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參數(shù)資料
| 型號： | OPA640 |
| 英文描述： | Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| 中文描述： | 寬帶電壓反饋運算放大器 |
| 文件頁數(shù)： | 7/13頁 |
| 文件大?。?/td> | 190K |
| 代理商： | OPA640 |
OPA640
7
TYPICAL PERFORMANCE CURVES
(CONT)
T
A
= +25
°
C, V
S
=
±
5V, R
L
= 100
, C
L
= 2pF, R
FB
= 402
and all four power supply pins are used, unless otherwise noted. R
FB
= 25
for a gain of +1.
APPLICATIONS INFORMATION
DISCUSSION OF PERFORMANCE
The OPA640 provides a level of speed and precision not
previously attainable in monolithic form. Unlike current
feedback amplifiers, the OPA640’s design uses a “Classi-
cal” operational amplifier architecture and can therefore be
used in all traditional operational amplifier applications.
While it is true that current feedback amplifiers can provide
wider bandwidth at higher gains, they offer some disadvan-
tages. The asymmetrical input characteristics of current
feedback amplifiers (i.e. one input is a low impedance)
prevents them from being used in a variety of applications.
In addition, unbalanced inputs make input bias current errors
difficult to correct. Cancelling offset errors (due to input bias
currents) through matching of inverting and non-inverting
input resistors is impossible because the input bias currents
are uncorrelated. Current noise is also asymmetrical and is
usually significantly higher on the inverting input. Perhaps
most important, settling time to 0.01% is often extremely
poor due to internal design tradeoffs. Many current feedback
designs exhibit settling times to 0.01% in excess of 10
microseconds
even though 0.1% settling times are reason-
able. Such amplifiers are completely inadequate for fast
settling 12-bit applications.
The OPA640’s “Classical” operational amplifier architec-
ture employs true differential and fully symmetrical inputs
to eliminate these troublesome problems. All traditional
circuit configurations and op amp theory apply to the
OPA640.
WIRING PRECAUTIONS
Maximizing the OPA640’s capability requires some wiring
precautions and high-frequency layout techniques. Oscilla-
tion, ringing, poor bandwidth and settling, gain peaking, and
instability are typical problems plaguing all high-speed
amplifiers when they are improperly used. In general, all
printed circuit board conductors should be wide to provide
low resistance, low impedance signal paths. They should
also be as short as possible. The entire physical circuit
should be as small as practical. Stray capacitances should be
minimized, especially at high impedance nodes, such as the
amplifier’s input terminals. Stray signal coupling from the
output or power supplies to the inputs should be minimized.
All circuit element leads should be no longer than 1/4 inch
(6mm) to minimize lead inductance, and low values of
resistance should be used. This will minimize time constants
formed with the circuit capacitances and will eliminate
stray, parasitic circuits.
Grounding is the most important application consideration
for the OPA640, as it is with all high-frequency circuits.
Oscillations at high frequencies can easily occur if good
grounding techniques are not used. A heavy ground plane
(2oz copper recommended) should connect all unused areas
on the component side. Good ground planes can reduce stray
signal pickup, provide a low resistance, low inductance
common return path for signal and power, and can conduct
heat from active circuit package pins into ambient air by
convection.
Supply bypassing is extremely critical and must
always
be
used, especially when driving high current loads. Both
power supply leads should be bypassed to ground as close as
possible to the amplifier pins. Tantalum capacitors (2.2
μ
F)
with very short leads are recommended. A parallel 0.01
μ
F
ceramic must also be added. Surface mount bypass capaci-
tors will produce excellent results due to their low lead
inductance. Additionally, suppression filters can be used to
isolate noisy supply lines. Properly bypassed and modula-
tion-free power supply lines allow full amplifier output and
optimum settling time performance.
–65
–75
–85
–95
0
Output Swing (Vp-p)
H
10MHz HARMONIC DISTORTION vs OUTPUT SWING
(G = +1, R
L
= 100
)
1.0
2.0
3.0
4.0
2f
O
3f
O
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OPA640P | Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| OPA640U | Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| OPA640UB | Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| OPA642 | Wideband, Low Distortion, Low Gain OPERATIONAL AMPLIFIER |
| OPA642N | Wideband, Low Distortion, Low Gain OPERATIONAL AMPLIFIER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA640P | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Texas Instruments 功能描述: |
| OPA640U | 制造商:BB 制造商全稱:BB 功能描述:Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| OPA640UB | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OPA641 | 制造商:BB 制造商全稱:BB 功能描述:Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
| OPA641H | 制造商:BB 制造商全稱:BB 功能描述:Wideband Voltage Feedback OPERATIONAL AMPLIFIER |
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