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参数资料
| 型号： | AD8331-EVAL |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| 中文描述： | 超低噪声的VGA前置放大器和可编程与房地产经纪人 |
| 文件页数： | 17/32页 |
| 文件大小： | 482K |
| 代理商： | AD8331-EVAL |
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AD8331/AD8332
THEORY OF OPERATION
OVERVIEW
The following discussion applies to all part numbers. Figure 56
and Figure 1 are functional block diagrams of the AD8331 and
AD8332, respectively.
Rev. C | Page 17 of 32
LNA
2
1
6
3
LMD
INH
COML
VPSL
10
GAIN
COMM
LNA
BIAS
(V
MID
)
VGA
G = –48dB to 0dB
+21dB
BIAS AND
INTERPOLATOR
20
4
5
7
8
17
19
18
V
MID
POST
12
CLAMP
INT
11
19
15
16
9
3.5dB/
15.5dB
ENBL
ENBV
RCLMP
VOH
VOL
MODE
LON LOP VIP VIN
VPOS
VCM
14
HILO
COMM
AD8331
0
Figure 56. Functional Block Diagram — AD8331
Each channel contains an LNA that provides user-adjustable
input impedance termination, a differential X-AMP VGA, and a
programmable gain postamplifier with adjustable output
voltage limiting. Figure 57 shows a simplified block diagram.
VOL
VOH
LNA
CLAMP*
–
+
INH
LMD
LOP
LON
HILO
VCM
PREAMPLIFIER
19dB
X-AMP VGA
POSTAMP
[(–48 to 0) + 21] dB
3.5dB/15.5dB
INTGAIN
GAIN
BIAS AND
INTERPOLATOR*
VIN
VIP
*SHARED BETWEEN CHANNELS
RCLMP
BIAS
(V
MID
)
V
MID
0
Figure 57. Simplified Block Diagram
The linear-in-dB gain control interface is trimmed for slope and
absolute accuracy. The overall gain range is 48 dB, extending
from –4.5 dB to +43.5 dB or from +7.5 dB to +55.5 dB,
depending on the setting of the HILO pin. The slope of the gain
control interface is 50 dB/V, and the gain control range is 40 mV
to 1 V, leading to the following expressions for gain:
(
50
)
(
V
V
dB
dB
GAIN
GAIN
or
(
50
)
(
V
V
dB
dB
GAIN
GAIN
)
(
)
( )
1
,
5
.
6
LO
HILO
dB
–
=
×
=
)
(
)
( )
2
,
5
.
5
HI
HILO
dB
=
+
×
=
The gain characteristics are shown in Figure 58.
G
40
50
0
0.2
V
GAIN
(V)
0.6
0.4
30
10
0
20
–10
1.0
0.8
1.1
60
HILO = HI
HILO = LO
MODE = LO
MODE = HI
(WHERE AVAILABLE)
0
Figure 58. Gain Control Characteristics
When MODE is set high, (where available):
(
)
(
)
( )
3
=
,
5
.
45
+
×
50
–
=
)
(
LO
HILO
dB
V
V
dB
dB
GAIN
GAIN
or
V
GAIN
(
)
(
)
( )
4
=
,
5
.
57
+
×
50
–
=
)
(
HI
HILO
dB
V
dB
dB
GAIN
The LNA converts a single-ended input to a differential output
with a voltage gain of 19 dB. When only one output is used, the
gain is 13 dB. The inverting output is used for active input
impedance termination. Each of the LNA outputs is capacitively
coupled to a VGA input. The VGA consists of an attenuator
with a range of 48 dB followed by an amplifier with 21 dB of
gain, for a net gain range of –27 dB to +21 dB. The X-AMP
gain-interpolation technique results in low gain error and
uniform bandwidth, and differential signal paths minimize
distortion.
The final stage is a logic programmable amplifier with gains of
3.5 dB or 15.5 dB. The LO and HI gain modes are optimized
for 12-bit and 10-bit A/D converter applications, in terms of
output-referred noise and absolute gain range. Output voltage
limiting may be programmed by the user.
LOW NOISE AMPLIFIER (LNA)
Good noise performance relies on a proprietary ultralow noise
preamplifier at the beginning of the signal chain, which
minimizes the noise contribution in the following VGA. Active
impedance control optimizes noise performance for
applications that benefit from input matching.
相关PDF资料 |
PDF描述 |
|---|---|
| AD8331ARQ | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| AD8332 | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| AD8332-EVAL | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| AD8332ACP-REEL | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| AD8332ACP-REEL7 | Ultralow Noise VGAs with Preamplifier and Programmable RIN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8331-EVALZ | 功能描述:BOARD EVAL FOR AD8331 RoHS:是 类别:编程器，开发系统 >> 评估板 - 运算放大器 系列:X-AMP® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
| AD8331-EVALZ | 制造商:Analog Devices 功能描述:AD8331, VARIABLE GAIN AMPLIFIER, EVALUAT |
| AD8332 | 制造商:AD 制造商全称:Analog Devices 功能描述:Ultralow Noise VGAs with Preamplifier and Programmable RIN |
| AD8332ACP-R2 | 功能描述:IC VGA DUAL W/PREAMP LN 32-LFCSP RoHS:否 类别:集成电路 (IC) >> 线性 - 放大器 - 专用 系列:X-AMP® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:60 系列:- 类型:可变增益放大器 应用:CATV 安装类型:表面贴装 封装/外壳:20-WQFN 裸露焊盘 供应商设备封装:20-TQFN-EP（5x5） 包装:托盘 |
| AD8332ACP-REEL | 制造商:Analog Devices 功能描述:SP Amp Variable Gain Amp Dual 5.5V 32-Pin LFCSP EP T/R 制造商:Rochester Electronics LLC 功能描述: |
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