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AD830JR 参数 Datasheet PDF下载

AD830JR图片预览
型号: AD830JR
PDF下载: 下载PDF文件 查看货源
内容描述: 高速视频差动放大器 [High Speed, Video Difference Amplifier]
分类和应用: 放大器
文件页数/大小: 16 页 / 336 K
品牌: ADI [ ADI ]
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AD830  
D iffer ential Line Receiver  
D iffer ence Am plifier with Gain > 1  
T he AD830 was specifically designed to perform as a differen-  
tial line receiver. T he circuit in Figure 33 shows how simple it is  
to configure the AD830 for this function. T he signal from sys-  
tem “A” is received differentially relative to A’s common, and  
that voltage is exactly reproduced relative to the common in sys-  
tem B. T he common-mode rejection versus frequency, shown in  
Figure 1, is excellent, typically 100 dB at low frequencies. T he  
high input impedance permits the AD830 to operate as a bridg-  
ing amplifier across low impedance terminations with negligible  
loading. T he differential gain and phase specifications are very  
good as shown in Figure 7 for 500 and Figure 10 for 150 .  
T he input and output common should be separated to achieve  
the full CMR performance of the AD830 as a differential ampli-  
fier. However, a common return path is necessary between sys-  
tems A and B.  
T he AD830 can provide instrumentation amplifier style differ-  
ential amplification at gains greater than 1. T he input signal is  
connected differentially and the gain is set via feedback resistors  
as shown in Figure 35. T he gain, G = (R2 + R1)/R2. T he AD830  
can provide either inverting or noninverting differential amplifi-  
cation. T he polarity of the gain is established by the polarity of  
the connection at the input. Feedback resistors R2 should gener-  
ally be R2 1 kto maintain closed-loop stability and also keep  
bias current induced offsets low. Highest CMRR and lowest dc  
offsets are preserved by including a compensating resistor in  
series with Pin 3. T he gain may be as high as 100.  
V
P
0.1µF  
AD830  
8
V
1
2
3
4
1
V
G
G
CM  
M
V
P
INPUT  
SIGNAL  
V
OUT  
0.1µF  
7
6
5
V
2
AD830  
V
8
1
A=1  
1
V
G
G
CM  
Z
M
CM  
INPUT  
SIGNAL  
R
R
2
1
V
OUT  
C
2
3
4
7
6
5
V
2
M
A=1  
0.1µF  
COMMON IN  
SYSTEM A  
Z
CM  
C
R1  
M
V
N
0.1µF  
R2  
V
N
V
= (V – V ) (1+R /R )  
1 2 1 2  
OUT  
V
= V – V  
1
2
COMMON IN  
SYSTEM  
OUT  
B
Figure 35. Gain of G Differential Am plifier, G > 1  
O ffsetting the O utput with Gain  
Figure 33. Differential Line Receiver  
Wide Range Level Shifter  
Some applications, such as A/D drivers, require that the signal  
be amplified and also offset, typically to accommodate the input  
range of the device. T he AD830 can offset the output signal  
very simply through Pin 3 even with gain > 1. T he voltage ap-  
plied to Pin 3 must be attenuated by an appropriate factor so  
that V3 ϫ G = desired offset. In Figure 36, a resistive divider  
from a voltage reference is used to produce the attenuated offset  
voltage.  
T he wide common-mode range and accuracy of the AD830 al-  
lows easy level shifting of differential signals referred to an input  
common-mode voltage to any new voltage defined at the out-  
put. T he inputs may be referenced to levels as high as 10 V at  
the inputs with a ±2 V swing about 10 V. In the circuit of Fig-  
ure 34, the output voltage, VOUT , is defined by the simple equa-  
tion shown below. T he excellent linearity and low distortion are  
preserved over the full input and output common-mode range.  
T he voltage sources need not be of low impedance, since the  
high input resistance and modest input bias current of the  
AD830 V-to-I converters permit the use of resistive voltage di-  
viders as reference voltages.  
V
P
0.1µF  
AD830  
V
1
8
7
1
V
G
CM  
M
INPUT  
SIGNAL  
V
OUT  
2
3
4
V
2
A=1  
V
P
Z
CM  
R
R
2
1
0.1µF  
6
5
AD830  
C
G
V
1
8
7
6
5
1
M
G
G
M
INPUT  
SIGNAL  
0.1µF  
V
OUT  
2
3
4
V
2
V
REF  
R
A=1  
1
INPUT  
COMMON  
V
N
R
C
2
M
R
3
0.1µF  
V
3
V
= (V – V ) (1+R /R )  
1 2 1 2  
OUT  
R
4
V
N
V
3
V
= V – V + V  
1 2 3  
OUT  
OUTPUT  
Figure 36. Offsetting the Output with Differential Gain > 1  
COMMON  
Figure 34. Differential Am plification with Level Shifting  
REV. A  
–13–