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參數資料
| 型號： | AD8133ACPZ-REEL7 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 通用總線功能 |
| 英文描述： | Triple Differential Driver With Output Pull-Down |
| 中文描述： | TRIPLE LINE DRIVER, QCC24 |
| 封裝： | 4 X 4 MM, LEAD FREE, MO-220VGGD-2, LFCSP-24 |
| 文件頁數： | 12/16頁 |
| 文件大小： | 479K |
| 代理商： | AD8133ACPZ-REEL7 |
AD8133
THEORY OF OPERATION
Each differential driver in the AD8133 differs from a conven-
tional op amp in that it has two outputs whose voltages move in
opposite directions. Like an op amp, it relies on high open-loop
gain and negative feedback to force these outputs to the desired
voltages. The AD8133 drivers make it easy to perform single-
ended-to-differential conversion, common-mode level shifting,
and amplification of differential signals.
Rev. 0 | Page 12 of 16
Previous differential drivers, both discrete and integrated
designs, have been based on using two independent amplifiers
and two independent feedback loops, one to control each of the
outputs. When these circuits are driven from a single-ended
source, the resulting outputs are typically not well balanced.
Achieving a balanced output has typically required exceptional
matching of the amplifiers and feedback networks.
DC common-mode level shifting has also been difficult with
previous differential drivers. Level shifting has required the use
of a third amplifier and feedback loop to control the output
common-mode level. Sometimes, the third amplifier has also
been used to attempt to correct an inherently unbalanced
circuit. Excellent performance over a wide frequency range has
proven difficult with this approach.
Each of the AD8133 drivers uses two feedback loops to
separately control the differential and common-mode output
voltages. The differential feedback, set by the internal resistors,
controls only the differential output voltage. The internal
common-mode feedback loop controls only the common-mode
output voltage. This architecture makes it easy to arbitrarily set
the output common-mode level by simply applying a voltage to
the V
OCM
input. The output common-mode voltage is forced, by
internal common-mode feedback, to equal the voltage applied to
the V
OCM
input, without affecting the differential output voltage.
The AD8133 architecture results in outputs that are highly
balanced over a wide frequency range without requiring exter-
nal components or adjustments. The common-mode feedback
loop forces the signal component of the output common-mode
voltage to be zeroed. The result is nearly perfectly balanced dif-
ferential outputs of identical amplitude that are exactly 180°
apart in phase.
DEFINITION OF TERMS
Differential Voltage
Differential voltage refers to the difference between two node
voltages that are balanced with respect to each other. For exam-
ple, in Figure 34 the output differential voltage (or equivalently
output differential mode voltage) is defined as
(
ON
OP
dm
OUT
V
V
V
=
,
)
Common-mode voltage refers to the average of two node volt-
ages with respect to a common reference. The output common-
mode voltage is defined as
2
)
(
,
ON
OP
cm
OUT
V
V
V
+
=
Output Balance
Output balance is a measure of how well the differential output
signals are matched in amplitude and how close they are to
exactly 180° apart in phase. Balance is most easily determined
by placing a well-matched resistor divider between the differen-
tial output voltage nodes and comparing the magnitude of the
signal at the divider’s midpoint with the magnitude of the d
ferential signal. By this definition, output balance error is the
magnitude of the change in output common-mode voltage
divided by the magnitude of the change in output differential-
mode voltage in response to a differential input signal.
if-
dm
OUT
V
cm
OUT
V
Error
Balance
Output
,
,
=
ANALYZING AN APPLICATION CIRCUIT
The AD8133 uses high open-loop gain and negative feedback to
force its differential and common-mode output voltages to
minimize the differential and common-mode input error
voltages. The differential input error voltage is defined as the
voltage between the differential inputs labeled V
AP
and V
AN
in
Figure 34. For most purposes, this voltage can be assumed to be
zero. Similarly, the difference between the actual output
common-mode voltage and the voltage applied to V
OCM
can also
be assumed to be zero. Starting from these two assumptions, any
application circuit can be analyzed.
CLOSED-LOOP GAIN
The differential mode gain of the circuit in Figure 34 can be
described by the following equation.
2
=
=
G
F
IN,dm
V
OUT,dm
V
R
R
where R
F
= 1.5 k and R
G
= 750 nominally.
R
G
V
AP
V
AN
V
IP
IN
+
V
IN, dm
–
V
OCM
V
ON
V
OUT, dm
V
OP
R
G
R
F
R
F
R
L, dm
0
Figure 34.
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相關代理商/技術參數 |
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|---|---|
| AD8134 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Triple Differential Driver With Sync-On-Common-Mode |
| AD8134ACP-R2 | 制造商:Analog Devices 功能描述:SP Amp DIFF Line Driver Amp Triple 制造商:Analog Devices 功能描述:SP AMP DIFF LINE DRVR AMP TRIPLE 6V/6V 24LFCSP EP - Tape and Reel |
| AD8134ACP-REEL | 制造商:AD 制造商全稱:Analog Devices 功能描述:Triple Differential Driver With Sync-On-Common-Mode |
| AD8134ACP-REEL7 | 制造商:Analog Devices 功能描述:SP Amp DIFF Line Driver Amp Triple 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| AD8134ACPZ-R2 | 制造商:Analog Devices 功能描述:SP Amp DIFF Line Driver Amp Triple |
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