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參數(shù)資料
| 型號： | OP484ES |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 運動控制電子 |
| 英文描述： | Precision Rail-to-Rail Input & Output Operational Amplifiers |
| 中文描述： | QUAD OP-AMP, 300 uV OFFSET-MAX, 4.25 MHz BAND WIDTH, PDSO14 |
| 封裝： | MS-012AB, SOIC-14 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大小： | 522K |
| 代理商： | OP484ES |
REV. 0
–12–
OP184/OP284/OP484
Referring to the op amp noise model circuit configuration illus-
trated in Figure 45, the expression for an amplifier’s total
equivalent input noise voltage for a source resistance level R
S
is
given by:
[
e
nT
=
2
e
nR
(
)
2
+
i
nOA
×
R
(
)
2
]
+
e
nOA
(
)
2
,
units in
V
Hz
where R
S
= 2R = Effective, or equivalent, circuit source
resistance,
(
e
nOA
)
2
= Op amp equivalent input noise voltage spectral
power (1 Hz BW),
(
i
nOA
)
2
= Op amp equivalent input noise current spectral
power (1 Hz BW),
(
e
nR
)
2
= Source resistance thermal noise voltage power =
(4kTR),
k
= Boltzmann’s constant = 1.38
×
10
–23
J/K, and
T
= Ambient temperature of the circuit, in Kelvin, =
273.15 + T
A
(
°
C)
i
NOA
e
NR
e
NOA
R
"NOISELESS"
i
NOA
e
NR
R
"NOISELESS"
IDEAL
NOISELESS
OP AMP
R
S
= 2R
Figure 45. Op Amp Noise Circuit Model Used to
Determine Total Circuit Equivalent Input Noise Voltage
and Noise Figure
As a design aid, Figure 46 illustrates the total equivalent input
noise of the OP284 and the total thermal noise of a resistor for
comparison. Note that for source resistance less than 1 k
, the
equivalent input noise voltage of the OP284 is dominant.
TOTAL SOURCE RESISTANCE, R
S
–
100
100
E
√
H
1k
10k
100k
10
1
OP284 TOTAL
EQUIVALENT NOISE
RESISTOR THERMAL
NOISE ONLY
FREQUENCY = 1kHz
T
A
= +25
°
C
Figure 46. OP284 Total Noise vs. Source Resistance
Since circuit SNR is the critical parameter in the final analysis,
the noise behavior of a circuit is often expressed in terms of its
noise figure, NF. Noise figure is defined as the ratio of a
circuit’s output signal-to-noise to its input signal-to-noise. An
expression of a circuit’s NF in dB, and in terms of the opera-
tional amplifier’s voltage and current noise parameters defined
previously, is given by:
NF
(
dB
)
=
10 log 1
+
e
nOA
(
)
2
+
i
nOA
R
S
(
e
nRS
(
)
2
)
2
where
NF
(
dB
) = Noise figure of the circuit, expressed in dB,
R
S
= Effective, or equivalent, source resistance presented
to amplifier,
(
e
nOA
)
2
= OP284 noise voltage spectral power (1 Hz BW),
(
i
nOA
)
2
= OP284 noise current spectral power (1 Hz BW),
(
e
nRS
)
2
= Source resistance thermal noise voltage power
= (4kTR
S
),
Circuit noise figure is straightforward to calculate because the
signal level in the application is not required to determine it.
However, many designers using NF calculations as the basis for
achieving optimum SNR believe that low noise figure is equal to
low total noise. In fact, the opposite is true, as illustrated in
Figure 47. Here, the noise figure of the OP284 is expressed as a
function of the source resistance level. Note that the lowest
noise figure for the OP284 occurs at a source resistance level of
10 k
. However, Figure 46 shows that this source resistance
level and the OP284 generate approximately 14 nV/
√
Hz
of total
equivalent circuit noise. Signal levels in the application would
invariably be increased to maximize circuit SNR—not an option
in low voltage, single supply applications.
TOTAL SOURCE RESISTANCE, R
S
–
6
100
N
1k
10k
100k
4
2
0
9
10
8
7
5
3
1
FREQUENCY = 1kHz
T
A
= +25
°
C
Figure 47. OP284 Noise Figure vs. Source Resistance
In single supply applications, therefore, it is recommended for
optimum circuit SNR to choose an operational amplifier with
the lowest equivalent input noise voltage and to choose source
resistance levels consistent in maintaining low total circuit noise.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| OP484ES-REEL | 功能描述:IC OPAMP GP R-R 4.25MHZ 14SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:2,500 系列:Excalibur™ 放大器類型:J-FET 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:45 V/µs 增益帶寬積:10MHz -3db帶寬:- 電流 - 輸入偏壓:20pA 電壓 - 輸入偏移:490µV 電流 - 電源:1.7mA 電流 - 輸出 / 通道:48mA 電壓 - 電源，單路/雙路(±):4.5 V ~ 38 V，±2.25 V ~ 19 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:8-SOIC 包裝:帶卷 (TR) |
| OP484ESZ | 功能描述:IC OPAMP GP R-R 4.25MHZ 14SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:2,500 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:- 轉(zhuǎn)換速率:0.6 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:45nA 電壓 - 輸入偏移:2000µV 電流 - 電源:1.4mA 電流 - 輸出 / 通道:40mA 電壓 - 電源，單路/雙路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:14-TSSOP 包裝:帶卷 (TR) 其它名稱:LM324ADTBR2G-NDLM324ADTBR2GOSTR |
| OP484ESZ | 制造商:Analog Devices 功能描述:Operational Amplifier (Op-Amp) IC |
| OP484ESZ-REEL | 功能描述:IC OPAMP GP R-R 4.25MHZ 14SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:2,500 系列:Excalibur™ 放大器類型:J-FET 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:45 V/µs 增益帶寬積:10MHz -3db帶寬:- 電流 - 輸入偏壓:20pA 電壓 - 輸入偏移:490µV 電流 - 電源:1.7mA 電流 - 輸出 / 通道:48mA 電壓 - 電源，單路/雙路(±):4.5 V ~ 38 V，±2.25 V ~ 19 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:8-SOIC 包裝:帶卷 (TR) |
| OP484F | 制造商:Analog Devices 功能描述: |
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