參數(shù)資料
型號: LMV771MGX
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 運(yùn)算放大器
英文描述: Single/Dual/Quad, Low Offset, Low Noise, RRO Operational Amplifiers
中文描述: OP-AMP, 1000 uV OFFSET-MAX, 3.5 MHz BAND WIDTH, PDSO5
封裝: SC-70, 5 PIN
文件頁數(shù): 14/21頁
文件大小: 844K
代理商: LMV771MGX
Application Note
(Continued)
ACTIVE FILTER
Active Filters are circuits with amplifiers, resistors, and ca-
pacitors. The use of amplifiers instead of inductors, which
are used in passive filters, enhances the circuit performance
while reducing the size and complexity of the filter.
The simplest active filters are designed using an inverting op
amp configuration where at least one reactive element has
been added to the configuration. This means that the op amp
will provide "frequency-dependent" amplification, since reac-
tive elements are frequency dependent devices.
LOW PASS FILTER
The following shows a very simple low pass filter.
The transfer function can be expressed as follows:
By KCL:
(7)
Simplifying this further results in:
(8)
or
(9)
Now, substituting
ω
=2
π
f, so that the calculations are in f(Hz)
and not
ω
(rad/s), and setting the DC gain
and
(10)
Set:
(11)
Low pass filters are known as lossy integrators because they
only behave as an integrator at higher frequencies. Just by
looking at the transfer function one can predict the general
form of the bode plot. When the f/f
O
ratio is small, the
capacitor is in effect an open circuit and the amplifier be-
haves at a set DC gain. Starting at f
O
, 3dB corner, the
capacitor will have the dominant impedance and hence the
circuit will behave as an integrator and the signal will be
attenuated and eventually cut. The bode plot for this filter is
shown in the following picture:
20039673
FIGURE 2. CMRR vs. Frequency
20039647
FIGURE 3.
20039653
FIGURE 4.
L
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14
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LMV771MGX/NOPB 功能描述:運(yùn)算放大器 - 運(yùn)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(bǔ)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
LMV772 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Single/Dual/Quad, Low Offset, Low Noise, RRO Operational Amplifiers
LMV772MA 功能描述:運(yùn)算放大器 - 運(yùn)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(bǔ)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
LMV772MA/NOPB 功能描述:運(yùn)算放大器 - 運(yùn)放 Low Noise,Dual Prec Op Amp 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(bǔ)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
LMV772MAX 功能描述:運(yùn)算放大器 - 運(yùn)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(bǔ)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