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| 型號： | EVAL-ADUC834QSZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 20/80頁 |
| 文件大?。?/td> | 0K |
| 描述： | KIT DEV QUICK START ADUC834 |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 系列： | QuickStart™ 套件 |
| 類型： | MCU |
| 適用于相關(guān)產(chǎn)品： | ADuC834 |
| 所含物品： | 評估板，線纜，電源，軟件和文檔 |
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REV. A
ADuC834
–27–
In operation, the analog signal sample is fed to the difference
amplifier along with the output of the feedback DAC. The
difference between these two signals is integrated and fed to the
comparator. The output of the comparator provides the input to
the feedback DAC so the system functions as a negative feedback
loop that tries to minimize the difference signal. The digital
data that represents the analog input voltage is contained in the
duty cycle of the pulse train appearing at the output of the com-
parator. This duty cycle data can be recovered as a data-word
using a subsequent digital filter stage. The sampling frequency of
the modulator loop is many times higher than the bandwidth
of the input signal. The integrator in the modulator shapes the
quantization noise (which results from the analog-to-digital
conversion) so that the noise is pushed toward one-half of the
modulator frequency.
Digital Filter
The output of the
-
modulator feeds directly into the digital
filter. The digital filter then band-limits the response to a fre-
quency significantly lower than one-half of the modulator frequency.
In this manner, the 1-bit output of the comparator is translated
into a band-limited, low noise output from the ADuC834 ADCs.
The ADuC834 filter is a low-pass, Sinc
3 or (SIN x/x)3 filter
whose primary function is to remove the quantization noise
introduced at the modulator. The cutoff frequency and decimated
output data rate of the filter are programmable via the SF (Sinc
Filter) SFR as described in Table VIII.
Figure 11 shows the frequency response of the ADC channel at
the default SF word of 69 dec or 45H, yielding an overall output
update rate of just under 20 Hz.
It should be noted that this frequency response allows frequency
components higher than the ADC Nyquist frequency to pass
through the ADC, in some cases without significant attenuation.
These components may, therefore, be aliased and appear
in-band after the sampling process.
It should also be noted that rejection of mains-related frequency
components, i.e., 50 Hz and 60 Hz, is seen to be at a level of
>65 dB at 50 Hz and >100 dB at 60 Hz. This confirms the data
sheet specifications for 50 Hz/60 Hz Normal Mode Rejection
(NMR) at a 20 Hz update rate.
020
30
50
70
8090
100
110
FREQUENCY – Hz
GAIN
–
dB
0
–20
–40
–70
–80
–90
–100
–110
–120
10
40
60
–10
–30
–60
–50
Figure 11. Filter Response, SF = 69 dec
The response of the filter, however, will change with SF word as
can be seen in Figure 12, which shows >90 dB NMR at 50 Hz
and >70 dB NMR at 60 Hz when SF = 255 dec.
020
30
50
7080
90
110
FREQUENCY – Hz
GAIN
–
dB
0
–20
–40
–70
–80
–90
–100
–110
–120
10
40
60
–10
–30
–60
–50
Figure 12. Filter Response, SF = 255 dec
Figures 13 and 14 show the NMR for 50 Hz and 60 Hz across
the full range of SF word, i.e., SF = 13 dec to SF = 255 dec.
10
50
70
110
150 170 190 210
SF – Decimal
GAIN
–
dB
0
–20
–40
–70
–80
–90
–100
–110
–120
30
90
130
–10
–30
–60
–50
230 250
Figure 13. 50 Hz Normal Mode Rejection vs. SF
10
50
70
110
150 170 190 210
SF – Decimal
GAIN
–
dB
0
–20
–40
–70
–80
–90
–100
–110
–120
30
90
130
–10
–30
–60
–50
230 250
Figure 14. 60 Hz Normal Mode Rejection vs. SF
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| EVAL-ADUC836QS | 制造商:Analog Devices 功能描述:MCU 8BIT 8052 CISC 62KB+4KB FLASH 3.6V 48LQFP - Bulk 制造商:Analog Devices 功能描述:KIT- ADUC836 DEV SYSTEM |
| EVAL-ADUC841QS | 制造商:AD 制造商全稱:Analog Devices 功能描述:MicroConverter 12-Bit ADCs and DACs with Embedded High Speed 62-kB Flash MCU |
| EVAL-ADUC841QSP2 | 制造商:AD 制造商全稱:Analog Devices 功能描述:MicroConverter 12-Bit ADCs and DACs with Embedded High Speed 62-kB Flash MCU |
| EVAL-ADUC841QSPZ | 功能描述:KIT DEV QUICK START ADUC841 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 通用嵌入式開發(fā)板和套件（MCU、DSP、FPGA、CPLD等） 系列:QuickStart™ PLUS 套件 標(biāo)準(zhǔn)包裝:1 系列:PICDEM™ 類型:MCU 適用于相關(guān)產(chǎn)品:PIC10F206，PIC16F690，PIC16F819 所含物品:板，線纜，元件，CD，PICkit 編程器 產(chǎn)品目錄頁面:659 (CN2011-ZH PDF) |
| EVAL-ADUC841QSPZ | 制造商:Analog Devices 功能描述:Silicon Manufacturer:Analog Devices C |
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