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参数资料
| 型号： | AD8138-EVAL |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | Low Distortion Differential ADC Driver |
| 中文描述： | 低失真差分ADC驱动器 |
| 文件页数： | 5/14页 |
| 文件大小： | 231K |
| 代理商： | AD8138-EVAL |
AD8138
–13–
REV. A
3 V OPERATION
The circuit in Figure 41 shows a simplified front end connection
for an AD8138 driving an AD9203, a 10-bit, 40 MSPS A/D
converter that is specified to work on a single +3 V supply. The
A/D works best when driven differentially to make the best use
of the signal swing available within the 3 V supply. The appro-
priate outputs of the AD8138 are connected to the appropriate
differential inputs of the AD9203 via a low-pass filter.
The AD8138 is configured for unity gain for a single-ended
input-to-differential output. The additional 23
at the input to
–IN is to balance the impedance of the 50
source and its 50
termination that drives the noninverting input.
The signal generator has ground-referenced, bipolar output, i.e.,
it can drive symmetrically above and below ground. Even
though the AD8138 has ground as its negative supply, it can
still function as a level-shifter with such an input signal.
The output common-mode is raised up to midsupply by the
voltage divider that biases VOCM. In this way, the AD8138 pro-
vides dc-coupling and level-shifting of a bipolar signal, without
inverting the input signal.
The low-pass filter between the AD8138 and the AD9203 pro-
vides filtering that helps to improve the signal-to-noise ratio.
Lower noise can be realized by lowering the pole frequency, but
the bandwidth of the circuit will be lowered.
The circuit was tested with a –0.5 dBFS signal at various fre-
quencies. Figure 42 shows a plot of the total harmonic distor-
tion (THD) vs. frequency at signal amplitudes of 1 V and 2 V
differential drive levels.
Figure 43 shows the signal to noise plus distortion (SINAD)
under the same conditions as above. For the smaller signal
swing, the AD8138 performance is quite good, but its perfor-
mance degrades when trying to swing too close to the supply
rails.
49.9
0.1 F
10k
523
499
10k
20pF
49.9
20pF
499
0.1 F
AINN
+3V
DRVDD
AVDD
AVSS DRVSS
AINP
0.1 F
DIGITAL
OUTPUTS
+3V
49.9
AD8138
+
AD9203
Figure 41. AD8138 Driving an AD9203, a 10-Bit, 40 MSPS
A/D Converter
FREQUENCY – MHz
–40
0
THD
–
dBc
5
101520
25
–45
–50
–55
–60
–65
–70
–75
–80
AD8138-2V
AD8138-1V
Figure 42. AD9203 THD @ –0.5 dBFS AD8138
FREQUENCY – MHz
65
0
SINAD
–
dBc
5
101520
25
63
61
59
57
55
53
51
45
49
47
AD8138-1V
AD8138-2V
Figure 43. AD9203 SINAD @ –0.5 dBFS AD8138
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相关代理商/技术参数 |
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| AD8139_07 | 制造商:AD 制造商全称:Analog Devices 功能描述:Low Noise, Rail-to-Rail, Differential ADC Driver |
| AD8139ACP | 制造商:Analog Devices 功能描述:ULTRA LOW NOISE FULLY DIFFERENTIAL ADC DRIVER - Bulk |
| AD8139ACP-EBZ | 功能描述:BOARD EVAL FOR AD8139ACP RoHS:是 类别:编程器，开发系统 >> 评估板 - 运算放大器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
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