參數(shù)資料
型號(hào): LMV324MX
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類(lèi): 運(yùn)動(dòng)控制電子
英文描述: General Purpose, Low Voltage, Rail-to-Rail Output Operational Amplifiers
中文描述: QUAD OP-AMP, 9000 uV OFFSET-MAX, 1 MHz BAND WIDTH, PDSO14
封裝: SOIC-14
文件頁(yè)數(shù): 16/27頁(yè)
文件大?。?/td> 1151K
代理商: LMV324MX
Application Notes
(Continued)
Note that the single-op-amp active filters are used in to the
applications that require low quality factor, Q(
10), low
frequency (
5 kHz), and low gain (
10), or a small value for
the product of gain times Q (
100). The op amp should have
an open loop voltage gain at the highest frequency of inter-
est at least 50 times larger than the gain of the filter at this
frequency. In addition, the selected op amp should have a
slew rate that meets the following requirement:
Slew Rate
0.5 x (
ω
H
V
OPP
) x 10
6
V/μsec
where
ω
H
is the highest frequency of interest, and V
opp
is the
output peak-to-peak voltage.
4.4.2 Sallen-Key 2nd-Order Active Low-Pass Filter
The Sallen-Key 2nd-order active low-pass filter is illustrated
in
Figure 13
. The dc gain of the filter is expressed as
(1)
Its transfer function is
(2)
The following paragraphs explain how to select values for
R
, R
2
, R
, R
, C
1
, and C
2
for given filter requirements, such
as A
LP
, Q, and f
c
.
The standard form for a 2nd-order low pass filter is
(3)
where
Q: Pole Quality Factor
ω
C
: Corner Frequency
Comparison between the
Equation (2)
and
Equation (3)
yields
(4)
(5)
To reduce the required calculations in filter design, it is
convenient to introduce normalization into the components
and design parameters. To normalize, let
ω
=
ω
= 1rad/s,
and C
= C
= C
= 1F, and substitute these values into
Equation (4)
and
Equation (5)
. From
Equation (4)
, we obtain
(6)
From
Equation (5)
, we obtain
(7)
10006014
10006037
FIGURE 11. Simple Low-Pass Active Filter
10006015
FIGURE 12. Frequency Response of Simple Low-Pass
Active Filter in Figure 11
10006016
FIGURE 13. Sallen-Key 2nd-Order Active Low-Pass
Filter
L
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LMV324PW 制造商:TI 制造商全稱:Texas Instruments 功能描述:LOW-VOLTAGE RAIL-TO-RAIL OUTPUT OPERATIONAL AMPLIFIERS
LMV324Q1 制造商:TI 制造商全稱:Texas Instruments 功能描述:LOW-VOLTAGE RAIL-TO-RAIL OUTPUT OPERATIONAL AMPLIFIERS
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