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參數(shù)資料
| 型號： | ADS808 |
| 英文描述： | 12-Bit, 70MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 12位，70MHz的采樣模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 11/19頁 |
| 文件大?。?/td> | 364K |
| 代理商： | ADS808 |
ADS808
SBAS179C
11
www.ti.com
attenuate some of the wideband noise. The actual compo-
nent values would need to be tuned for the individual appli-
cation requirements. As a guideline, resistor values are
typically in the range of 10
to 100
, capacitors in the range
of 10pF to 200pF. In any case, the R
IN
and C
IN
values should
have a low tolerance. This will ensure that the ADS808 sees
closely matched source impedances.
AC-Coupled, Differential Interface with Gain
The interface circuit example presented in Figure 6 employs
two OPA685s, (current-feedback op amps), optimized for
gains of 8V/V or higher. The input transformer (T1) converts
the single-ended input signal to a differential signal required
at the amplifier
’
s inverting inputs, that are tuned to provide a
50
impedance match to an assumed 50
source. To
achieve the 50
input match at the primary of the 1:2
transformer, the secondary input must see a 200
load
impedance. Both amplifiers are configured for the inverting
mode resulting in close gain and phase matching of the
differential signal. This technique, along with a highly sym-
metrical layout, is instrumental in achieving a substantial
reduction of the 2nd-harmonic, while retaining excellent 3rd-
order performance. A common-mode voltage (V
CM
) is ap-
plied to the noninverting inputs of the OPA685. Additional
series of 43.2
resistors isolate the output of the op amps
from the capacitive load presented by the 22pF capacitors
and the input capacitance of the ADS808. This 43.2
/22pF
combination sets a pole at approximately 167MHz and rolls
off some of the wideband noise.
REFERENCE
REFERENCE OPERATION
Integrated into the ADS808 is a bandgap reference circuit
including some logic that provides a +0.5V, +0.75V, or +1V
reference output by selecting the corresponding pin-strap
configuration. Table I gives a complete overview of the
possible reference options and pin configurations.
+5V
–
5V
OPA685
22pF
22pF
+5V
–
5V
600
OPA685
T1
1:2
50
Source
V
I
Noise
Figure
11.8dB
V
CM
V
CM
600
100
100
43.2
Power-supply decoupling
not shown.
43.2
V
O
A/D Converter Input
V
O
V
I
= 12V/V (21.6dB)
DIS
DIS
FIGURE 6. Wideband Differential A/D Converter Driver.
DESIRED FULL-SCALE RANGE,
FSR (Differential)
CONNECT SEL1
(Pin 33)
CONNECT SEL2
(Pin 32)
VOLTAGE AT V
REF
(Pin 34)
VOLTAGE AT REFT
(Pin 41)
VOLTAGE AT REFB
(Pin 39)
2Vp-p (+10dBm)
1.5Vp-p (+7.5dBm)
1Vp-p
External Reference
GND
GND
V
REF
—
GND
+V
S
GND
—
+1.0V
+0.75V
+0.5V
> +3.5V
+3V
+2V
+2.875V
+2.75V
+2.75V to +4.5V
+2.125V
+2.25V
+0.5V to +2.25V
TABLE I. Reference Pin Configurations and Corresponding Voltage on the Reference Pins.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS808Y/250 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 70MHz Sampling ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS808Y/250G4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 70MHz Sampling ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS808Y/2K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 70MHz Sampling ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS808Y/2KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 70MHz Sampling ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS809 | 制造商:BB 制造商全稱:BB 功能描述:12-Bit, 80MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
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