參數(shù)資料
型號: THS4081CDR
廠商: TEXAS INSTRUMENTS INC
元件分類: 音頻/視頻放大
英文描述: 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
封裝: GREEN, PLASTIC, SOIC-8
文件頁數(shù): 4/32頁
文件大?。?/td> 841K
代理商: THS4081CDR
THS4081, THS4082
175MHz LOW POWER HIGHSPEED AMPLIFIERS
SLOS274D DECEMBER 1999 REVISED JUNE 2001
12
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
APPLICATION INFORMATION
noise calculations and noise figure (continued)
_
+
RF
RS
RG
eRg
eRf
eRs
en
IN+
Noiseless
IN
eni
eno
Figure 39. Noise Model
The total equivalent input noise density (eni) is calculated by using the following equation:
e
ni +
en
2
) IN )
R
S
2
) IN–
R
F
R
G
2
) 4kTRs ) 4kT RF RG
Where:
k = Boltzmann’s constant = 1.380658
× 1023
T = Temperature in degrees Kelvin (273 +
°C)
RF || RG = Parallel resistance of RF and RG
To get the equivalent output noise of the amplifier, just multiply the equivalent input noise density (eni) by the
overall amplifier gain (AV).
eno + eni AV + eni 1 )
R
F
R
G
(noninverting case)
As the previous equations show, to keep noise at a minimum, small value resistors should be used. As the
closed-loop gain is increased (by reducing RG), the input noise is reduced considerably because of the parallel
resistance term. This leads to the general conclusion that the most dominant noise sources are the source
resistor (RS) and the internal amplifier noise voltage (en). Because noise is summed in a root-mean-squares
method, noise sources smaller than 25% of the largest noise source can be effectively ignored. This can greatly
simplify the formula and make noise calculations much easier to calculate.
For more information on noise analysis, please refer to the Noise Analysis section in Operational Amplifier
Circuits Applications Report (literature number SLVA043).
相關PDF資料
PDF描述
THS4081CD 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
THS4081IDGNR 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
THS4081IDGN 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
THS4081IDR 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
THS4081ID 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
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