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reference:instrumentation:zmoddac:reference-manual [2019/10/30 12:48] – [2.3. AWG output stage protection] Mircea Dabacan | reference:instrumentation:zmoddac:reference-manual [2019/11/04 07:36] – [2.4. AWG Out] Mircea Dabacan | ||
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* Channel type: single ended | * Channel type: single ended | ||
* Resolution: | * Resolution: | ||
- | * Absolute Resolution (amplitude ≤1.25V): 152μV | + | * Absolute Resolution (amplitude ≤1.25V): 167μV |
- | * Absolute Resolution (amplitude > | + | * Absolute Resolution (amplitude > |
* Accuracy - typical (|Vout| ≤ 1.25V): ±10mV ± 0.5% FIXME | * Accuracy - typical (|Vout| ≤ 1.25V): ±10mV ± 0.5% FIXME | ||
* Accuracy - typical (|Vout| > 1.25V): ±25mV ± 0.5% FIXME | * Accuracy - typical (|Vout| > 1.25V): ±25mV ± 0.5% FIXME | ||
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$$at\; | $$at\; | ||
- | $$at\; | + | $$at\; |
- | AD8021 is supplied with $\pm 8V$; to avoid saturation | + | AD8021 is supplied with +8.5V/-8V (the VCC8V0 voltage is in fact 8.5V). Conform |
- | $$ - 6.5V < -5V < V_{AWG\; | + | The nominal resistance of the PTC in the feedback loop is 33 ohm. The maximum current delivered by te AWG is 30mA. |
+ | |||
+ | To avoid saturation, the voltage in \ref{9} should stay in: | ||
+ | |||
+ | $$ -8V + 1.8V + 33\Omega *30mA = -5.21V | ||
Only inner (tighter) ranges are used in equations \ref{10} and \ref{12}, for providing tolerance margins. | Only inner (tighter) ranges are used in equations \ref{10} and \ref{12}, for providing tolerance margins. | ||
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To trace the analog bandwidth of the DAC and output stage beyond the theoretical limit of f< | To trace the analog bandwidth of the DAC and output stage beyond the theoretical limit of f< | ||
- | * The AWG was set to generate a 20MGz rectangular signal, 100mV amplitude; | + | * The AWG was set to generate a 2MHz rectangular signal, 100mV amplitude; |
* the theoretical amplitudes of the fundamental and first 69 harmonics was computed; | * the theoretical amplitudes of the fundamental and first 69 harmonics was computed; | ||
- | * the actual amplitudes of the fundamental and first 69 harmonics | + | * the actual amplitudes of the fundamental and first 69 harmonics |
* the dB difference between the theoretical and measured amplitudes was plotted. This represents an approximation of the frequency characteristic of the DAC and output stage. | * the dB difference between the theoretical and measured amplitudes was plotted. This represents an approximation of the frequency characteristic of the DAC and output stage. | ||
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The 3dB bandwidth is close to the theoretical Nyquist limit for a 100MHz sampling system. This has the advantage of very sharp edges (see the rectangular signal in [[reference: | The 3dB bandwidth is close to the theoretical Nyquist limit for a 100MHz sampling system. This has the advantage of very sharp edges (see the rectangular signal in [[reference: | ||
- | the right side of [[reference: | + | the right side of [[reference: |
The typical Slew Rate of the AWG can be read in [[reference: | The typical Slew Rate of the AWG can be read in [[reference: | ||
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==== 4.3. AVCC8V0 ==== | ==== 4.3. AVCC8V0 ==== | ||
- | The user power supplies [[reference: | + | The user power supplies [[reference: |
* 1.4A current limit | * 1.4A current limit | ||
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==== 4.4. AVCC-8V0 ==== | ==== 4.4. AVCC-8V0 ==== | ||
- | The user power supplies [[reference: | + | The user power supplies [[reference: |
IC13 introduces the required inversion for the negative supply. [[https:// | IC13 introduces the required inversion for the negative supply. [[https:// |