adc2:simulations:fft_freq_mismatch
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adc2:simulations:fft_freq_mismatch [2009/11/20 22:57] szymon.kulis |
adc2:simulations:fft_freq_mismatch [2019/03/08 14:08] (current) |
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| ^ diff [hz] ^ % fbase ^ left [dB] ^ right [dB] ^ SINAD [dB] ^ THD [dB] ^ SNHR [dB] ^ SFDR [dB] ^ | ^ diff [hz] ^ % fbase ^ left [dB] ^ right [dB] ^ SINAD [dB] ^ THD [dB] ^ SNHR [dB] ^ SFDR [dB] ^ | ||
| - | | 36.62 | 3.00 | -30.7 | -30.2 | 25.3 | -83.6 | 25.3 | 30.2 | | + | | 36.62 | 3.00 | -30.7 | -30.2 | 25.3 | -83.6 | 25.3 | 30.2 | |
| - | | 61.04 | 5.00 | -26.4 | -25.6 | 20.8 | -79.1 | 20.8 | 25.6 | | + | | 61.04 | 5.00 | -26.4 | -25.6 | 20.8 | -79.1 | 20.8 | 25.6 | |
| - | | 109.86 | 9.00 | -21.7 | -20.1 | 15.7 | -74.0 | 15.7 | 20.1 | | + | | 109.86 | 9.00 | -21.7 | -20.1 | 15.7 | -74.0 | 15.7 | 20.1 | |
| - | | 207.52 | 17.00 | -16.8 | -13.8 | 10.0 | -68.5 | 10.0 | 13.8 | | + | | 207.52 | 17.00 | -16.8 | -13.8 | 10.0 | -68.5 | 10.0 | 13.8 | |
| {{:adc2:simulations:fsim_diff_coarse.png|}} | {{:adc2:simulations:fsim_diff_coarse.png|}} | ||
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| {{:adc2:simulations:fsim_fft_coarse.png|}} | {{:adc2:simulations:fsim_fft_coarse.png|}} | ||
| + | ^ diff [hz] ^ % fbase ^ left [dB] ^ right [dB] ^ SINAD [dB] ^ THD [dB] ^ SNHR [dB] ^ SFDR [dB] ^ | ||
| + | | -37.84 | -3.10 | -29.9 | -30.4 | 25.0 | -83.4 | 25.0 | 29.9 | | ||
| + | | -20.75 | -1.70 | -35.2 | -35.5 | 30.2 | -88.6 | 30.2 | 35.2 | | ||
| + | | -10.99 | -0.90 | -40.8 | -41.0 | 35.7 | -94.1 | 35.7 | 40.8 | | ||
| + | | -6.10 | -0.50 | -46.0 | -46.1 | 40.8 | -99.2 | 40.8 | 46.0 | | ||
| + | | -3.66 | -0.30 | -50.4 | -50.5 | 45.3 | -103.6 | 45.3 | 50.4 | | ||
| + | | -2.44 | -0.20 | -54.0 | -54.0 | 48.8 | -107.2 | 48.8 | 54.0 | | ||
| + | | -1.22 | -0.10 | -60.0 | -60.0 | 54.8 | -113.2 | 54.8 | 60.0 | | ||
| + | |||
| + | {{:adc2:simulations:fsim_diff_fine.png|}} | ||
| + | {{:adc2:simulations:fsim_fft_fine.png|}} | ||
| + | |||
| + | ^ diff [hz] ^ % fbase ^ left [dB] ^ right [dB] ^ SINAD [dB] ^ THD [dB] ^ SNHR [dB] ^ SFDR [dB] ^ | ||
| + | | -3.78 | -0.31 | -50.1 | -50.2 | 45.0 | -103.4 | 45.0 | 50.1 | | ||
| + | | -2.08 | -0.17 | -55.4 | -55.4 | 50.2 | -108.6 | 50.2 | 55.4 | | ||
| + | | -1.22 | -0.10 | -60.0 | -60.0 | 54.8 | -113.2 | 54.8 | 60.0 | | ||
| + | | -0.61 | -0.05 | -66.0 | -66.0 | 60.8 | -119.2 | 60.8 | 66.0 | | ||
| + | | -0.38 | -0.03 | -70.2 | -70.2 | 65.0 | -123.4 | 65.0 | 70.2 | | ||
| + | | -0.21 | -0.02 | -75.4 | -75.4 | 70.2 | -128.6 | 70.2 | 75.4 | | ||
| + | | -0.12 | -0.01 | -80.0 | -80.0 | 74.8 | -133.2 | 74.8 | 80.0 | | ||
| + | | -0.06 | -0.01 | -86.0 | -86.0 | 80.8 | -139.2 | 80.8 | 86.0 | | ||
| + | |||
| + | {{:adc2:simulations:fsim_diff_log.png|}} | ||
| + | |||
| + | **remark** : 1%@20Mhz@16kp = 12.7 Hz | ||
| + | |||
| + | **conclusion** : if we want to achive resonable measurement resutls for 10-bit ADC working @ 20 Mhz (and with 16k FFT len) input signal freq should not differ from ideal one more then ~1 Hz. | ||
| + | |||
| + | **conclusion 2 ** : reducing lenght of FFT (fbase is becoming larger) should relax this requirement (but also degrade precision of measurement) | ||
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