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參數(shù)資料
| 型號(hào)： | OPA2607U |
| 英文描述： | Dual, High Output, Current-Feedback OPERATIONAL AMPLIFIER |
| 中文描述： | 雙路，高輸出，電流反饋運(yùn)算放大器 |
| 文件頁數(shù)： | 8/13頁 |
| 文件大?。?/td> | 174K |
| 代理商： | OPA2607U |
8
OPA2607
If 20
log (R
F
+ NG
R
I
) were drawn on top of the open-
loop transimpedance plot, the difference between the two
would be the loop gain at a given frequency. Eventually,
Z(s) rolls off to equal the denominator of Equation 2 at
which point the loop gain has reduced to 1 (and the curves
have intersected). This point of equality is where the
amplifier’s closed-loop frequency response given by Equa-
tion 1 will start to roll off, and is exactly analogous to the
frequency at which the noise gain equals the open-loop
voltage gain for a voltage-feedback op amp. The difference
here is that the total impedance in the denominator of
Equation 2 may be controlled somewhat separately from the
desired signal gain (or NG).
The OPA2607 is internally compensated to give a maxi-
mally flat frequency response for R
F
= 1.21k
at NG = 8 on
±
12V supplies. Evaluating the denominator of Equation 2
target of 1.44k
. As the signal gain changes, the contribu-
tion of the NG
x
R
I
term in the feedback transimpedance will
change, but the total can be held constant by adjusting R
F
.
Equation 3 gives an approximate equation for optimum R
F
over signal gain:
As the desired signal gain increases, this equation will
eventually predict a negative R
F
. A somewhat subjective
limit to this adjustment can also be set by holding R
G
to a
minimum value of 20
. Lower values will load both the
buffer stage at the input and the output stage if R
F
gets too
low—actually decreasing the bandwidth. Figure 3 shows the
recommended R
F
versus NG. The values for R
F
versus Gain
shown here are approximately equal to the values used to
generate the typical performance curves. They differ in that
the optimized values used in the typical performance curves
are also correcting for board parasitics not considered in the
simplified analysis leading to Equation 3. The values shown
in Figure 3 give a good starting point for design where
bandwidth optimization is desired.
The total impedance going into the inverting input may be
used to adjust the closed-loop signal bandwidth. Inserting a
series resistor between the inverting input and the summing
junction will increase the feedback impedance (denominator
of Equation 2), decreasing the bandwidth. The internal
buffer output impedance for the OPA2607 is slightly influ-
enced by the source impedance looking out of the non-
inverting input terminal. High-source resistors will have the
effect of increasing R
I
, decreasing the bandwidth. For those
single-supply applications which develop a midpoint bias at
the non-inverting input through high-valued resistors, the
decoupling capacitor is essential for power-supply ripple
rejection, non-inverting input-noise current shunting, and to
minimize the high frequency value for R
I
in Figure 2.
INVERTING AMPLIFIER OPERATION
Since the OPA2607 is a wideband, current-feedback op
amp, most of the familiar op amp application circuits are
available to the designer. Those dual op amp applications
that require considerable flexibility in the feedback element
(e.g. integrators, transimpedance, some filters) should con-
sider the unity gain stable voltage-feedback OPA2680, since
the feedback resistor is the compensation element for a
current-feedback op amp. Wideband inverting operations
(and especially summing) are particularly suited to the
OPA2607. Figure 4 shows a typical inverting configuration
where the I/O impedances are 50
.
(3)
1600
1400
1200
1000
800
600
400
200
0
Noise Gain, NG (V/V)
0
20
10
15
5
FEEDBACK RESISTOR vs NOISE GAIN
F
F
)
FIGURE 3. Recommended Feedback Resistor vs Noise
Gain.
1/2
OPA2607
R
F
1.21k
R
G
150
+12V
–12V
49.9
50
Load
V
O
Power supply
de-coupling
not shown
V
I
50
Source
R
M
75.0
FIGURE 4. Inverting Gain of –8 with Impedance Matching.
In the inverting configuration, two key design consider-
ations must be noted. The first is that the gain resistor (R
G
)
becomes part of the signal-channel input impedance. If input
impedance matching is desired (which is beneficial when-
ever the signal is coupled through a cable, twisted pair, long
PC board trace, or other transmission line conductor), it is
normally necessary to add an additional matching resistor
(R
M
) to ground. R
G
by itself is normally not set to the
required input impedance since its value, along with the
desired gain, will determine an R
F
which may be non-
optimal from a frequency response standpoint. The total
input impedance for the source becomes the parallel combi-
nation of R
G
and R
M
.
R
NG R
F
I
=
1441
–
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參數(shù)描述 |
|---|---|
| OPA2607U/2K5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OPA260FJ | 制造商:Analog Devices 功能描述: |
| OPA2613ID | 功能描述:高速運(yùn)算放大器 Dual Wideband Hi-Output Current 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 |
| OPA2613ID | 制造商:Texas Instruments 功能描述:IC |
| OPA2613IDG4 | 功能描述:高速運(yùn)算放大器 Dual Wideband Hi-Output Current 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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