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參數(shù)資料
| 型號： | AD7863 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Simultaneous Sampling Dual 175 kSPS 14-Bit ADC(同時采樣175kSPS14位雙A/D轉(zhuǎn)換器) |
| 中文描述： | 雙同步采樣175 kSPS的14位ADC（同時采樣175kSPS14位雙的A / D轉(zhuǎn)換器） |
| 文件頁數(shù)： | 12/18頁 |
| 文件大?。?/td> | 291K |
| 代理商： | AD7863 |
AD7863
–12–
REV. 0
AD7863 DYNAMIC SPECIFICATIONS
The AD7863 is specified and tested for dynamic performance
specifications as well as traditional dc specifications such as
Integral and Differential Nonlinearity. These ac specifications
are required for the signal processing applications such as
phased array sonar, adaptive filters and spectrum analysis.
These applications require information on the ADC’s effect on
the spectral content of the input signal. Hence, the parameters
for which the AD7863 is specified include SNR, harmonic dis-
tortion, intermodulation distortion and peak harmonics. These
terms are discussed in more detail in the following sections.
Signal-to-Noise Ratio (SNR)
SNR is the measured signal to noise ratio at the output of the
ADC. The signal is the rms magnitude of the fundamental.
Noise is the rms sum of all the nonfundamental signals up to
half the sampling frequency (f
S
/2), excluding dc. SNR is depen-
dent upon the number of quantization levels used in the digiti-
zation process; the more levels, the smaller the quantization
noise. The theoretical signal to noise ratio for a sine wave input
is given by
SNR
= (6.02
N
+ 1.76)
dB
where
N
is the number of bits.
Thus for an ideal 14-bit converter, SNR = 86.04 dB.
Figure 7 shows a histogram plot for 8,192 conversions of a dc
input using the AD7863 with 5 V supply. The analog input was
set at the center of a code transition. It can be seen that the
codes appear mainly in the one output bin, indicating very good
noise performance from the ADC.
(1)
CODE
8000
746
C
7000
6000
5000
4000
3000
2000
1000
0
747
748
749
750
751
752
753
754
755
Figure 7. Histogram of 8,192 Conversions of a DC Input
The output spectrum from the ADC is evaluated by applying a
sine wave signal of very low distortion to the V
AX/BX
input,
which is sampled at a 175 kHz sampling rate. A Fast Fourier
Transform (FFT) plot is generated from which the SNR data
can be obtained. Figure 8 shows a typical 8,192 point FFT plot
of the AD7863 with an input signal of 10 kHz and a sampling
frequency of 175 kHz. The SNR obtained from this graph is
–80.72 dB. It should be noted that the harmonics are taken into
account when calculating the SNR.
FREQUENCY – kHz
0
–130
10
d
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
20
30
40
50
60
70
80
90
F
SAMPLE
= 175kHz
F
SNR = +80.72dB
THD = –92.96dB
–140
–150
Figure 8. AD7863 FFT Plot
Effective Number of Bits
The formula given in Equation 1 relates the SNR to the number
of bits. Rewriting the formula, as in Equation 2, it is possible to
obtain a measure of performance expressed in effective number
of bits (N).
N
=
SNR
–1.76
6.02
(2)
The effective number of bits for a device can be calculated di-
rectly from its measured SNR.
Figure 9 shows a typical plot of effective number of bits versus
frequency for an AD7863-2 with a sampling frequency of
175 kHz. The effective number of bits typically falls between
13.11 and 11.05 corresponding to SNR figures of +80.68 dB
and +68.28 dB.
FREQUENCY – kHz
14.0
0
1000
200
E
400
600
800
13.5
13.0
12.5
12.0
11.5
11.0
10.5
10.0
Figure 9. Effective Numbers of Bits vs. Frequency
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7863AR-10 | 功能描述:IC ADC 14BIT DUAL 2CH 28-SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個單端，雙極 |
| AD7863AR-10REEL | 功能描述:IC ADC 14BIT DUAL 2CH 28-SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個單端，雙極 |
| AD7863AR-10REEL7 | 制造商:Analog Devices 功能描述:ADC Dual SAR 175ksps 14-bit Parallel 28-Pin SOIC W T/R |
| AD7863AR-2 | 功能描述:IC ADC 14BIT DUAL 2CH 28-SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 位數(shù):12 采樣率（每秒）:3M 數(shù)據(jù)接口:- 轉(zhuǎn)換器數(shù)目:- 功率耗散（最大）:- 電壓電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應(yīng)商設(shè)備封裝:SOT-23-6 包裝:帶卷 (TR) 輸入數(shù)目和類型:- |
| AD7863AR-2REEL | 制造商:Analog Devices 功能描述:ADC Dual SAR 175ksps 14-bit Parallel 28-Pin SOIC W T/R |
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