- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄375266 > ADS807E 12-Bit, 53MHz Sampling ANALOG-TO-DIGITAL CONVERTER PDF資料下載
參數(shù)資料
| 型號： | ADS807E |
| 英文描述： | 12-Bit, 53MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 12位，53MHz采樣模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 10/15頁 |
| 文件大?。?/td> | 225K |
| 代理商： | ADS807E |
10
ADS807
will improve the SNR performance, but depending on the
signal source, large resistor values may be detrimental to
achieving good harmonic distortion. In any case, optimizing
the R-C values for the specific application is encouraged.
Transformer Coupled, Single-Ended to Differential
Configuration
If the application requires a signal conversion from a single-
ended source to drive the ADS807 differentially, an RF
transformer might be a good solution. The selected trans-
former must have a center tap in order to apply the common-
mode DC voltage necessary to bias the converter inputs. AC
grounding the center tap will generate the differential signal
swing across the secondary winding. Consider a step-up
transformer to take advantage of a signal amplification
without the introduction of another noise source. Further-
more, the reduced signal swing from the source may lead to
improved distortion performance.
The differential input configuration provides a noticeable
advantage of achieving good SFDR over a wide range of
input frequencies. In this mode, both inputs of the ADS807
see matched impedances. Figure 1 shows the schematic for
the suggested transformer coupled interface circuit. The
component values of the R-C low-pass may be optimized
depending on the desired roll-off frequency. The resistor
across the secondary side (R
T
) should be calculated using
the equation R
T
= n
2
x R
G
to match the source impedance
(R
G
) for good power transfer and VSWR.
The circuit example of Figure 1 shows the voltage feedback
amplifier OPA680 driving the RF transformer, which con-
verts the single-ended signal into a differential. The OPA680
can be employed for either single or dual supply operation.
For details on how to optimize its frequency response, refer
to the OPA680 data sheet. With the 49.9
series output
resistor, the amplifier emulates a 50
source (R
G
). Any DC
content of the signal can be easily blocked by a capacitor
(0.1
μ
F) and to also to avoid DC loading of the op amp’s
output stage.
AC-Coupled, Single-Ended to Differential Interface
with Dual-Supply Op Amps
Communications applications, in particular, demand a very
high dynamic range and low levels of intermodulation
distortion but, usually allow the input signal to be AC-
coupled into the A/D converter. Appropriate driver amplifi-
ers need to be selected to maintain the excellent distortion
performance of the ADS807. Often, these op amps deliver
the lowest distortion with a small, ground centered signal
swing that requires dual power supplies. Because of the AC-
coupling, this requirement can be easily accomplished and
the needed level shifting of the input signal can be imple-
mented without affecting the driver circuit.
Figure 2 shows an example of such an interface circuit
specifically designed to maximize the dynamic performance.
The voltage feedback amplifier, OPA642, maintains an
excellent distortion performance for input frequencies of up
to 15MHz. The two amplifiers (A1, A2) are configured as an
inverting and noninverting gain stage to convert the input
signal from single-ended to differential. The nominal gain
for this stage is set to +2V/V. The outputs of the OPA642s
are AC-coupled to the converter’s differential inputs. This
will keep the distortion performance at its best since the
signal range stays within the linear region of the op amp and
sufficient headroom to the supply rails can be maintained.
Four resistors located between the top (REFT) and bottom
(REFB) reference shift the input signal to a common-mode
voltage of approximately +2.5V.
The interface circuit of Figure 2 can be modified to extend
the bandwidth to approximately 25MHz by replacing the
OPA642 with its decompensated version, the OPA643. The
OPA643 provides the necessary slew rate for a low distor-
tion front end to the ADS807. With a minimum gain
stability of +3, the gain resistors have to be modified, as well
as optimizing the series resistor and shunt capacitance at
each of the converter inputs.
FIGURE 1. Converting a Single-Ended Input Signal into a Differential Signal Using a RF-Transformer.
V
IN
IN
IN
CM
+2.5V
24.9
24.9
47pF
R
T
47pF
10μF
0.1μF
1:n
0.1μF
R
G
R
2
R
1
OPA680
49.9
ADS807E
+
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADS808 | 12-Bit, 70MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| ADS809 | 12-Bit, 80MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| ADS820 | 10-Bit, 20MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| ADS820E | 10-Bit, 20MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| ADS820U | 10-Bit, 20MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS807E/1K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 53 MSPS SE/Diff imputs 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 |
| ADS807E/1KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 53 MSPS SE/Diff imputs 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 |
| ADS807EG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 53 MSPS SE/Diff imputs 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 |
| ADS808 | 制造商:BB 制造商全稱:BB 功能描述:12-Bit, 70MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| 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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。