Digital Converters {#types-of-analog-to-digital-converters}
<https://dewesoft.com/daq/types-of-adc-converters>
- Delta Sigma ([Baker 2011](#orgbdb61af))
- Delta Sigma <baker11_how_delta_sigma_adcs_work_part>
- Successive Approximation
@@ -33,11 +33,11 @@ Let's suppose that the ADC is ideal and the only noise comes from the quantizati
Interestingly, the noise amplitude is uniformly distributed.
The quantization noise can take a value between \\(\pm q/2\\), and the probability density function is constant in this range (i.e., its a uniform distribution).
Since the integral of the probability density function is equal to one, its value will be \\(1/q\\) for \\(-q/2 < e < q/2\\) (Fig. [1](#org4bd731c)).
Since the integral of the probability density function is equal to one, its value will be \\(1/q\\) for \\(-q/2 < e < q/2\\) (Fig. [1](#figure--fig:probability-density-function-adc)).
<a id="org4bd731c"></a>
<a id="figure--fig:probability-density-function-adc"></a>
{{< figure src="/ox-hugo/probability_density_function_adc.png" caption="Figure 1: Probability density function \\(p(e)\\) of the ADC error \\(e\\)" >}}
{{< figure src="/ox-hugo/probability_density_function_adc.png" caption="<span class=\"figure-number\">Figure 1: </span>Probability density function \\(p(e)\\) of the ADC error \\(e\\)" >}}
Now, we can calculate the time average power of the quantization noise as
@@ -59,13 +59,12 @@ Thus, the two-sided PSD (from \\(\frac{-f\_s}{2}\\) to \\(\frac{f\_s}{2}\\)), we
\end{equation}
<div class="important">
<div></div>
Finally, the Power Spectral Density of the quantization noise of an ADC is equal to:
\begin{equation}
\begin{aligned}
\Gamma &= \frac{q^2}{12 f\_s} \\\\\\
\Gamma &= \frac{q^2}{12 f\_s} \\\\
&= \frac{\left(\frac{\Delta V}{2^n}\right)^2}{12 f\_s} \text{ in } \left[ \frac{V^2}{Hz} \right]
\end{aligned}
\end{equation}
@@ -73,7 +72,6 @@ Finally, the Power Spectral Density of the quantization noise of an ADC is equal
</div>
<div class="exampl">
<div></div>
Let's take a 18bits ADC with a range of +/-10V and a sample frequency of 10kHz.
@@ -87,7 +85,4 @@ The quantization is:
{{< youtube b9lxtOJj3yU >}}
## Bibliography {#bibliography}
<a id="orgbdb61af"></a>Baker, Bonnie. 2011. “How Delta-Sigma Adcs Work, Part.” _Analog Applications_ 7.
## Oversampling {#oversampling}