... | @@ -4,7 +4,7 @@ Doing the measurement of the board, we noticed, that harmonics level in |
... | @@ -4,7 +4,7 @@ Doing the measurement of the board, we noticed, that harmonics level in |
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the sine wave spectrum was to
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the sine wave spectrum was to
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high.
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high.
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![](/uploads/140e7ddf0fadb587fb9ae88714f54335/sine_no_filter.jpg)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/140e7ddf0fadb587fb9ae88714f54335/sine_no_filter.jpg)
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As you can see, the second harmonics is only 55 dB below the first
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As you can see, the second harmonics is only 55 dB below the first
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harmonic level. The sine wave source was the Rhode & Schwartz SML01
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harmonic level. The sine wave source was the Rhode & Schwartz SML01
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... | @@ -26,31 +26,31 @@ where edge sharpness is good. |
... | @@ -26,31 +26,31 @@ where edge sharpness is good. |
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Schematic of the
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Schematic of the
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filter:
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filter:
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![](/uploads/34ac4da4a98a9087e2a919296c504a1c/filter_schematic.jpg)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/34ac4da4a98a9087e2a919296c504a1c/filter_schematic.jpg)
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Simulated frequency
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Simulated frequency
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response:
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response:
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![](/uploads/62023f8bc7f751d1dbffc0f97735f005/filter_frequency_response.jpg)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/62023f8bc7f751d1dbffc0f97735f005/filter_frequency_response.jpg)
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Photo of the
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Photo of the
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filter:
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filter:
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![](/uploads/40a1fe40de6a627f897a8d5ca9408fca/P1040722.JPG)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/40a1fe40de6a627f897a8d5ca9408fca/P1040722.JPG)
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Measured frequency response - marker at the frequency that is
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Measured frequency response - marker at the frequency that is
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subharmonic of the sampling frequency (no "signal leakage" in FFT).
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subharmonic of the sampling frequency (no "signal leakage" in FFT).
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This is the frequency of our desired input signal
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This is the frequency of our desired input signal
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(the
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(the
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![](/uploads/40183edda830c26609c83dfec4912084/P1040720.JPG)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/40183edda830c26609c83dfec4912084/P1040720.JPG)
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Marker at the second harmonics. Filter's attenuation at this frequency
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Marker at the second harmonics. Filter's attenuation at this frequency
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is 46 dB (-4 dB for the base signal frequency).
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is 46 dB (-4 dB for the base signal frequency).
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It matches simulation results very
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It matches simulation results very
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well.
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well.
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![](/uploads/0c8296bbd8c6e74dc2cc9daabb13448f/P1040721.JPG)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/0c8296bbd8c6e74dc2cc9daabb13448f/P1040721.JPG)
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*Conclusion**
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*Conclusion**
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... | @@ -59,16 +59,16 @@ harmonics level of -90 dB and third harmonics of -80 dB. I don't have to |
... | @@ -59,16 +59,16 @@ harmonics level of -90 dB and third harmonics of -80 dB. I don't have to |
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add, that these values are much closer to our
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add, that these values are much closer to our
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estimations.
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estimations.
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![](/uploads/a52614e977c3f6023551f99645724c06/sine_filter.jpg)
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![](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/a52614e977c3f6023551f99645724c06/sine_filter.jpg)
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### Files
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### Files
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* [sine_no_filter.jpg](/uploads/140e7ddf0fadb587fb9ae88714f54335/sine_no_filter.jpg)
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* [sine_no_filter.jpg](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/140e7ddf0fadb587fb9ae88714f54335/sine_no_filter.jpg)
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* [P1040722.JPG](/uploads/40a1fe40de6a627f897a8d5ca9408fca/P1040722.JPG)
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* [P1040722.JPG](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/40a1fe40de6a627f897a8d5ca9408fca/P1040722.JPG)
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* [P1040720.JPG](/uploads/40183edda830c26609c83dfec4912084/P1040720.JPG)
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* [P1040720.JPG](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/40183edda830c26609c83dfec4912084/P1040720.JPG)
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* [P1040721.JPG](/uploads/0c8296bbd8c6e74dc2cc9daabb13448f/P1040721.JPG)
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* [P1040721.JPG](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/0c8296bbd8c6e74dc2cc9daabb13448f/P1040721.JPG)
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* [sine_filter.jpg](/uploads/a52614e977c3f6023551f99645724c06/sine_filter.jpg)
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* [sine_filter.jpg](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/a52614e977c3f6023551f99645724c06/sine_filter.jpg)
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* [filter_schematic.jpg](/uploads/34ac4da4a98a9087e2a919296c504a1c/filter_schematic.jpg)
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* [filter_schematic.jpg](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/34ac4da4a98a9087e2a919296c504a1c/filter_schematic.jpg)
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* [filter_frequency_response.jpg](/uploads/c17e05408f3fc2465a5cec4c32618018/filter_frequency_response.jpg)
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* [filter_frequency_response.jpg](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/c17e05408f3fc2465a5cec4c32618018/filter_frequency_response.jpg)
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* [filter_frequency_response.jpg](/uploads/62023f8bc7f751d1dbffc0f97735f005/filter_frequency_response.jpg) |
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* [filter_frequency_response.jpg](https://ohwr.org/project/fmc-adc-100m14b4cha/uploads/62023f8bc7f751d1dbffc0f97735f005/filter_frequency_response.jpg) |
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