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參數資料
| 型號： | AD8031A |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 2.7 V, 800 uA, 80 MHz Rail-to-Rail I/O Amplifiers |
| 中文描述： | 2.7伏，800微安，80 MHz的軌到軌輸入/輸出放大器 |
| 文件頁數： | 13/16頁 |
| 文件大小： | 247K |
| 代理商： | AD8031A |
AD8031/AD8032
–13–
REV. B
Output Overdrive Recovery
Output overdrive of an amplifier occurs when the amplifier
attempts to drive the output voltage to a level outside its normal
range. After the overdrive condition is removed, the amplifier
must recover to normal operation in a reasonable amount of
time. As shown in Figure 40, the AD8031/AD8032 recover
within 100 ns from negative overdrive and within 80 ns from
positive overdrive.
V
S
=
6
2.5V
V
IN
=
6
2.5V
R
L
= +1k
V
TO GND
100ns
1V
R
F
= R
G
= 2k
V
V
OUT
R
L
R
F
50
V
R
G
V
IN
Figure 40. Overdrive Recovery
Driving Capacitive Loads
Capacitive loads interact with an op amp’s output impedance to
create an extra delay in the feedback path. This reduces circuit
stability, and can cause unwanted ringing and oscillation. A
given value of capacitance causes much less ringing when the
amplifier is used with a higher noise gain.
The capacitive load drive of the AD8031/AD8032 can be in-
creased by adding a low valued resistor in series with the capaci-
tive load. Introducing a series resistor tends to isolate the
capacitive load from the feedback loop, thereby, diminishing its
influence. Figure 41 shows the effects of a series resistor on
capacitive drive for varying voltage gains. As the closed-loop
gain is increased, the larger phase margin allows for larger ca-
pacitive loads with less overshoot. Adding a series resistor at
lower closed-loop gains accomplishes the same effect. For large
capacitive loads, the frequency response of the amplifier will be
dominated by the roll-off of the series resistor and capacitive
load.
1000
10
100
0
1
4
C
CLOSED-LOOP GAIN – V/V
2
3
R
G
C
L
R
F
V
OUT
V
= +5V
200mV STEP
WITH 30% OVERSHOOT
R
S
= 20
V
R
S
= 0
V
, 5
V
1
5
R
S
= 20
V
R
S
R
S
= 0
V
R
S
= 5
V
Figure 41. Capacitive Load Drive vs. Closed-Loop Gain
Output Stage, Open-Loop Gain and Distortion vs. Clearance
from Power Supply
The AD8031 features a rail-to-rail output stage. The output
transistors operate as common emitter amplifiers, providing the
output drive current as well as a large portion of the amplifier’s
open-loop gain.
Q37
R29
300
V
Q47
Q21
Q20
Q51
Q27
Q68
Q44
Q42
Q48
Q49
Q50
Q43
C5
1.5pF
I4
25
m
A
V
OUT
Q38
I1
25
m
A
DIFFERENTIAL
DRIVE
FROM
INPUT STAGE
I5
25
m
A
I2
25
m
A
C9
5pF
Figure 39. Output Stage Simplified Schematic
The output voltage limit depends on how much current the
output transistors are required to source or sink. For applica-
tions with very low drive requirements (a unity gain follower
driving another amplifier input, for instance), the AD8031 typi-
cally swings within 20 mV of either voltage supply. As the re-
quired current load increases, the saturation output voltage will
increase linearly as I
LOAD
×
R
C
, where I
LOAD
is the required load
current and R
C
is the output transistor collector resistance. For
the AD8031, the collector resistances for both output transistors
are typically 25
. As the current load exceeds the rated output
current of 15 mA, the amount of base drive current required to
drive the output transistor into saturation will reach its limit,
and the amplifier’s output swing will rapidly decrease.
The open-loop gain of the AD8031 decreases approximately
linearly with load resistance and also depends on the output
voltage. Open-loop gain stays constant to within 250 mV of the
positive power supply, 150 mV of the negative power supply and
then decreases as the output transistors are driven further into
saturation.
The distortion performance of the AD8031/AD8032 amplifiers
differs from conventional amplifiers. Typically an amplifier’s
distortion performance degrades as the output voltage ampli-
tude increases.
Used as a unity gain follower, the AD8031/AD8032 output will
exhibit more distortion in the peak output voltage region around
V
CC
–0.7 V. This unusual distortion characteristic is caused by
the input stage architecture and is discussed in detail in the
section covering “Input Stage Operation.”
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PDF描述 |
|---|---|
| AD8031AN | 2.7 V, 800 uA, 80 MHz Rail-to-Rail I/O Amplifiers |
| AD8031AR | 2.7 V, 800 uA, 80 MHz Rail-to-Rail I/O Amplifiers |
| AD8031AR-REEL7 | 2.7 V, 800 uA, 80 MHz Rail-to-Rail I/O Amplifiers |
| AD8031ART-REEL | 2.7 V, 800 uA, 80 MHz Rail-to-Rail I/O Amplifiers |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8031AN | 制造商:Rochester Electronics LLC 功能描述:PDIP SINGLE LOW POWER OP AMP - Bulk 制造商:Analog Devices 功能描述:IC SM AMP LOW POWER RRI/O |
| AD8031ANZ | 功能描述:IC OPAMP VF R-R LP LDIST 8DIP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產品培訓模塊:Differential Circuit Design Techniques for Communication Applications 標準包裝:1 系列:- 放大器類型:RF/IF 差分 電路數:1 輸出類型:差分 轉換速率:9800 V/µs 增益帶寬積:- -3db帶寬:2.9GHz 電流 - 輸入偏壓:3µA 電壓 - 輸入偏移:- 電流 - 電源:40mA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):3 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-VQFN 裸露焊盤，CSP 供應商設備封裝:16-LFCSP-VQ 包裝:剪切帶 (CT) 產品目錄頁面:551 (CN2011-ZH PDF) 其它名稱:ADL5561ACPZ-R7CT |
| AD8031ANZ | 制造商:Analog Devices 功能描述:Operational Amplifier (Op-Amp) IC |
| AD8031AR | 功能描述:IC OPAMP VF R-R LP LDIST 8SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:100 系列:- 放大器類型:通用 電路數:1 輸出類型:- 轉換速率:0.2 V/µs 增益帶寬積:- -3db帶寬:- 電流 - 輸入偏壓:100pA 電壓 - 輸入偏移:30µV 電流 - 電源:380µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):±2 V ~ 18 V 工作溫度:0°C ~ 70°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-SO 包裝:管件 |
| AD8031AR-EBZ | 功能描述:BOARD EVAL FOR AD8031AR RoHS:是 類別:編程器，開發系統 >> 評估板 - 運算放大器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- |
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