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參數資料
| 型號： | AD7854 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 12-Bit Sampling ADC(單電源,200kSPS 12位采樣A/D轉換器) |
| 中文描述： | 12位采樣ADC（單電源，速度高達200ksps的12位采樣的A / D轉換器） |
| 文件頁數： | 6/28頁 |
| 文件大小： | 268K |
| 代理商： | AD7854 |
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AD7854/AD7854L
–6–
REV. 0
T otal Harmonic Distortion
T otal harmonic distortion (T HD) is the ratio of the rms sum of
harmonics to the fundamental. For the AD7854/AD7854L, it is
defined as:
THD
(
dB
)
=
20log
(
V
2
2
+
V
3
2
+
V
4
2
+
V
5
2
+
V
6
2
)
V
1
where
V
1
is the rms amplitude of the fundamental and
V
2
,
V
3
,
V
4
,
V
5
and
V
6
are the rms amplitudes of the second through the
sixth harmonics.
Peak Harmonic or Spurious Noise
Peak harmonic or spurious noise is defined as the ratio of the
rms value of the next largest component in the ADC output
spectrum (up to f
S
/2 and excluding dc) to the rms value of the
fundamental. Normally, the value of this specification is deter-
mined by the largest harmonic in the spectrum, but for ADCs
where the harmonics are buried in the noise floor, it will be a
noise peak.
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities will create distortion
products at sum and difference frequencies of mfa
±
nfb where
m, n = 0, 1, 2, 3, etc. Intermodulation distortion terms are
those for which neither m nor n are equal to zero. For example,
the second order terms include (fa + fb) and (fa – fb), while the
third order terms include (2fa + fb), (2fa – fb), (fa + 2fb) and
(fa – 2fb).
T esting is performed using the CCIF standard where two input
frequencies near the top end of the input bandwidth are used. In
this case, the second order terms are usually distanced in fre-
quency from the original sine waves while the third order terms
are usually at a frequency close to the input frequencies. As a
result, the second and third order terms are specified separately.
T he calculation of the intermodulation distortion is as per the
T HD specification where it is the ratio of the rms sum of the
individual distortion products to the rms amplitude of the sum
of the fundamentals expressed in dBs.
T E RMINOLOGY
Integral Nonlinearity
T his is the maximum deviation from a straight line passing
through the endpoints of the ADC transfer function. T he end-
points of the transfer function are zero scale, a point 1/2 LSB
below the first code transition, and full scale, a point 1/2 LSB
above the last code transition.
Differential Nonlinearity
T his is the difference between the measured and the ideal 1 LSB
change between any two adjacent codes in the ADC.
Unipolar Offset E rror
T his is the deviation of the first code transition (00 . . . 000 to
00 . . . 001) from the ideal AIN(+) voltage (AIN(–) + 1/2 LSB)
when operating in the unipolar mode.
Unipolar Gain E rror
T his is the deviation of the last code transition (111 . . . 110 to
111 . . . 111) from the ideal, i.e., AIN(–) +V
REF
/2 – 1.5 LSB, af-
ter the unipolar offset error has been adjusted out.
Bipolar Positive Full-Scale E rror
T his applies to the bipolar modes only and is the deviation of the
last code transition from the ideal AIN(+) voltage. For bipolar
mode, the ideal AIN(+) voltage is (AIN(–) +V
REF
/2 – 1.5 LSB).
Negative Full-Scale E rror
T his applies to the bipolar mode only and is the deviation of the
first code transition (10 . . . 000 to 10 . . . 001) from the ideal
AIN(+) voltage (AIN(–) – V
REF
/2 + 0.5 LSB).
Bipolar Zero E rror
T his is the deviation of the midscale transition (all 0s to all 1s)
from the ideal AIN(+) voltage (AIN(–) – 1/2 LSB).
T rack/Hold Acquisition T ime
T he track/hold amplifier returns into track mode and the end of
conversion. T rack/Hold acquisition time is the time required for
the output of the track/hold amplifier to reach its final value,
within
±
1/2 LSB, after the end of conversion.
Signal to (Noise + Distortion) Ratio
T his is the measured ratio of signal to (noise + distortion) at the
output of the A/D converter. T he signal is the rms amplitude of
the fundamental. Noise is the sum of all nonfundamental sig-
nals up to half the sampling frequency (f
S
/2), excluding dc. T he
ratio is dependent on the number of quantization levels in the
digitization process; the more levels, the smaller the quantiza-
tion noise. T he theoretical signal to (noise + distortion) ratio for
an ideal N-bit converter with a sine wave input is given by:
Signal to
(
Noise + Distortion
)
=
(6.02
N +
1.76)
dB
T hus for a 12-bit converter, this is 74 dB.
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| AD7858LARS | 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADC |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD7854AD | 制造商:Analog Devices 功能描述: |
| AD7854AQ | 功能描述:IC ADC 12BIT PARALLEL LP 28-CDIP RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1,000 系列:- 位數:12 采樣率（每秒）:300k 數據接口:并聯 轉換器數目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數目和類型:1 個單端，單極；1 個單端，雙極 |
| AD7854AR | 功能描述:IC ADC 12BIT PARALLEL LP 28-SOIC RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1,000 系列:- 位數:12 采樣率（每秒）:300k 數據接口:并聯 轉換器數目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數目和類型:1 個單端，單極；1 個單端，雙極 |
| AD7854AR-REEL | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 12-bit Parallel 28-Pin SOIC W T/R 制造商:Analog Devices 功能描述:ADC SGL SAR 200KSPS 12-BIT PARALLEL 28SOIC W - Tape and Reel |
| AD7854ARS | 功能描述:IC ADC 12BIT PARALLEL LP 28-SSOP RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1,000 系列:- 位數:12 采樣率（每秒）:300k 數據接口:并聯 轉換器數目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數目和類型:1 個單端，單極；1 個單端，雙極 |
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