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AD8055ARZ 参数 Datasheet PDF下载

AD8055ARZ图片预览
型号: AD8055ARZ
PDF下载: 下载PDF文件 查看货源
内容描述: 低成本, 300 MHz电压反馈放大器 [Low Cost, 300 MHz Voltage Feedback Amplifiers]
分类和应用: 放大器
文件页数/大小: 16 页 / 302 K
品牌: ADI [ ADI ]
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AD8055/AD8056  
APPLICATIONS  
Between these points, a feedback resistor can be used to close  
the loop. As in the case of a conventional op amp inverting gain  
stage, an input resistor is added to vary the gain.  
FOUR-LINE VIDEO DRIVER  
The AD8055 is a useful low cost circuit for driving up to four  
video lines. For such an application, the amplifier is configured  
for a noninverting gain of 2, as shown in Figure 36. The input  
video source is terminated in 75 ꢀ and is applied to the high  
impedance noninverting input.  
The gain of this circuit from the input to AMP1 output is RF/RI,  
while the gain to the output of AMP2 is −RF /RI. The circuit  
therefore creates a balanced differential output signal from a  
single-ended input. The advantage of this circuit is that the gain  
can be changed by changing a single resistor, while still  
maintaining the balanced differential outputs.  
Each output cable is connected to the op amp output via a 75 ꢀ  
series back termination resistor for proper cable termination.  
The terminating resistors at the other ends of the lines divide  
the output signal by 2, which is compensated for by the gain of 2  
of the op amp stage.  
R
F
402  
+5V  
For a single load, the differential gain error of this circuit was  
measured as 0.01%, with a differential phase error of 0.02°. The  
two load measurements were 0.02% and 0.03°, respectively. For  
four loads, the differential gain error is 0.02%, while the  
differential phase increases to 0.1°.  
0.1µF  
1
10µF  
R
402Ω  
I
8
3
2
V
IN  
49.9Ω  
+V  
AMP1  
OUT  
402Ω  
402Ω  
75  
V
OUT1  
+5V  
402Ω  
402Ω  
75Ω  
402Ω  
AD8056  
75Ω  
0.1µF  
10µF  
10µF  
V
402Ω  
75Ω  
OUT2  
2
7
75Ω  
6
AD8055  
6
5
V
3
4
IN  
49.9Ω  
75Ω  
75Ω  
7
–V  
OUT  
AMP2  
4
V
V
OUT3  
0.1µF  
75Ω  
75Ω  
75Ω  
0.1µF  
10µF  
–5V  
–5V  
OUT4  
Figure 37. Single-Ended-to-Differential Line Driver  
Figure 36. Four-Line Video Driver  
LOW NOISE, LOW POWER PREAMP  
The AD8055 makes a good, low cost, low noise, low power  
preamp. A gain-of-10 preamp can be made with a feedback  
resistor of 909 ꢀ and a gain resistor of 100 ꢀ, as shown in  
Figure 38. The circuit has a −3 dB bandwidth of 20 MHz.  
SINGLE-ENDED-TO-DIFFERENTIAL LINE DRIVER  
Creating differential signals from single-ended signals is  
required for driving balanced, twisted pair cables, differential  
input ADCs, and other applications that require differential  
signals. This can be accomplished by using an inverting and a  
noninverting amplifier stage to create the complementary  
signals.  
909  
+5V  
+
10µF  
0.1µF  
6
100Ω  
2
3
7
The circuit shown in Figure 37 shows how an AD8056 can be  
used to make a single-ended-to-differential converter that offers  
some advantages over the architecture previously mentioned.  
Each op amp is configured for unity gain by the feedback  
resistors from the outputs to the inverting inputs. In addition,  
each output drives the opposite op amp with a gain of −1 by  
means of the crossed resistors. The result of this is that the  
outputs are complementary and there is high gain in the overall  
configuration.  
V
AD8055  
OUT  
4
R
S
0.1µF  
10µF  
–5V  
Figure 38. Low Noise, Low Power Preamp with G = +10 and BW = 20 MHz  
With a low source resistance (< approximately 100 ꢀ), the  
major contributors to the input-referred noise of this circuit are  
the input voltage noise of the amplifier and the noise of the  
100 Ω resistor. These are 6 nV/√Hz and 1.2 nV/√Hz, respectively.  
These values yield a total input referred noise of 6.1 nV/√Hz.  
Feedback techniques similar to a conventional op amp are used  
to control the gain of the circuit. From the noninverting input  
of AMP1 to the output of AMP2 is an inverting gain.  
Rev. J | Page 12 of 16