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參數(shù)資料
| 型號： | LMV654 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 12 MHz, Low Voltage, Low Power Amplifier |
| 中文描述： | 12兆赫，低電壓，低功耗放大器 |
| 文件頁數(shù)： | 12/16頁 |
| 文件大小： | 408K |
| 代理商： | LMV654 |
The values for R
and C
are decided by ensuring that the
zero attributed to C
lies at the same frequency as the pole
attributed to C
. This ensures that the effect of the second
pole on the transfer function is compensated for by the pres-
ence of the zero, and that the ROC is maintained at 20 dB/
decade. For the circuit shown in
Figure 2
the values of R
and
C
are given by
Equation 1
. Values of R
and C
required for
maintaining stability for different values of C
, as well as the
phase margins obtained, are shown in
Table 1
. R
and R
IN
are taken to be 10 k
, R
L
is 2 k
, while R
OUT
is taken as
340
.
(1)
TABLE 1.
C
F
(pF)
15
20
25
C
L
(pF)
150
200
250
R
S
340
340
340
()
Phase Margin (°)
39.4
34.6
31.1
Although this methodology provides circuit stability for any
load capacitance, it does so at the price of bandwidth. The
closed loop bandwidth of the circuit is now limited by R
F
and
C
F
.
Compensation By External Resistor
In some applications it is essential to drive a capacitive load
without sacrificing bandwidth. In such a case, in the loop com-
pensation is not viable. A simpler scheme for compensation
is shown in
Figure 3
. A resistor, R
, is placed in series be-
tween the load capacitance and the output. This introduces a
zero in the circuit transfer function, which counteracts the ef-
fect of the pole formed by the load capacitance, and ensures
stability. The value of R
ISO
to be used should be decided de-
pending on the size of C
and the level of performance de-
sired. Values ranging from 5
to 50
are usually sufficient to
ensure stability. A larger value of R
will result in a system
with lesser ringing and overshoot, but will also limit the output
swing and the short circuit current of the circuit.
20123860
FIGURE 3. Compensation by Isolation Resistor
Typical Applications
HIGH GAIN LOW POWER AMPLIFIERS
With a low supply current, low power operation, and low har-
monic distortion, the LMV651/LMV652/LMV654 are ideal for
wide-bandwidth, high gain amplification. The wide unity gain
bandwidth allows these parts to provide large gain over a wide
frequency range, while driving loads as low as 2 k
with less
than 0.003% distortion. Two amplifier circuits are shown in
Figure 4
and
Figure 5
.
Figure 4
is an inverting amplifier, with
a 100 k
feedback resistor, R
, and a 1 k
input resistor,
R
, and provides a gain of 100. With the LMV651/LMV652/
LMV654 these circuits can provide gain of 100 with a 3 dB
bandwidth of 120 kHz, for a quiescent current as low as 116
μ
A. Similarly, the circuit in
Figure 5
, a non-inverting amplifier
with a gain of 1001, can provide that gain with a 3 dB band-
width of 12 kHz, for a similar low quiescent power dissipation.
Coupling capacitors C
and C
C2
can be added to isolate the
circuit from DC voltages, while R
and R
provide DC bias-
ing. A feedback capacitor C
F
can also be added to improve
compensation.
20123861
FIGURE 4. High Gain Inverting Amplifier
20123862
FIGURE 5. High Gain Non-Inverting Amplifier
ACTIVE FILTERS
With a wide unity gain bandwidth of 12 MHz, low input referred
noise density and a low power supply current, the LMV651/
LMV652/LMV654 are well suited for low-power filtering appli-
cations. Active filter topologies, like the Sallen-Key low pass
filter shown in
Figure 6
, are very versatile, and can be used
to design a wide variety of filters (Chebyshev, Butterworth or
Bessel). The Sallen-Key topology, in particular, can be used
to attain a wide range of Q, by using positive feedback to re-
ject the undesired frequency range.
www.national.com
12
L
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV654MT | 制造商:Texas Instruments 功能描述:OP Amp Quad GP R-R O/P 5.5V 14-Pin TSSOP Rail 制造商:Texas Instruments 功能描述:OP AMP, QUAD, 12MHZ, TSSOP, POWERWISE |
| LMV654MT/MESN | 制造商:Texas Instruments 功能描述: |
| LMV654MT/NOPB | 功能描述:運算放大器 - 運放 Quad 12Mhz Low Vltg 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 |
| LMV654MTX | 制造商:Texas Instruments 功能描述:OP Amp Quad GP R-R O/P 5.5V 14-Pin TSSOP T/R |
| LMV654MTX/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 |
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