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<h1 class="title">Voltage Amplifier PD200 - Test Bench</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#org9fe8e60">1. Introduction</a></li>
<li><a href="#org83288a7">2. Voltage Amplifier Requirements</a></li>
<li><a href="#org2725a7d">3. PD200 Expected characteristics</a></li>
<li><a href="#org6748772">4. Voltage Amplifier Model</a></li>
<li><a href="#orgb0f1751">5. Noise measurement</a>
<ul>
<li><a href="#org077faf1">5.1. Setup</a></li>
<li><a href="#org8d11397">5.2. Results</a>
<ul>
<li><a href="#org3e569c9">5.2.1. Noise when shunting the input (50 Ohms)</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#orgaf96727">6. Transfer Function measurement</a>
<ul>
<li><a href="#org9868c43">6.1. Setup</a></li>
<li><a href="#orgc5c49ee">6.2. Results</a></li>
</ul>
</li>
<li><a href="#org516bcbb">7. Conclusion</a></li>
</ul>
</div>
</div>
<div id="outline-container-org9fe8e60" class="outline-2">
<h2 id="org9fe8e60"><span class="section-number-2">1</span> Introduction</h2>
<div class="outline-text-2" id="text-1">
<p>
The goal of this test bench is to characterize the Voltage amplifier <a href="https://www.piezodrive.com/drivers/pd200-60-watt-voltage-amplifier/">PD200</a> from PiezoDrive.
</p>
<p>
The documentation of the PD200 is accessible <a href="doc/PD200-V7-R1.pdf">here</a>.
</p>
<div id="orga2cd341" class="figure">
<p><img src="figs/amplifier_PD200.png" alt="amplifier_PD200.png" />
</p>
<p><span class="figure-number">Figure 1: </span>Picture of the PD200 Voltage Amplifier</p>
</div>
</div>
</div>
<div id="outline-container-org83288a7" class="outline-2">
<h2 id="org83288a7"><span class="section-number-2">2</span> Voltage Amplifier Requirements</h2>
<div class="outline-text-2" id="text-2">
<table id="org6825b69" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption class="t-above"><span class="table-number">Table 1:</span> Requirements for the Voltage Amplifier</caption>
<colgroup>
<col class="org-left" />
<col class="org-center" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">&#xa0;</th>
<th scope="col" class="org-center"><b>Specification</b></th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left">Continuous Current</td>
<td class="org-center">&gt; 50 [mA]</td>
</tr>
<tr>
<td class="org-left">Output Voltage Noise (1-200Hz)</td>
<td class="org-center">&lt; 2 [mV rms]</td>
</tr>
<tr>
<td class="org-left">Voltage Input Range</td>
<td class="org-center">+/- 10 [V]</td>
</tr>
<tr>
<td class="org-left">Voltage Output Range</td>
<td class="org-center">-20 [V] to 150 [V]</td>
</tr>
<tr>
<td class="org-left">Small signal bandwidth (-3dB)</td>
<td class="org-center">&gt; 5 [kHz]</td>
</tr>
</tbody>
</table>
</div>
</div>
<div id="outline-container-org2725a7d" class="outline-2">
<h2 id="org2725a7d"><span class="section-number-2">3</span> PD200 Expected characteristics</h2>
<div class="outline-text-2" id="text-3">
<table id="orgf99d960" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption class="t-above"><span class="table-number">Table 2:</span> Characteristics of the PD200</caption>
<colgroup>
<col class="org-left" />
<col class="org-center" />
<col class="org-center" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left"><b>Characteristics</b></th>
<th scope="col" class="org-center"><b>Manual</b></th>
<th scope="col" class="org-center"><b>Specification</b></th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left">Input Voltage Range</td>
<td class="org-center">+/- 10 [V]</td>
<td class="org-center">+/- 10 [V]</td>
</tr>
<tr>
<td class="org-left">Output Voltage Range</td>
<td class="org-center">-50/150 [V]</td>
<td class="org-center">-20/150 [V]</td>
</tr>
<tr>
<td class="org-left">Gain</td>
<td class="org-center">20 [V/V]</td>
<td class="org-center">&#xa0;</td>
</tr>
<tr>
<td class="org-left">Maximum RMS current</td>
<td class="org-center">0.9 [A]</td>
<td class="org-center">&gt; 50 [mA]</td>
</tr>
<tr>
<td class="org-left">Maximum Pulse current</td>
<td class="org-center">10 [A]</td>
<td class="org-center">&#xa0;</td>
</tr>
<tr>
<td class="org-left">Slew Rate</td>
<td class="org-center">150 [V/us]</td>
<td class="org-center">&#xa0;</td>
</tr>
<tr>
<td class="org-left">Noise (10uF load)</td>
<td class="org-center">0.7 [mV RMS]</td>
<td class="org-center">&lt; 2 [mV rms]</td>
</tr>
<tr>
<td class="org-left">Small Signal Bandwidth (10uF load)</td>
<td class="org-center">7.4 [kHz]</td>
<td class="org-center">&gt; 5 [kHz]</td>
</tr>
<tr>
<td class="org-left">Large Signal Bandwidth (150V, 10uF)</td>
<td class="org-center">300 [Hz]</td>
<td class="org-center">&#xa0;</td>
</tr>
</tbody>
</table>
<p>
For a load capacitance of \(10\,\mu F\), the expected \(-3\,dB\) bandwidth is \(6.4\,kHz\) (Figure <a href="#orgf39e37f">2</a>) and the low frequency noise is \(650\,\mu V\,\text{rms}\) (Figure <a href="#org2267cad">3</a>).
</p>
<div id="orgf39e37f" class="figure">
<p><img src="./figs/pd200_expected_small_signal_bandwidth.png" alt="pd200_expected_small_signal_bandwidth.png" />
</p>
<p><span class="figure-number">Figure 2: </span>Expected small signal bandwidth</p>
</div>
<div id="org2267cad" class="figure">
<p><img src="figs/pd200_expected_noise.png" alt="pd200_expected_noise.png" />
</p>
<p><span class="figure-number">Figure 3: </span>Expected Low frequency noise from 0.03Hz to 20Hz</p>
</div>
</div>
</div>
<div id="outline-container-org6748772" class="outline-2">
<h2 id="org6748772"><span class="section-number-2">4</span> Voltage Amplifier Model</h2>
<div class="outline-text-2" id="text-4">
<p>
The Amplifier is characterized by its dynamics \(G_a(s)\) from voltage inputs \(V_{in}\) to voltage output \(V_{out}\).
Ideally, the gain from \(V_{in}\) to \(V_{out}\) is constant over a wide frequency band with very small phase drop.
</p>
<p>
It is also characterized by its output noise \(n\).
This noise is described by its Power Spectral Density.
</p>
<p>
The objective is therefore to determine the transfer function \(G_a(s)\) from the input voltage to the output voltage as well as the Power Spectral Density \(S_n(\omega)\) of the amplifier output noise.
</p>
<p>
As both \(G_a\) and \(S_n\) depends on the load capacitance, they should be measured when loading the amplifier with a \(\SI{10}{\micro\farad}\) capacitor.
</p>
<div id="org4313e25" class="figure">
<p><img src="figs/pd200-model-schematic.png" alt="pd200-model-schematic.png" />
</p>
<p><span class="figure-number">Figure 4: </span>Model of the voltage amplifier</p>
</div>
</div>
</div>
<div id="outline-container-orgb0f1751" class="outline-2">
<h2 id="orgb0f1751"><span class="section-number-2">5</span> Noise measurement</h2>
<div class="outline-text-2" id="text-5">
</div>
<div id="outline-container-org077faf1" class="outline-3">
<h3 id="org077faf1"><span class="section-number-3">5.1</span> Setup</h3>
<div class="outline-text-3" id="text-5-1">
<div class="note" id="org3d87176">
<p>
Here are the documentation of the equipment used for this test bench:
</p>
<ul class="org-ul">
<li>Voltage Amplifier <a href="doc/PD200-V7-R1.pdf">PD200</a></li>
<li>Load Capacitor <a href="doc/0900766b815ea422.pdf">EPCOS 10uF Multilayer Ceramic Capacitor</a></li>
<li>Low Noise Voltage Amplifier <a href="doc/egg-5113-preamplifier.pdf">EG&amp;G 5113</a></li>
<li>Speedgoat ADC <a href="doc/IO131-OEM-Datasheet.pdf">IO313</a></li>
</ul>
</div>
<p>
The output noise of the voltage amplifier PD200 is foreseen to be around 1mV rms in a bandwidth from DC to 1MHz.
If we suppose a white noise, this correspond to an amplitude spectral density:
</p>
\begin{equation}
\phi_{n} \approx \frac{1\,mV}{\sqrt{1\,MHz}} = 1 \frac{\mu V}{\sqrt{Hz}}
\end{equation}
<p>
The RMS noise begin very small compare to the ADC resolution, we must amplify the noise before digitizing the signal.
The added noise of the instrumentation amplifier should be much smaller than the noise of the PD200.
We use the amplifier EG&amp;G 5113 that has a noise of \(\approx 4 nV/\sqrt{Hz}\) referred to its input which is much smaller than the noise induced by the PD200.
</p>
<p>
The gain of the low-noise amplifier can be increased until the full range of the ADC is used.
This gain should be around 1000.
</p>
<div id="orgb37f1e6" class="figure">
<p><img src="figs/setup-noise-measurement.png" alt="setup-noise-measurement.png" />
</p>
<p><span class="figure-number">Figure 5: </span>Schematic of the test bench to measure the Power Spectral Density of the Voltage amplifier noise \(n\)</p>
</div>
<p>
A low pass filter at 10kHz can be included in the EG&amp;G amplifier in order to limit aliasing.
An high pass filter at low frequency can be added if there is a problem of large offset.
</p>
</div>
</div>
<div id="outline-container-org8d11397" class="outline-3">
<h3 id="org8d11397"><span class="section-number-3">5.2</span> Results</h3>
<div class="outline-text-3" id="text-5-2">
</div>
<div id="outline-container-org3e569c9" class="outline-4">
<h4 id="org3e569c9"><span class="section-number-4">5.2.1</span> Noise when shunting the input (50 Ohms)</h4>
<div class="outline-text-4" id="text-5-2-1">
<p>
The time domain measurements of the amplifier noise are shown in Figure <a href="#org6fb276a">6</a>.
</p>
<div id="org6fb276a" class="figure">
<p><img src="figs/noise_shunt_time_3uF.png" alt="noise_shunt_time_3uF.png" />
</p>
<p><span class="figure-number">Figure 6: </span>Time domain measurement of the amplifier output noise</p>
</div>
<p>
Obtained low frequency (0.1Hz - 20Hz) noise is shown in Figure <a href="#orgaadf193">7</a> which is very similar to the noise shown in the documentation (Figure <a href="#org2267cad">3</a>).
</p>
<div id="orgaadf193" class="figure">
<p><img src="figs/low_noise_time_domain_3uF.png" alt="low_noise_time_domain_3uF.png" />
</p>
<p><span class="figure-number">Figure 7: </span>Low Frequency Noise (0.1Hz - 20Hz)</p>
</div>
<p>
The obtained RMS and peak to peak values of the measured noises are shown in Table <a href="#orgd174c39">3</a>.
</p>
<table id="orgd174c39" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption class="t-above"><span class="table-number">Table 3:</span> RMS and Peak to Peak measured noise</caption>
<colgroup>
<col class="org-left" />
<col class="org-right" />
<col class="org-right" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">&#xa0;</th>
<th scope="col" class="org-right"><b>RMS [uV]</b></th>
<th scope="col" class="org-right"><b>Peak to Peak [mV]</b></th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left">Specification [10uF]</td>
<td class="org-right">714.0</td>
<td class="org-right">4.3</td>
</tr>
<tr>
<td class="org-left">PD200_1</td>
<td class="org-right">524.9</td>
<td class="org-right">4.5</td>
</tr>
<tr>
<td class="org-left">PD200_2</td>
<td class="org-right">807.7</td>
<td class="org-right">6.7</td>
</tr>
<tr>
<td class="org-left">PD200_3</td>
<td class="org-right">630.3</td>
<td class="org-right">5.4</td>
</tr>
<tr>
<td class="org-left">PD200_4</td>
<td class="org-right">619.7</td>
<td class="org-right">5.5</td>
</tr>
<tr>
<td class="org-left">PD200_5</td>
<td class="org-right">630.8</td>
<td class="org-right">5.6</td>
</tr>
<tr>
<td class="org-left">PD200_6</td>
<td class="org-right">517.3</td>
<td class="org-right">4.9</td>
</tr>
<tr>
<td class="org-left">PD200_7</td>
<td class="org-right">393.8</td>
<td class="org-right">3.7</td>
</tr>
</tbody>
</table>
<p>
The PSD of the measured noise is computed and the ASD is shown in Figure <a href="#org17a3769">8</a>.
</p>
<div class="org-src-container">
<pre class="src src-matlab">win = hanning(ceil(0.5<span class="org-type">/</span>Ts));
[pxx, f] = pwelch(pd200{1}.Vn, win, [], [], Fs);
pxx = zeros(length(pxx), 7);
<span class="org-keyword">for</span> <span class="org-variable-name"><span class="org-constant">i</span></span> = <span class="org-constant">1:7</span>
pxx(<span class="org-type">:</span>, <span class="org-constant">i</span>) = pwelch(pd200{<span class="org-constant">i</span>}.Vn, win, [], [], Fs);
<span class="org-keyword">end</span>
</pre>
</div>
<div id="org17a3769" class="figure">
<p><img src="figs/asd_noise_3uF.png" alt="asd_noise_3uF.png" />
</p>
<p><span class="figure-number">Figure 8: </span>Amplitude Spectral Density of the measured noise</p>
</div>
</div>
</div>
</div>
</div>
<div id="outline-container-orgaf96727" class="outline-2">
<h2 id="orgaf96727"><span class="section-number-2">6</span> Transfer Function measurement</h2>
<div class="outline-text-2" id="text-6">
</div>
<div id="outline-container-org9868c43" class="outline-3">
<h3 id="org9868c43"><span class="section-number-3">6.1</span> Setup</h3>
<div class="outline-text-3" id="text-6-1">
<p>
In order to measure the transfer function from the input voltage \(V_{in}\) to the output voltage \(V_{out}\), the test bench shown in Figure <a href="#org472ad71">9</a> is used.
</p>
<div class="note" id="org5cbd7bf">
<p>
Here are the documentation of the equipment used for this test bench:
</p>
<ul class="org-ul">
<li>Voltage Amplifier <a href="doc/PD200-V7-R1.pdf">PD200</a></li>
<li>Load Capacitor <a href="doc/0900766b815ea422.pdf">EPCOS 10uF Multilayer Ceramic Capacitor</a></li>
<li>Speedgoat DAC/ADC <a href="doc/IO131-OEM-Datasheet.pdf">IO313</a></li>
</ul>
</div>
<p>
For this measurement, the sampling frequency of the Speedgoat ADC should be as high as possible.
</p>
<div id="org472ad71" class="figure">
<p><img src="figs/setup-dynamics-measurement.png" alt="setup-dynamics-measurement.png" />
</p>
<p><span class="figure-number">Figure 9: </span>Schematic of the test bench to estimate the dynamics from voltage input \(V_{in}\) to voltage output \(V_{out}\)</p>
</div>
</div>
</div>
<div id="outline-container-orgc5c49ee" class="outline-3">
<h3 id="orgc5c49ee"><span class="section-number-3">6.2</span> Results</h3>
</div>
</div>
<div id="outline-container-org516bcbb" class="outline-2">
<h2 id="org516bcbb"><span class="section-number-2">7</span> Conclusion</h2>
<div class="outline-text-2" id="text-7">
<table id="orgcddfe96" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption class="t-above"><span class="table-number">Table 4:</span> Measured characteristics, Manual characterstics and specified ones</caption>
<colgroup>
<col class="org-left" />
<col class="org-center" />
<col class="org-center" />
<col class="org-center" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left"><b>Characteristics</b></th>
<th scope="col" class="org-center"><b>Measurement</b></th>
<th scope="col" class="org-center"><b>Manual</b></th>
<th scope="col" class="org-center"><b>Specification</b></th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left">Input Voltage Range</td>
<td class="org-center">-</td>
<td class="org-center">+/- 10 [V]</td>
<td class="org-center">+/- 10 [V]</td>
</tr>
<tr>
<td class="org-left">Output Voltage Range</td>
<td class="org-center">-</td>
<td class="org-center">-50/150 [V]</td>
<td class="org-center">-20/150 [V]</td>
</tr>
<tr>
<td class="org-left">Gain</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">20 [V/V]</td>
<td class="org-center">-</td>
</tr>
<tr>
<td class="org-left">Maximum RMS current</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">0.9 [A]</td>
<td class="org-center">&gt; 50 [mA]</td>
</tr>
<tr>
<td class="org-left">Maximum Pulse current</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">10 [A]</td>
<td class="org-center">-</td>
</tr>
<tr>
<td class="org-left">Slew Rate</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">150 [V/us]</td>
<td class="org-center">-</td>
</tr>
<tr>
<td class="org-left">Noise (10uF load)</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">0.7 [mV RMS]</td>
<td class="org-center">&lt; 2 [mV rms]</td>
</tr>
<tr>
<td class="org-left">Small Signal Bandwidth (10uF load)</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">7.4 [kHz]</td>
<td class="org-center">&gt; 5 [kHz]</td>
</tr>
<tr>
<td class="org-left">Large Signal Bandwidth (150V, 10uF)</td>
<td class="org-center">&#xa0;</td>
<td class="org-center">300 [Hz]</td>
<td class="org-center">-</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<div id="postamble" class="status">
<p class="author">Author: Dehaeze Thomas</p>
<p class="date">Created: 2021-01-19 mar. 23:00</p>
</div>
</body>
</html>