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參數(shù)資料
| 型號： | OPA847 |
| 英文描述： | Wideband, Ultra-Low Noise, Voltage-Feedback |
| 中文描述： | 寬帶，超低噪聲，電壓反饋 |
| 文件頁數(shù)： | 13/23頁 |
| 文件大小： | 529K |
| 代理商： | OPA847 |
OPA847
SBOS251C
13
www.ti.com
Finally, since C
S
and C
F
set the high-frequency noise gain,
determine C
S
using Equation 6 (solving for C
S
by using NG
2
= 24):
F
2
S
C
)
NG
(
C
=
(6)
which gives C
S
= 40.6pF.
Both of these calculated values have been reduced slightly
in Figure 5 to account for parasitics. The resulting closed-
loop bandwidth is approximately equal to Equation 7.
GBP
Z
f
O
dB
3
–
(7)
For the values shown in Figure 5, f
–3dB
is approximately
131MHz. This is less than that predicted by simply dividing
the GBP product by NG
1
. The compensation network controls
the bandwidth to a lower value, while providing the full slew
rate at the output and an exceptional distortion performance
due to increased loop gain at frequencies below NG
1
Z
O
.
Using this low-gain inverting compensation, along with the
differential structure for the circuit shown on the front page of
this data sheet, gives a significant reduction in harmonic
distortion. The measured distortion at 2V
PP
output does not
rise above –95dB until frequencies > 20MHz are applied.
The Typical Characteristics show the exceptional bandwidth con-
trol possible using this technique at low inverting gains. Figure 6
repeats the measured results with the test circuit shown.
The compensation capacitors, C
S
and C
F
, are set by targeting a
high-frequency noise gain of 21 and using equations 4 through
6. This approach allows relatively low inverting gain applications
to use the full slew rate and low input noise of the OPA847.
LOW-NOISE FIGURE,
HIGH DYNAMIC RANGE AMPLIFIER
The low input noise voltage of the OPA847 and its very high
2-tone, 3rd-order intermodulation intercept can be used to
good advantage as a fixed-gain amplifier. While input noise
figures in the 10dB range (for a matched 50
input) are
easily achieved with just the OPA847, Figure 7 illustrates a
technique to reduce the noise figure even further, while
providing a broadband, high-gain HF amplifier stage using
two stages of the OPA847.
FIGURE 6. Low-Gain Inverting Performance.
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
LOW GAIN INVERTING BANDWIDTH
Frequency (MHz)
N
1
10
100
1000
G = –8
G = –4
G = –2
G = –1
V
O
= 0.2V
PP
R
F
750
C
S
OPA847
V
O
V
I
C
F
R
G
0
Source
V
DIS
+5V
–5V
FIGURE 7. Very High Dynamic Range HF Amplifier.
OPA847
10pF
P
I
1.6pF
6.19k
750
1.5k
200
30.1
420
4.3dB
Noise
Figure
1:2
50
Source
P
O
> 55dBm
intercept
to 30MHz
OPA847
46pF
Input match
set by this
feedback path
Overall Gain = 35.6dB
P
P
I
+5V
–5V
+5V
–5V
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA847ID | 功能描述:高速運算放大器 Wdebnd Ult-Lo Noise 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 |
| OPA847IDBVR | 功能描述:高速運算放大器 Wdebnd Ult-Lo Noise 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 |
| OPA847IDBVRG4 | 功能描述:高速運算放大器 Wdebnd Ult-Lo Noise 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 |
| OPA847IDBVT | 功能描述:高速運算放大器 Wdebnd Ult-Lo Noise 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 |
| OPA847IDBVT | 制造商:Texas Instruments 功能描述:OP AMP WIDEBAND VFB SOT-23-6 847 |
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