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參數資料
| 型號： | AD8391 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 運動控制電子 |
| 英文描述： | xDSL Line Driver 3 V to 12 V with Power-Down |
| 中文描述： | xDSL線路驅動，3V至12V，并有電源關斷功能 |
| 文件頁數： | 10/20頁 |
| 文件大?。?/td> | 278K |
| 代理商： | AD8391 |
REV. 0
AD8391
–10–
V
O
BIAS
V
N
V
P
Figure 3. Simplified Schematic
G = 1
I
T
= I
IN
C
T
R
T
I
IN
V
OUT
R
G
R
F
R
IN
+
V
IN
–
V
O
+
–
Figure 4. Model of Current Feedback Amplifier
Feedback Resistor Selection
In current feedback amplifiers, selection of the feedback and
gain resistors will impact distortion, bandwidth,
noise, and gain
flatness. Care should be exercised in the selection
of these resistors
so that the optimum performance is achieved. Table I shows the
recommended resistor values for use in a
variety of gain settings for
the test circuits in TPC 1 and TPC 19.
These values are only
intended to be a starting point when designing for any application.
Table I. Resistor Selection Guide
Gain
R
F
( )
909
909
909
909
909
R
G
( )
909
453
303
227
178
–
1
–
2
–
3
–
4
–
5
GENERAL INFORMATION
Theory of Operation
The AD8391 is a dual current feedback amplifier with high
output current capability. It is fabricated on Analog Devices
’
proprietary eXtra Fast Complementary Bipolar Process (XFCB)
that
enables the construction of PNP and NPN transistors with f
T
’
s
greater than 3 GHz. The process uses dielectrically isolated
transistors to eliminate the parasitic and latch-up problems caused
by junction
isolation. These features enable the construction of
high-frequency,
low-distortion amplifiers.
The AD8391 has a unique pin out. The two noninverting inputs
of the amplifier are connected to the V
MID
pin, which is internally
biased by two 5 k
resistors forming a voltage divider between
+V
S
and
–
V
S
. V
MID
is accessible through Pin 7. There is also a
10 pF internal capacitor from V
MID
to
–
V
S.
The two inverting pins
are available at Pin 1 and Pin 8, allowing the gain of the amplifiers to
be set with external resistors
. See the front page for a connection
diagram of the AD8391.
A simplified schematic of an amplifier is shown in Figure 3. Emitter
followers buffer the positive input, V
P
, to provide low-input current
and current noise. The low-impedance current feedback summing
junction is at the negative input, V
N
. The output stage is another
high-gain amplifier used as an integrator to provide frequency com-
pensation. The complementary common-emitter output provides the
extended output swing.
A current feedback amplifier
’
s bandwidth and distortion
performance are relatively insensitive to its closed-loop signal gain,
which is a distinct advantage over a voltage-feedback architecture.
Figure 4 shows a simplified model of a current feedback amplifier.
The feedback signal is an error current that flows into the inverting
node. R
IN
is inversely proportional to the transconductance of
the amplifier
’
s input stage, g
mi
. Circuit analysis of the pictured
follower with gain circuit yields:
V
V
G
Tz s
+
Tz s
R
G
R
OUT
IN
F
IN
=
×
+
×
where:
G
R
R
F
G
= +
1
Tz s
R
sC
R
F
T
T
=
+
1
(
)
R
g
IN
mi
=
1
125
Recognizing that G
×
R
IN
<<
R
F
, and that the
–
3 dB point is set
when
Tz(s)
=
R
F
, one can see that the amplifier
’
s bandwidth
depends primarily on the feedback resistor. There is a value of
R
F
below which the amplifier will be unstable, as the
amplifier
will have additional poles that will contribute excess phase shift.
The optimum value for R
F
depends on the gain and the amount
of peaking tolerable in the application. For more
information
about current feedback amplifiers, see ADI
’
s High-Speed Design
Techniques at www.analog.com/technology/amplifiersLinear/
designTools/evaluationBoards/pdf/1.pdf
.
相關PDF資料 |
PDF描述 |
|---|---|
| AD8391AR | xDSL Line Driver 3 V to 12 V with Power-Down |
| AD8391AR-EVAL | xDSL Line Driver 3 V to 12 V with Power-Down |
| AD8391AR-REEL | xDSL Line Driver 3 V to 12 V with Power-Down |
| AD8391AR-REEL7 | xDSL Line Driver 3 V to 12 V with Power-Down |
| AD8392ARE-REEL | Low Power, High Output Current, Quad Op Amp, Dual-Channel ADSL/ADSL2+ Line Driver |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8391AR | 制造商:Analog Devices 功能描述:SP Amp Line Driver Amp Dual ±6V/12V 8-Pin SOIC N Tube 制造商:Rochester Electronics LLC 功能描述:SOIC XDSL LINE DRIVE AMPLIFIERS W/PWR DN - Bulk |
| AD8391AR-EVAL | 制造商:Analog Devices 功能描述:Evaluation Board For XDSL Line Driver 3 V To 12 V With Power-Down |
| AD8391AR-REEL | 功能描述:IC XDSL LINE DVR W/PWR DN 8-SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:50 系列:- 類型:收發器 驅動器/接收器數:1/1 規程:RS422，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應商設備封裝:8-PDIP 包裝:管件 產品目錄頁面:1402 (CN2011-ZH PDF) |
| AD8391AR-REEL7 | 功能描述:IC XDSL LINE DVR W/PWR DN 8-SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發器 系列:- 標準包裝:1,140 系列:AU 類型:收發器 驅動器/接收器數:1/1 規程:CAN 電源電壓:5.3 V ~ 27 V 安裝類型:表面貼裝 封裝/外殼:14-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:14-SO 包裝:管件 其它名稱:935267940512AU5790D14AU5790D14-ND |
| AD8391ARZ | 制造商:Analog Devices 功能描述:SP Amp Line Driver Amp Dual ±6V/12V 8-Pin SOIC N Tube |
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