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參數(shù)資料
| 型號(hào)： | OPA675 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | Wideband Switched-Input Operational Amplifier(寬帶轉(zhuǎn)換輸入運(yùn)算放大器) |
| 中文描述： | 寬帶開關(guān)輸入運(yùn)算放大器（寬帶轉(zhuǎn)換輸入運(yùn)算放大器） |
| 文件頁數(shù)： | 9/13頁 |
| 文件大?。?/td> | 198K |
| 代理商： | OPA675 |
OPA675/676
9
500
100
100
5-30pf
75
2
1
5
8
+
–
–
+
500
50
To Scope
1MHz
Square
Wave
+0.5V
–0.5V
100
1k
6.5pf
10MHz
50mVp-p
2
1
5
8
OPA676
+
–
–
+
16
15
11
100
1k
3MHz
TTL
100
R
L
12
Tektronix
SG503
To Scope
FIGURE 5. OPA676 Input Selection Transition Time Test
Circuit.
FIGURE 4. OPA675/676 Settling Time Test Circuit.
6.
Wirewound resistors (even “non-inductive” types) are
absolutely unacceptable in high frequency circuits.
Avoid overloading the output. Remember that output
current must be provided by the amplifier to drive its
own feedback network as well as to drive its “l(fā)oad.”
Lowest distortion is achieved with high impedance
loads.
PC board traces for signal and power lines should be
wide to reduce impedance or inductance.
Don’t forget that these amplifiers use
±
5V supplies.
Although they will operate perfectly well with +5V
and –5.2V, the use of
±
15V supplies will result in
destruction.
10. Standard commercial test equipment has not been de-
signed to test devices in the OPA675/676 speed range.
Benchtop op amp testers and ATE systems will require
a special test head to successfully test these amplifiers.
11. High-speed amplifiers can drive only a limited amount
of capacitance. If the load exceeds 10 to 20pF consider
using a fast buffer or a small resistor to isolate the
capacitance from the amplifier’s output. Capacitive
loads will cause loop instability if not compensated for.
12. Terminate transmission line loads. Unterminated lines,
such as coaxial cable, can appear to the amplifier to be
a capacitive or inductive load. By terminating a trans-
mission line with its characteristic impedance, the
amplifier’s load then appears as a purely resistive
impedance.
13. For clean, fast input selection the logic input pins should
be terminated with appropriate resistors. Resistors should
be connected from input selection pins to ground plane
with short leads. Failure to terminate long lines will
result in ringing and poor high frequency switching.
14. Plug-in prototype boards and wire-wrap boards will not
be satisfactory. A clean layout using RF techniques is
required; there is no shortcut.
7.
8.
9.
APPLICATION TIPS
Wideband amplifier circuits require good layout techniques
to be successful. The use of short, direct signal paths and
heavy (2 oz. copper recommended) ground planes are abso-
lutely necessary to achieve the performance level inherent in
the OPA675/676. Oscillation, ringing, poor bandwidth and
settling, gain peaking, and instability are typical problems
that plague all high-speed amplifiers when they are used in
poor layouts. The OPA675 and OPA676 are no different in
this respect—any amplifier with a gain bandwidth product of
a few GHz requires some care be taken in its application.
Points to remember:
1.
Use a heavy copper ground plane on the component side
of your PC board. This provides a low inductance
ground and it also conducts heat from active circuit
package pins into ambient air by convection.
2.
Bypass power supply pins directly at the active device.
The use of tantalum capacitors (1 to 10
μ
F/10V) with
very short leads is highly recommended. Supply pins
should not be left unbypassed.
3.
Signal paths should be short and direct. Feedback
resistors, compensation capacitors, termination resis-
tors, etc., should have lead lengths no longer than 1/4
inch (6cm).
4.
Surface-mount components (chip resistors, capacitors,
etc.) have low inductance and are therefore recom-
mended. Parasitic inductance and capacitance should be
avoided if best performance is to be achieved.
5.
Resistors used in feedback networks should have values
of a few hundred ohms for best performance. Shunt
capacitance problems limit the acceptable range to about
1k
or on the high resistance end and to a value that is
within the amplifier’s output drive limits on the low end.
Metal film and carbon compensation resistors will be
satisfactory.
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| OPA676JG | Wideband Switched-Input OPERATIONAL AMPLIFIER |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA675/OPA676 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:OPA675. OPA676 - DISCONTINUED PRODUCT. No longer recommended for new design. |
| OPA675JG | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Wideband Switched-Input OPERATIONAL AMPLIFIER |
| OPA675KG | 制造商: 功能描述: 制造商:undefined 功能描述: |
| OPA675SG | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Wideband Switched-Input OPERATIONAL AMPLIFIER |
| OPA676 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Wideband Switched-Input OPERATIONAL AMPLIFIER |
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