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參數(shù)資料
| 型號： | OPA3684IDR |
| 英文描述： | Operational Amplifier |
| 中文描述： | 運算放大器 |
| 文件頁數(shù)： | 12/25頁 |
| 文件大?。?/td> | 448K |
| 代理商： | OPA3684IDR |
OPA3684
SBOS241A
12
www.ti.com
APPLICATIONS INFORMATION
LOW-POWER, CURRENT-FEEDBACK OPERATION
The triple-channel OPA3684 gives a new level of perfor-
mance in low-power, current-feedback op amps. Using a
new input stage buffer architecture, the OPA3684 CFB
PLUS
amplifier holds nearly constant AC performance over a wide
gain range. This closed-loop internal buffer gives a very low
and linearized impedance at the inverting node, isolating the
amplifier
’
s AC performance from gain element variations.
This allows both the bandwidth and distortion to remain
nearly constant over gain, moving closer to the ideal current-
feedback performance of gain bandwidth independence.
This low-power amplifier also delivers exceptional output
power
—
it
’
s
±
4V swing on
±
5V supplies with > 100mA output
drive gives excellent performance into standard video loads
or doubly-terminated 50
cables. Single +5V supply opera-
tion is also supported with similar bandwidths but with re-
duced output power capability. For lower quiescent power in
a CFB
PLUS
amplifier, consider the OPA683 family; while for
higher output power, consider the OPA691 family.
Figure 1 shows the DC-coupled, gain of +2, dual power-
supply circuit used as the basis of the
±
5V Electrical and
Typical Characteristics for each channel. For test purposes,
the input impedance is set to 50
with a resistor to ground
and the output impedance is set to 50
with a series output
resistor. Voltage swings reported in the Electrical Character-
istics are taken directly at the input and output pins while load
powers (dBm) are defined at a matched 50
load. For
the circuit of Figure 1, the total effective load will be
100
|| 1600
= 94
. Gain changes are most easily accom-
plished by simply resetting the R
G
value, holding R
F
constant
at its recommended value of 800
.
mode signal across the input stage, the slew rate for inverting
operation is typically higher and the distortion performance is
slightly improved. An additional input resistor, R
M
, is included
in Figure 2 to set the input impedance equal to 50
. The
parallel combination of R
M
and R
G
set the input impedance.
As the desired gain increases for the inverting configuration,
R
G
is adjusted to achieved the desired gain, while R
M
is also
adjusted to hold a 50
input match. A point will be reached
where R
G
will equal 50
, R
M
is removed, and the input match
is set by R
G
only. With R
G
fixed to achieve an input match to
50
, increasing R
F
will increase the gain. This will, however,
quickly reduce the achievable bandwidth as the feedback
resistor increases from its recommended value of 800
. If
the source does not require an input match to 50
, either
adjust R
M
to get the desired load, or remove it and let the R
G
resistor alone provide the input load.
R
F
800
1/3
OPA3684
+5V
–
5V
50
R
M
50
R
G
800
50
Source
50
Load
V
I
0.1
μ
F
6.8
μ
F
0.1
μ
F
6.8
μ
F
+
+
DIS
FIGURE 1. DC-Coupled, G = +2V/V, Bipolar Supply Speci-
fications and Test Circuit.
FIGURE 2. DC-Coupled, G =
–
1V/V, Bipolar Supply Specifi-
cations and Test Circuit.
Figure 2 shows the DC-coupled, gain of
–
1V/V, dual power-
supply circuit used as the basis of the Inverting Typical
Characteristics for each channel. Inverting operation offers
several performance benefits. Since there is no common-
These circuits show
±
5V operation. The same circuits can be
applied with bipolar supplies from
±
2.5V to
±
6V. Internal
supply independent biasing gives nearly the same perfor-
mance for the OPA3684 over this wide range of supplies.
Generally, the optimum feedback resistor value (for nomi-
nally flat frequency response at G = +2) will increase in value
as the total supply voltage across the OPA3684 is reduced.
See Figure 3 for the AC-coupled, single +5V supply, gain of
+2V/V circuit configuration used as a basis for the +5V only
Electrical and Typical Characteristics for each channel. The
key requirement of broadband single-supply operation is to
maintain input and output signal swings within the usable
voltage ranges at both the input and the output. The circuit
of Figure 3 establishes an input midpoint bias using a simple
resistive divider from the +5V supply (two 10k
resistors) to
the noninverting input. The input signal is then AC-coupled
into this midpoint voltage bias. The input voltage can swing
to within 1.25V of either supply pin, giving a 2.5Vp-p input
signal range centered between the supply pins. The input
impedance of Figure 3 is set to give a 50
input match. If the
source does not require a 50
match, remove this and drive
R
F
800
1/3
OPA3684
+5V
–
5V
50
R
53.6
R
G
800
50
Load
50
Source
0.1
μ
F
6.8
μ
F
0.1
μ
F
6.8
μ
F
+
+
V
I
DIS
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA3684IDRG4 | 功能描述:高速運算放大器 Low-Power Triple Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補償電壓: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 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| OPA369 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.8V, 700nA, Zer?-Crossover RAIL-TO-RAIL I/O OPERATIONAL AMPLIFIER |
| OPA369_1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.8V, 700nA, Zer?-Crossover RAIL-TO-RAIL I/O OPERATIONAL AMPLIFIER |
| OPA3690 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Dual, Wideband, High Output Current, Operational Amplifier with Current Limit |
| OPA3690ID | 功能描述:高速運算放大器 Triple Wideband 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 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
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