參數(shù)資料
型號(hào)： OPA2381AIDRBR
元件分類(lèi)： 跨阻放大器
英文描述： Precision, Low Power, 18MHz Transimpedance Amplifier
中文描述： 精密，低功耗，18MHz的阻放大器
文件頁(yè)數(shù)： 10/19頁(yè)
文件大?。?/td> 489K
代理商： OPA2381AIDRBR
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SBOS313B AUGUST 2004 REVISED NOVEMBER 2004
www.ti.com
10
BIASING PHOTODIODES IN SINGLE-SUPPLY
CIRCUITS
The +IN input can be biased with a positive DC voltage
to offset the output voltage and allow the amplifier
output to indicate a true
zero
photodiode measurement
when the photodiode is not exposed to any light. It will
also prevent the added delay that results from coming
out of the negative rail. This bias voltage appears
across the photodiode, providing a reverse bias for
faster operation. An RC filter placed at this bias point will
reduce noise. (Refer to Figure 4.) This bias voltage can
also serve as an offset bias point for an ADC with range
that does not include ground.
OPA381
V
OUT
= I
D
R
F
+ V
BIAS
100k
V+
R
F
10M
I
D
C
F(1)
< 1pF
0.1
μ
F
λ
NOTE: (1) C
is optional to prevent gain peaking.
It includes the stray capacitance of R
F
.
+V
BIAS
[0V to (V+)
1.8V]
Figure 4. Photodiode with Filtered Reverse Bias
Voltage
TRANSIMPEDANCE AMPLIFIER
Wide bandwidth, low input bias current and low input
voltage and current noise make the OPA381 an ideal
wideband photodiode transimpedance amplifier. Low
voltage noise is important because photodiode
capacitance causes the effective noise gain of the
circuit to increase at high frequency.
The key elements to a transimpedance design are
shown in Figure 5:
the total input capacitance (C
TOT
), consisting of the
photodiode capacitance (C
DIODE
) plus the parasitic
common-mode
and
capacitance (2.5pF + 1pF for the OPA381);
differential-mode
input
the desired transimpedance gain (R
F
);
the Gain Bandwidth Product (GBW) for the
OPA381 (18MHz).
With these three variables set, the feedback capacitor
value (C
F
) can be set to control the frequency response.
C
STRAY
is the stray capacitance of R
F
, which is 0.2pF for
a typical surface-mount resistor.
To achieve a maximally flat 2nd-order Butterworth
frequency response, the feedback pole should be set
to:
1
2 R
F
C
F
C
STRAY
GBW
4 R
F
C
TOT
Bandwidth is calculated by:
f
3dB
GBW
2 R
F
C
TOT
Hz
These
transimpedance
transimpedance bandwidth, the high-speed CMOS
OPA380 (90MHz GBW), the OPA300 (150MHz GBW),
or the OPA656 (230MHz GBW) may be used.
For additional information, refer to Application Bulletin
AB050 (SBOA055),
Compensate Transimpedance
Amplifiers Intuitively
, available for download at
www.ti.com
.
equations
will
result
in
even
maximum
higher
bandwidth.
For
C
TOT(3)
OPA381
V
OUT
5V
10M
+5V
R
F
C
F(1)
C
STRAY(2)
λ
NOTE: (1) C
F
is optional to prevent gain peaking.
(2) C
is the stray capacitance of R
(typically, 0.2pF for a surfacemount resistor).
(3) C
is the photodiode capacitance plus OPA381
input capacitance.
R
(optional
pulldown resistor)
Figure 5. Transimpedance Amplifier
(1)
(2)
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OPA2381AIDRBRG4 功能描述:運(yùn)算放大器 - 運(yùn)放 Precision Lo-Power Transimpedance RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
OPA2381AIDRBT 功能描述:運(yùn)算放大器 - 運(yùn)放 Precision Lo-Power Transimpedance RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
OPA2381AIDRBTG4 功能描述:運(yùn)算放大器 - 運(yùn)放 Precision Lo-Power Transimpedance RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
OPA241PA 功能描述:運(yùn)算放大器 - 運(yùn)放 Single-Supply MicroPower Oper Amp RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
OPA241PA 制造商:BURR-BROWN 功能描述:IC OP-AMP MICROPOWER
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