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參數(shù)資料
| 型號： | LMV797MM |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運動控制電子 |
| 英文描述： | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| 中文描述： | DUAL OP-AMP, 1350 uV OFFSET-MAX, 14 MHz BAND WIDTH, PDSO8 |
| 封裝： | MSOP-8 |
| 文件頁數(shù)： | 14/19頁 |
| 文件大?。?/td> | 1152K |
| 代理商： | LMV797MM |
Application Information
(Continued)
For simplicity, the op amp is modeled as an ideal integrator
with a unity gain frequency ofA
. Hence, its transfer function
(or gain) in the frequency domain is A
/s. Solving the circuit
equations in the frequency domain, ignoring C
for the mo-
ment, results in an expression for the gain shown in
Equation
(1)
.
(1)
It can be inferred from the denominator of the transfer func-
tion that it has two poles, whose expressions can be ob-
tained by solving for the roots of the denominator and are
shown in
Equation (2)
.
(2)
Equation (2)
shows that as the values of R
and R
are
increased, the magnitude of the poles, and hence the band-
width of the amplifier, is reduced. This theory is verified by
using different values of R
and R
in the circuit shown in
Figure 1
and by comparing their frequency responses. In
Figure 3
the frequency responses for three different values
of R
and R
are shown. When both R
and R
are 1 k
, the
response is flattest and widest; whereas, it narrows and
peaks significantly when both their values are changed to
10 k
or 30 k
. So it is advisable to use lower values of R
1
and R
2
to obtain a wider and flatter response. Lower resis-
tances also help in high sensitivity circuits since they add
less noise.
A way of reducing the gain peaking is by adding a feedback
capacitance C
F
in parallel with R
2
. This introduces another
pole in the system and prevents the formation of pairs of
complex conjugate poles which cause the gain to peak.
Figure 4
shows the effect of C
F
on the frequency response of
the circuit. Adding a capacitance of 2 pF removes the peak,
while a capacitance of 5 pF creates a much lower pole and
reduces the bandwidth excessively.
AUDIO PREAMPLIFIER WITH BAND PASS FILTERING
With low input referred voltage noise, low supply voltage and
current, and a low harmonic distortion, the LMV796 family is
ideal for audio applications. Its wide unity gain bandwidth
allows it to provide large gain for a wide range of frequencies
and it can be used to design a preamplifier to drive a load of
as low as 600
with less than 0.01% distortion. Two ampli-
fier circuits are shown in
Figure 5
and
Figure 6
.
Figure 5
is
an inverting amplifier, with a 10 k
feedback resistor, R
2
,
and a 1k
input resistor, R
, and hence provides a gain of
10.
Figure 6
is a non-inverting amplifier, using the same
values of R
and R
, and provides a gain of 11. In either of
these circuits, the coupling capacitor C
decides the lower
frequency at which the circuit starts providing gain, while the
feedback capacitor C
decides the frequency at which the
gain starts dropping off.
Figure 7
shows the frequency re-
sponse of the inverting amplifier with different values of C
F
.
20183559
FIGURE 3. Gain Peaking Caused by Large R
1
, R
2
20183560
FIGURE 4. Gain Peaking Eliminated by C
F
20183565
FIGURE 5. Inverting Audio Preamplifier
L
www.national.com
14
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV797MM/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMV797MMX | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMV797MMX/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMV8172 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Vertical Deflection Output Amplifier |
| LMV820AILT | 功能描述:運算放大器 - 運放 Low Power OP AMP 400uA 5V 50nA 5.5MHz RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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