參數(shù)資料
型號(hào)： OPA2652U2K5
英文描述： Dual, 700MHz, Voltage-Feedback OPERATIONAL AMPLIFIER
中文描述： 雙通道，700MHz的，電壓反饋運(yùn)算放大器
文件頁數(shù)： 13/20頁
文件大?。?/td> 297K
代理商： OPA2652U2K5
www.ti.com
OPERATING SUGGESTIONS
Optimizing Resistor Values
Inverting Amplifier Operation
Bandwidth vs Gain: Noninverting Operation
OPA2652
SBOS125A–JUNE 2000–REVISED MAY 2006
causes the phase margin to approach 90
°
and the
bandwidth to more closely approach the predicted
value of (GBP/NG). At a gain of +5, the 45MHz
bandwidth shown in the Electrical Characteristics is
close to that predicted using this simple formula.
Because the OPA2652 is a unity gain stable voltage
feedback op amp, a wide range of resistor values
may be used for the feedback and gain setting
resistors. The primary limits on these values are set
by dynamic range (noise and distortion) and parasitic
capacitance considerations. For a noninverting unity
gain follower application, the feedback connection
should be made with a 25
resistor, not a direct
short. This configuration isolates the inverting input
capacitance from the output pin and improves the
frequency response flatness. Usually, the feedback
resistor value should be between 200
and 1.5k
.
Below
200
,
the
feedback
additional output loading that can degrade the
harmonic distortion performance of the OPA2652.
Above
1.5k
,
the
typical
(approximately 0.2pF) across the feedback resistor
may cause unintentional bandlimiting in the amplifier
response.
Because
wideband voltage feedback op amp, all of the
familiar op amp application circuits are available to
the designer. Inverting operation is one of the more
common
requirements
performance benefits.
Figure 29
shows a typical
inverting configuration.
the
OPA2652
is
a
general-purpose,
and
offers
several
In the inverting configuration, three key design
consideration must be noted. First, the gain resistor
(R
) becomes part of the signal channel input
impedance. If input impedance matching is desired
(which is beneficial whenever the signal is coupled
through a cable, twisted pair, long PCB trace or other
transmission line conductor), R
G
may be set equal to
the required termination value and R
F
adjusted to
give the desired gain. This approach is the simplest,
and
results
in
optimum
performance. However, at low inverting gains, the
resulting feedback resistor value can present a
significant load to the amplifier output. For an
inverting gain of –1, setting R
G
to 50
for input
matching eliminates the need for R
but requires a
50
W
feedback resistor. This configuration has the
interesting advantage that the noise gain becomes
equal to 2 for a 50
source impedance—the same
as
the
noninverting
circuits
However, the amplifier output now sees the 50
feedback resistor in parallel with the external load. In
general, the feedback resistor should be limited to
the 200
to 1.5k
range. In this case, it is preferable
to increase both the R
and R
values as shown in
Figure 29
, and then achieve the input matching
impedance with a third resistor (R
M
) to ground. The
total
input
impedance
combination of R
G
and R
M
.
The second major consideration, touched on in the
previous
paragraph,
is
impedance becomes part of the noise gain equation
and influences the bandwidth. For the example in
Figure 29
, the R
value combines in parallel with the
external 50
source impedance, yielding an effective
driving impedance of 50
|| 57.6
= 26.8
. This
impedance is added in series with R
for calculating
the noise gain (NG). The resulting NG is 1.94 for
Figure 29
(an ideal source would cause NG = 2.00).
network
presents
parasitic
capacitance
A good rule of thumb is to target the parallel
combination of R
F
and R
G
(see
Figure 28
) to be less
than approximately 300
. The combined impedance
R
||
R
interacts
with
capacitance,
placing
an
feedback network, and thus a zero in the forward
response. Assuming a 2pF total parasitic on the
inverting node, holding R
F
|| R
G
< 300
keeps this
pole above 250MHz. By itself, this constraint implies
that the feedback resistor R
can increase to several
k
at high gains. This increase is acceptable as long
as the pole formed by R
F
capacitance appearing in parallel is kept out of the
frequency range of interest.
bandwidth
and
noise
the
inverting
pole
input
the
additional
in
considered
above.
and any parasitic
Voltage
closed-loop
increased. In theory, this relationship is described by
the Gain Bandwidth Product (GBP) shown in the
specifications.
Ideally,
noninverting signal gain (also called the Noise Gain,
or NG) predicts the closed-loop bandwidth. In
practice, this prediction only holds true when the
phase margin approaches 90
°
, as it does in high
gain
configurations.
At
feedback factor), most amplifiers exhibit a wider
bandwidth and lower phase margin. The OPA2652 is
compensated
to
give
noninverting
gain
of
1
configuration results in a typical gain of +1 bandwidth
of 700MHz, far exceeding that predicted by dividing
the 200MHz GBP by NG = 1. Increasing the gain
feedback
bandwidth
op
amps
as
exhibit
the
decreasing
gain
signal
is
becomes
the
parallel
dividing
GBP
by
the
that
the
signal
source
low
gains
(increased
a
flat
response
Figure
in
a
(see
28
).
This
The
amplifier
cancellation resistor on the noninverting input (R
B
). If
this resistor is set equal to the total DC resistance
looking out of the inverting node, the output DC
third
important
design
consideration
setting
in
inverting
current
is
the
bias
13
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
OPA2652UG4 功能描述:高速運(yùn)算放大器 Dual 700MHz Voltage Feedback 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
OPA2658E 制造商:Rochester Electronics LLC 功能描述:- Bulk
OPA2658E1250 制造商:Rochester Electronics LLC 功能描述:- Bulk
OPA2658P 功能描述:高速運(yùn)算放大器 Dual Wideband 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
OPA2658U 功能描述:高速運(yùn)算放大器 Dual Wideband 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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