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參數(shù)資料
| 型號： | CLC420 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | High-Speed, Voltage Feedback Op Amp |
| 中文描述： | 高速，電壓反饋運算放大器 |
| 文件頁數(shù)： | 8/10頁 |
| 文件大?。?/td> | 286K |
| 代理商： | CLC420 |
Application Division
(Continued)
Transimpedance amplifier circuits
Low inverting, input current noise (2pA/
CLC420 ideal for high-sensitivity transimpedance amplifier
circuits for applications such as pin-diode optical receivers,
and detectors in receiver IFs. However, feedback resistors
4k
or greater are required if feedback resistor noise current
is going to be less than the input current noise contribution of
the op-amp.
With feedback resistors this large, shunt capacitance on the
inverting input of the op-amp (from the pin-diode, etc.) will
unacceptably degrade phase margin causing frequency re-
sponse peaking or oscillations a small valued capacitor
shunting the feedback resistor solves this problem (Note:
This approach does not work for a current-feedback op-amp
configured for transimpedance applications). To determine
the value of this capacitor, refer to the “Transimpedance BW
vs. R
f
and C
i
” plot.
For example, let’s assume an optical transimpedance re-
ceiver is being developed. Total capacitance from the invert-
ing input to ground, including the photodiode and strays is
5pF. A 5k
feedback resistor value has been determined to
provide best dynamic range based on the response of the
photodiode and the range of incident optical powers, etc.
) makes the
From the “Transimpedance BW vs. R
and C
” plot, using
C
=5pF it is determined from the two curves labeled C
=5pF,
that C
=1.5pF provides optimal compensation (no more than
0.5dB frequency response peaking) and a 3dB bandwidth
of approximately 27MHz.
Printed circuit layout
As with any high frequency device, a good PCB layout will
enhance performance. Ground plane construction and good
power supply bypassing close to the package are critical to
achieving full performance. The amplifier is sensitive to stray
capacitance to ground at the output and inverting input:
Node connections should be small with minimal coupling to
the ground plane.
Parasitic or load capacitance directly on the output (pin 6)
will introduce additional phase shift in the loop degrading the
loop phase margin and leading to frequency response peak-
ing. A small series resistor before this capacitance, if
present, effectively decouples this effect. The graphs on the
preceding page, “ Settling Time vs. C
”, illustrates the re-
quired resistor value and resulting performance vs. capaci-
tance.
Evaluation PC boards (part no. 730013 for through-hole and
CLC730027 for SOIC) are available for the CLC420.
C
www.national.com
8
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| CLC425AJP | Circular Connector; No. of Contacts:16; Series:MS27473; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:20; Circular Contact Gender:Socket; Circular Shell Style:Straight Plug; Insert Arrangement:20-16 RoHS Compliant: No |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| CLC420AE-QML | 制造商:Rochester Electronics LLC 功能描述:HI SPEED VOLTAGE FEEDBK OP AMP - Bulk 制造商:Texas Instruments 功能描述: |
| CLC420AIB | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| CLC420AID | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| CLC420AJE | 制造商:Texas Instruments 功能描述:Operational Amplifier, Single AMP, Bipolar, 8 Pin, Plastic, SOP |
| CLC420AJE-TR13 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:High-Speed, Voltage Feedback Op Amp |
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