參數(shù)資料
型號(hào)： THS4271DGK
廠商： TEXAS INSTRUMENTS INC
元件分類(lèi)： 音頻／視頻放大
英文描述： 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8
封裝： GREEN, PLASTIC, MSOP-8
文件頁(yè)數(shù)： 14/48頁(yè)
文件大?。?/td> 1227K
代理商： THS4271DGK
_
+
THS4271
Rg
249
RT
130
100 pF
0.1
F
6.8
F
VS
5 V
50
Source
+
VI
100 pF
0.1
F
6.8
F
+
+VS
5 V
VO
CT
0.1
F
Rf
249
RM
61.9
499
www.ti.com
SLOS397F – JULY 2002 – REVISED OCTOBER 2009
WIDEBAND, INVERTING GAIN OPERATION
must be taken when dealing with low inverting gains,
as the resulting feedback resistor value can present a
Since
the
THS4271
and
THS4275
are
significant load to the amplifier output. For an
general-purpose,
wideband
voltage-feedback
inverting gain of 2, setting Rg to 49.9 for input
amplifiers,
several
familiar
operational
amplifier
matching eliminates the need for RM but requires a
applications circuits are available to the designer.
100-
feedback resistor. This has an advantage of
Figure 76 shows a typical inverting configuration
the noise gain becoming equal to 2 for a 50-
source
where the input and output impedances and noise
impedance—the same as the noninverting circuit in
gain from Figure 75 are retained in an inverting circuit
Figure 75. However, the amplifier output now sees
configuration. Inverting operation is one of the more
the 100-
feedback resistor in parallel with the
common
requirements
and
offers
several
external load. To eliminate this excessive loading, it is
performance benefits. The inverting configuration
preferable to increase both Rg and Rf, values, as
shows improved slew rates and distortion due to the
shown in Figure 76, and then achieve the input
pseudo-static voltage maintained on the inverting
matching impedance with a third resistor (RM) to
input.
ground. The total input impedance becomes the
parallel combination of Rg and RM.
The next major consideration is that the signal source
impedance becomes part of the noise gain equation
and hence influences the bandwidth. For example,
the RM value combines in parallel with the external
50-
source
impedance
(at
high
frequencies),
yielding an effective source impedance of 50
||
61.9
= 27.7 . This impedance is then added in
series with Rg for calculating the noise gain. The
result is 1.9 for Figure 76, as opposed to the 1.8 if RM
is eliminated. The bandwidth is lower for the gain of
–2 circuit, Figure 76 (NG=+1.9), than for the gain of
+2 circuit in Figure 75.
The last major consideration in inverting amplifier
design is setting the bias current cancellation resistor
on the noninverting input. If the resistance is set
equal to the total dc resistance looking out of the
Figure 76. Wideband, Inverting Gain
inverting terminal, the output dc error, due to the input
Configuration
bias currents, is reduced to (input offset current)
multiplied by Rf in Figure 76, the dc source
impedance looking out of the inverting terminal is 249
In the inverting configuration, some key design
|| (249 + 27.7 ) = 130 . To reduce the
considerations must be noted. One is that the gain
additional high-frequency noise introduced by the
resistor (Rg) becomes part of the signal channel input
resistor at the noninverting input, and power-supply
impedance. If the input impedance matching is
feedback, RT is bypassed with a capacitor to ground.
desired (which is beneficial whenever the signal is
coupled through a cable, twisted pair, long PCB
trace, or other transmission line conductors), Rg may
be set equal to the required termination value and Rf
adjusted to give the desired gain. However, care
Copyright 2002–2009, Texas Instruments Incorporated
21
Product Folder Link(s): THS4271 THS4275
相關(guān)PDF資料
PDF描述
THS4271DG4 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8
THS4271DGKRG4 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8
THS4271DGNRG4 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8
THS4271DRB VIDEO AMPLIFIER, PDSO8
THS4275DRB VIDEO AMPLIFIER, PDSO8
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
THS4271DGKG4 功能描述:高速運(yùn)算放大器 Super-Fast Ultra-Low Distortion RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
THS4271DGKR 功能描述:高速運(yùn)算放大器 Super-Fast Ultra-Low Distortion RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
THS4271DGKRG4 功能描述:高速運(yùn)算放大器 Super-Fast Ultra-Low Distortion RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
THS4271DGN 功能描述:高速運(yùn)算放大器 Super-Fast Ultra-Low Distortion RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
THS4271DGN 制造商:Texas Instruments 功能描述:IC SM OP-AMP HI-SPEED VFB
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