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參數(shù)資料
| 型號： | MAX4120 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Quad, 400MHz, Low-Power, Current Feedback Amplifiers(四路,270MHz,低功率,電流反饋運放) |
| 中文描述： | 單/雙/四路、400MHz、低功耗、電流反饋放大器 |
| 文件頁數(shù)： | 11/12頁 |
| 文件大?。?/td> | 181K |
| 代理商： | MAX4120 |
DC and Noise Errors
There are several major error sources to consider in
any operational amplifier. These apply equally to the
MAX4112/MAX4113/MAX4117/MAX4118. Offset-error
terms are given by the equation below. Voltage and
current noise errors are root-square summed and
therefore computed separately. In Figure 3, the total
output offset voltage is determined by:
a) The input offset voltage (V
OS
) times the closed-loop
gain (1 + R
F
/ R
G
).
b) The positive input bias current (I
B+
) times the source
resistor (R
S
) (usually 50
or 75
), plus the negative
input bias current (I
B-
), times the parallel combina-
tion of R
G
and R
F
. In current-mode feedback ampli-
fiers, the input bias currents may flow into or out of
the device. For this reason, there is no benefit to
matching the resistance at both inputs.
The equation for total DC error is:
[
c) The total output-referred noise voltage is:
The MAX4112/MAX4117 have a very low, 2nV/
√
Hz
noise
voltage. The current noise at the positive input (i
n+
) is
13pA/
√
Hz
, and the current noise at the inverting input is
14pA/
√
Hz
.
An example of the DC error calculations, using the
MAX4112 typical data and the typical operating circuit
where R
F
= R
G
= 500
(R
F
||
R
G
= 250
) and R
S
= 50
,
gives the following:
V
OUT
= (3.5 x 10
-6
x 50 + 3.5 x 10
-6
x 250 + 10
-3
) (1 + 1)
V
OUT
= 4.1mV
Calculating total output noise in a similar manner yields:
With a 200MHz system bandwidth, this calculates to
56.6μV
RMS
(approximately 340μVp-p, choosing the six-
sigma value).
Resistor T ypes
Surface-mount resistors are the best choice for high-
frequency circuits. They are of similar material to metal-
film resistors, but are deposited using a thick-film
process in a flat, linear manner that minimizes induc-
tance. Their small size and lack of leads also minimizes
parasitic inductance and capacitance, yielding more
predictable performance.
Metal-film resistors with leads are manufactured using
a thin-film process where resistive material is deposited
in a spiral layer around a ceramic rod. Although the
materials used are noninductive, the spiral winding pre-
sents a small inductance (about 5nH) that may have an
adverse effect on high-frequency circuits.
Carbon composition resistors with leads are manufac-
tured by pouring the resistor material into a mold. This
process yields relatively low-inductance resistors that
are very useful in high-frequency applications, although
they tend to cost more and have more thermal noise
than other types. The ability of carbon composition
resistors to self-heal after a large current overload
makes them useful in high-power RF applications.
For general-purpose use, surface-mount metal-film
resistors seem to have the best overall performance for
low cost, low inductance, and low noise.
V ideo Line Driver
The MAX4112/MAX4113/MAX4117/MAX4118 are opti-
mized (gain flatness) to drive coaxial transmission lines
when the cable is terminated at both ends, as shown in
Figure 4. Cable frequency response can cause varia-
tions in the flatness of the signal.
Driving Capac itive Loads
The MAX4112/MAX4113/MAX4117/MAX4118 are opti-
mized for AC performance. They are not designed to
drive highly capacitive loads. Reactive loads decrease
phase margin and can produce excessive ringing and
oscillation. Figure 5 shows a circuit that eliminates this
problem. The small (usually 5
to 20
) isolation resis-
tor, R
S
, placed before the reactive load prevents ring-
ing and oscillation. At higher capacitive loads, AC
performance is controlled by the interaction of the load
capacitance and isolation resistor.
e
x
x
x
x
x
e
nV
Hz
n OUT
(
n OUT
(
)
)
/
=
(
)
+
+
=
1 1
13 10
50
14 10
250
2 10
4
12
2
12
2
9
2
e
R
R
i
R
)
i
R
)
R
e
n OUT
(
F
G
n
S
n
F
G
n
)
||
=
+
(
[
]
+
(
[
]
+
(
)
+
1
2
2
2
V
OUT
||
=
(
)
+
(
)
(
)
+
]
+
I
R
I
R
R
V
R
R
B
S
B
F
G
OS
F
G
1
M
S ingle/Dual, 500MHz, Low-Power,
Current-Mode Feedbac k Amplifiers
______________________________________________________________________________________
11
R
G
I
B
-
I
B
+
V
OUT
R
F
R
S
MAX4112
MAX4113
MAX4117
MAX4118
Figure 3. Output Offset Voltage
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX4120EEE | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Single/Dual/Quad, 400MHz, Low-Power, Current Feedback Amplifiers |
| MAX4120ESD | 功能描述:高速運算放大器 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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MAX4120ESD+ | 功能描述:高速運算放大器 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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MAX4120ESD+T | 功能描述:高速運算放大器 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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MAX4120ESD-T | 功能描述:高速運算放大器 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(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
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