參數(shù)資料
型號(hào)： OPA4658UB
英文描述： Quad Wideband, Low Power Current Feedback OPERATIONAL AMPLIFIER
中文描述： 四組寬頻，低功耗電流反饋運(yùn)算放大器
文件頁(yè)數(shù)： 8/14頁(yè)
文件大?。?/td> 247K
代理商： OPA4658UB
8
OPA4658
For non-inverting operation, the input signal is applied to the
non-inverting (high impedance buffer) input. The output
(buffer) error current (I
E
) is generated at the low impedance
inverting input. The signal generated at the output is fed back
to the inverting input such that the overall gain is (1 + R
FB
/R
FF
).
Where a voltage-feedback amplifier has two symmetrical high
impedance inputs, a current feedback amplifier has a low
inverting (buffer output) impedance and a high non-inverting
(buffer input) impedance.
The closed-loop gain for the OPA4658 can be calculated
using the following equations:
(1)
(2)
At higher gains the small value inverting input impedance
causes an apparent loss in bandwidth. This can be seen from
the equation:
ACTUAL
BW
≈
1
+
(3)
This loss in bandwidth at high gains can be corrected
without affecting stability by lowering the value of the
feedback resistor from the specified value of 402
.
OFFSET VOLTAGE AND NOISE
The output offset is the algebraic sum of the input offset
voltage and bias current errors. The output offset for non-
inverting operation is calculated by the following equation:
(4)
If all terms are divided by the gain (1 + R
FB
/R
FF
) it can be
observed that input referred offsets improve as gain increases.
The effective noise at the output can be determined by taking
APPLICATIONS INFORMATION
THEORY OF OPERATION
Conventional op amps depend on feedback to drive their
inputs to the same potential, however the current feedback
op amp’s inverting and non-inverting inputs are connected
by a unity gain buffer, thus enabling the inverting input to
automatically assume the same potential as the non-invert-
ing input. This results in very low impedance at the inverting
input to sense the feedback as an error current signal.
DISCUSSION OF PERFORMANCE
The OPA4658 is a low-power, unity gain stable, current
feedback operational amplifier which operates on
±
5V power
supply. The current feedback architecture offers the follow-
ing important advantages over voltage feedback architec-
tures: (1) the high slew rate allows the large signal perfor-
mance to approach the small signal performance, and (2)
there is very little bandwidth degradation at higher gain
settings.
The current feedback architecture of the OPA4658 provides
the traditional strength of excellent large signal response
plus wide bandwidth, making it a good choice for use in high
resolution video, medical imaging and DAC I/V Conver-
sion. The low power requirements make it an excellent
choice for numerous portable applications.
DC GAIN TRANSFER CHARACTERISTICS
The circuit in Figure 1 shows the equivalent circuit for
calculating the DC gain. When operating the device in the
inverting mode, the input signal error current (I
E
) is ampli-
fied by the open loop transimpedance gain (T
O
). The output
signal generated is equal to T
O
x
I
E
. Negative feedback is
applied through R
FB
such that the device operates at a gain
equal to –R
FB
/R
FF
.
FIGURE 1. Equivalent Circuit.
V
O
T
O
C
C
L
S
R
S
(50
)
C
1
V
I
V
N
R
FF
R
FB
I
E
+
–
InvertingGain
=
–
R
FB
R
FF
1
+
1
LoopGain
Non
InvertingGain
=
1
+
R
FB
R
FF
1
+
1
LoopGain
whereLoopGain
=
T
O
R
FB
+
R
S
1
+
R
FB
R
FF
A
V
=+
2
(
)
BW
×
1
+
R
FB
x 1.25
)
R
S
R
FB
R
FF
V
IO
1
+
R
FB
R
FF
±
Ib
I
×
R
FB
OutputOffsetVoltage
= ±
Ib
N
×
R
N
1
+
R
FB
R
FF
±
FIGURE 2. Output Offset Voltage Equivalent Circuit.
R
FB
R
FF
Ib
I
R
N
Ib
N
V
IO
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
OPA4684 制造商:BB 制造商全稱:BB 功能描述:Wideband, Low-Power, Current Feedback Operational Amplifier
OPA4684ID 功能描述:高速運(yùn)算放大器 Quad Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
OPA4684IDBW 制造商:TI 制造商全稱:Texas Instruments 功能描述:QUAD LOW-POWER CURRENT-FEEDBACK OPERATIONAL AMPLIFIER
OPA4684IDG4 功能描述:高速運(yùn)算放大器 Quad Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
OPA4684IDR 功能描述:高速運(yùn)算放大器 Quad Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
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