EL2126CSZ-T13 [INTERSIL]
Ultra-Low Noise, Low Power, Wideband Amplifier; 超低噪声，低功耗，宽带放大器
| 型号： | EL2126CSZ-T13 |
| 厂家： | 
Intersil |
| 描述： | Ultra-Low Noise, Low Power, Wideband Amplifier |
| 文件： | 总15页 (文件大小：275K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EL2126
®
Data Sheet
May 9, 2005
FN7046.2
Ultra-Low Noise, Low Power, Wideband
Amplifier
Features
• Voltage noise of only 1.3nV/√Hz
• Current noise of only 1.2pA/√Hz
• 200µV offset voltage
The EL2126 is an ultra-low noise, wideband amplifier that
runs on half the supply current of competitive parts. It is
intended for use in systems such as ultrasound imaging
where a very small signal needs to be amplified by a large
amount without adding significant noise. Its low power
dissipation enables it to be packaged in the tiny SOT-23
package, which further helps systems where many input
channels create both space and power dissipation problems.
• 100MHz -3dB BW for A = 10
V
• Very low supply current - 4.7mA
• SOT-23 package
• ±2.5V to ±15V operation
The EL2126 is stable for gains of 10 and greater and uses
traditional voltage feedback. This allows the use of reactive
elements in the feedback loop, a common requirement for
many filter topologies. It operates from ±2.5V to ±15V
supplies and is available in the 5-pin SOT-23 and 8-pin SO
packages.
• Pb-Free available (RoHS compliant)
Applications
• Ultrasound input amplifiers
• Wideband instrumentation
• Communication equipment
• AGC & PLL active filters
• Wideband sensors
The EL2126 is fabricated in Elantec’s proprietary
complementary bipolar process, and is specified for
operation over the full -40°C to +85°C temperature range.
Pinouts
EL2126
(5-PIN SOT-23)
TOP VIEW
Ordering Information
PART NUMBER
PACKAGE
TAPE & REEL PKG. DWG. #
EL2126CW-T7
5-Pin SOT-23
7” (3K pcs)
MDP0038
MDP0038
MDP0027
MDP0027
MDP0027
MDP0027
OUT
VS-
IN+
1
2
3
5
4
VS+
IN-
EL2126CW-T7A 5-Pin SOT-23
7” (250 pcs)
EL2126CS
8-Pin SO
8-Pin SO
8-Pin SO
-
7”
13”
-
+
-
EL2126CS-T7
EL2126CS-T13
EL2126CSZ
(See Note)
8-Pin SO
(Pb-free)
EL2126
(8-PIN SO)
TOP VIEW
EL2126CSZ-T7
(See Note)
8-Pin SO
(Pb-free)
7”
MDP0027
MDP0027
NC
IN-
1
2
3
4
8
7
6
5
NC
EL2126CSZ-T13
(See Note)
8-Pin SO
(Pb-free)
13”
VS+
OUT
NC
-
NOTE: Intersil Pb-free products employ special Pb-free material sets;
molding compounds/die attach materials and 100% matte tin plate
termination finish, which are RoHS compliant and compatible with
both SnPb and Pb-free soldering operations. Intersil Pb-free products
are MSL classified at Pb-free peak reflow temperatures that meet or
exceed the Pb-free requirements of IPC/JEDEC J STD-020.
+
IN+
VS-
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-352-6832 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2004, 2005. All Rights Reserved
1
All other trademarks mentioned are the property of their respective owners.
EL2126
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . .-40°C to +85°C
Storage Temperature. . . . . . . . . . . . . . . . . . . . . . . .-60°C to +150°C
Maximum Die Junction Temperature . . . . . . . . . . . . . . . . . . . +150°C
Absolute Maximum Ratings (T = 25°C)
A
V + to V - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33V
S
S
Continuous Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . 40mA
Any Input . . . . . . . . . . . . . . . . . . . . . . . . . . V + - 0.3V to V - + 0.3V
S
S
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Curves
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests
are at the specified temperature and are pulsed tests, therefore: T = T = T
A
J
C
Electrical Specifications V + = +5V, V - = -5V, T = 25°C, R = 180Ω, R = 20Ω, R = 500Ω unless otherwise specified.
S
S
A
F
G
L
PARAMETER
DESCRIPTION
CONDITIONS
MIN
TYP
0.2
17
MAX
UNIT
DC PERFORMANCE
V
Input Offset Voltage (SO8)
2
3
mV
mV
OS
Input Offset Voltage (SOT23-5)
T
Offset Voltage Temperature
Coefficient
µV/°C
CVOS
I
I
Input Bias Current
-10
-7
µA
µA
B
Input Bias Current Offset
0.06
0.013
0.6
OS
T
Input Bias Current Temperature
Coefficient
µA/°C
CIB
C
Input Capacitance
Open Loop Gain
2.2
87
pF
dB
dB
IN
A
V
= -2.5V to +2.5V
O
80
80
VOL
PSRR
Power Supply Rejection Ratio
(Note 1)
100
CMRR
CMIR
Common Mode Rejection Ratio
Common Mode Input Range
Positive Output Voltage Swing
Negative Output Voltage Swing
Positive Output Voltage Swing
Negative Output Voltage Swing
at CMIR
75
-4.6
3.8
106
dB
V
3.8
-3.9
-3.2
V
V
V
V
No load, R = 1kΩ
3.8
-4
V
OUTH
OUTL
OUTH2
OUTL2
OUT
F
No load, R = 1kΩ
V
F
R
= 100Ω
= 100Ω
3.2
80
3.45
-3.5
100
V
L
L
R
V
I
Output Short Circuit Current
(Note 2)
mA
I
Supply Current
4.7
5.5
mA
SY
AC PERFORMANCE - R = 20Ω, C = 3pF
G
L
BW
-3dB Bandwidth, R = 500Ω
100
17
MHz
MHz
MHz
dB
L
BW ±0.1dB
BW ±1dB
Peaking
SR
±0.1dB Bandwidth, R = 500Ω
L
±1dB Bandwidth, R = 500Ω
80
L
Peaking, R = 500Ω
0.6
110
2.8
-7
L
Slew Rate
V
= 2V , measured at 20% to 80%
PP
80
V/µs
%
OUT
OS
Overshoot, 4Vpk-pk Output Square Positive
Wave
Negative
%
t
Settling Time to 0.1% of ±1V Pulse
Voltage Noise Spectral Density
Current Noise Spectral Density
51
ns
S
V
1.3
1.2
nV/√Hz
pA/√Hz
N
I
N
2
EL2126
Electrical Specifications V + = +5V, V - = -5V, T = 25°C, R = 180Ω, R = 20Ω, R = 500Ω unless otherwise specified. (Continued)
S
S
A
F
G
L
PARAMETER
HD2
DESCRIPTION
CONDITIONS
MIN
TYP
-70
MAX
UNIT
dBc
2nd Harmonic Distortion (Note 3)
3rd Harmonic Distortion (Note 3)
HD3
-70
dBc
NOTES:
1. Measured by moving the supplies from ±4V to ±6V
2. Pulse test only and using a 10Ω load
3. Frequency = 1MHz, V
OUT
= 2Vpk-pk, into 500Ω and 5pF load
Electrical Specifications V + = +15V, V - = -15V, T = 25°C, R = 180Ω, R = 20Ω, R = 500Ω unless otherwise specified.
S
S
A
F
G
L
PARAMETER
DESCRIPTION
CONDITIONS
MIN
TYP
MAX
UNIT
DC PERFORMANCE
V
Input Offset Voltage (SO8)
0.5
3
3
mV
mV
OS
Input Offset Voltage (SOT23-5)
T
Offset Voltage Temperature
Coefficient
4.5
µV/°C
CVOS
I
I
Input Bias Current
-10
-7
µA
µA
B
Input Bias Current Offset
0.12
0.016
0.7
OS
T
Input Bias Current Temperature
Coefficient
µA/°C
CIB
C
Input Capacitance
Open Loop Gain
2.2
90
80
pF
dB
dB
IN
A
80
65
VOL
PSRR
Power Supply Rejection Ratio
(Note 1)
CMRR
CMIR
Common Mode Rejection Ratio
Common Mode Input Range
Positive Output Voltage Swing
Negative Output Voltage Swing
Positive Output Voltage Swing
Negative Output Voltage Swing
at CMIR
70
85
dB
V
-14.6
13.6
13.8
-13.7
-9.5
V
V
V
V
No load, R = 1kΩ
13.7
-13.8
11.2
-10.3
220
V
OUTH
OUTL
OUTH2
OUTL2
OUT
F
No load, R = 1kΩ
V
F
R
R
= 100Ω, R = 1kΩ
10.2
140
V
L
L
F
= 100Ω, R = 1kΩ
V
F
I
Output Short Circuit Current
(Note 2)
mA
I
Supply Current
5
6
mA
SY
AC PERFORMANCE - R = 20Ω, C = 3pF
G
L
BW
-3dB Bandwidth, R = 500Ω
135
26
MHz
MHz
MHz
dB
L
BW ±0.1dB
BW ±1dB
Peaking
SR
±0.1dB Bandwidth, R = 500Ω
L
±1dB Bandwidth, R = 500Ω
60
L
Peaking, R = 500Ω
2.1
150
L
Slew Rate (±2.5V Square Wave,
Measured 25%-75%)
130
V/µS
OS
Overshoot, 4Vpk-pk Output Square Positive
1.6
-4.4
48
%
%
Wave
Negative
T
Settling Time to 0.1% of ±1V Pulse
Voltage Noise Spectral Density
ns
S
V
1.4
nV/√Hz
N
3
EL2126
Electrical Specifications V + = +15V, V - = -15V, T = 25°C, R = 180Ω, R = 20Ω, R = 500Ω unless otherwise specified. (Continued)
S
S
A
F
G
L
PARAMETER
DESCRIPTION
CONDITIONS
MIN
TYP
1.1
MAX
UNIT
pA/√Hz
dBc
I
Current Noise Spectral Density
N
HD2
HD3
2nd Harmonic Distortion (Note 3)
3rd Harmonic Distortion (Note 3)
-72
-73
dBc
NOTES:
1. Measured by moving the supplies from ±13.5V to ±16.5V
2. Pulse test only and using a 10Ω load
3. Frequency = 1MHz, V
OUT
= 2Vpk-pk, into 500Ω and 5pF load
4
EL2126
Typical Performance Curves
Non-Inverting Frequency Response for Various R
Non-Inverting Frequency Response for Various R
F
F
10
6
10
6
V
A
=±5V
V =±15V
S
S
R =1kΩ
F
=10
A =10
V
V
R =1kΩ
F
C =5pF
R =500Ω
C =5pF
L
L
L
R =500Ω
R =500Ω
R =500Ω
L
F
F
2
2
-2
-6
-10
-2
-6
-10
R =180Ω
R =180Ω
F
F
R =100Ω
F
R =100Ω
F
1M
10M
100M
1M
10M
Frequency (Hz)
100M
Frequency (Hz)
Inverting Frequency Response for Various R
Inverting Frequency Response for Various R
F
F
8
4
8
4
R =1kΩ
V
A
=±5V
V =±15V
S
F
S
R =500Ω
R =1kΩ
F
F
=-10
A =-10
V
V
R =500Ω
C =5pF
R =500Ω
C =5pF
L
F
L
L
R =500Ω
R =350Ω
L
F
R =350Ω
F
0
0
R =200Ω
F
R =200Ω
F
-4
-8
-12
-4
-8
-12
R =100Ω
R =100Ω
F
F
1M
10M
100M
1M
10M
100M
Frequency (Hz)
Frequency (Hz)
Non-Inverting Frequency Response for Various Gain
Non-Inverting Frequency Response for Various Gain
10
6
10
6
V
R
=±5V
V =±15V
S
S
=20Ω
R =20Ω
G
G
R =500Ω
C =5pF
R =500Ω
L
L
L
C =5pF
L
A =10
V
2
2
A =10
V
A =20
A =20
V
V
-2
-6
-10
-2
-6
-10
A =50
V
A =50
V
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
5
EL2126
Typical Performance Curves (Continued)
Inverting Frequency Response for Various Gain
8
Inverting Frequency Response for Various R
F
8
4
V
=±15V
V
=±5V
S
S
C =5pF
R
C =5pF
R =35Ω
L
L
G
=20Ω
4
0
G
0
A =-10
V
A =-10
V
-4
-4
-8
-12
A =-50
V
A =-50
V
A =-20
V
A =-20
V
-8
-12
1M
10M
100M
1M
10M
100M
Frequency (Hz)
Frequency (Hz)
Non-Inverting Frequency Response for Various
Output Signal Levels
Non-Inverting Frequency Response for Various
Output Signal Levels
8
4
10
6
V
=±5V
V =±15V
S
S
L
L
F
C =5pF
R =500Ω
R =180Ω
A
C =5pF
L
V
=30mV
PP
R =500Ω
O
L
R =180Ω
F
V
=500mV
PP
O
=10
A =10
V
V
V
=500mV
V =30mV
O PP
0
2
O
PP
V
=1V
PP
O
-4
-8
-12
-2
-6
-10
V
=5V
V
=10V
O
PP
O
PP
V
=2.5V
V
=5V
O
PP
O
PP
V
=1V
V =2.5V
O PP
O
PP
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
Inverting Frequency Response for Various Output
Signal Levels
Inverting Frequency Response for Various Output
Signal Levels
8
4
8
4
V
=±5V
V =±15V
S
S
V
=500mV
=30mV
V =500mV
O
C =5pF
R =500Ω
R =350Ω
C =5pF
O
PP
PP
V =30mV
O
L
L
F
L
R =500Ω
L
V
R =200Ω
O
PP
PP
F
V
=1V
PP
O
V
=1V
PP
A
=10
A
=10
O
V
V
0
0
V
=3.4V
V =3.4V
O PP
O
PP
-4
-8
-12
-4
-8
-12
V
=2.5V
V =2.5V
O PP
O
PP
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
6
EL2126
Typical Performance Curves (Continued)
Non-Inverting Frequency Response for Various C
10
Non-Inverting Frequency Response for Various C
L
L
10
6
V
=±5V
V =±15V
S
S
F
R =150Ω
A
R =500Ω
R =180Ω
F
C =28pF
C =11pF
L
L
=10
A =10
V
6
2
C =28pF
V
L
R =500Ω
L
L
C =16pF
L
C =11pF
C =16pF
L
L
2
C =5pF
C =5pF
L
L
-2
-6
-10
-2
C =1.2pF
L
C =1pF
L
-6
-10
1M
1M
10M
100M
10M
Frequency (Hz)
100M
Frequency (Hz)
Inverting Frequency Response for Various C
Inverting Frequency Response for Various C
L
L
8
4
8
4
V
=±5V
V =±15V
S
S
C =28pF
L
C =28pF
L
R =350Ω
R =500Ω
A
R =200Ω
F
F
R =500Ω
C =16pF
L
V
L
V
L
C =16pF
=-10
A
=-10
L
0
0
C =11pF
L
C=11pF
L
-4
-8
-4
-8
-12
C =5pF
L
C =5pF
L
C =1.2pF
L
C
=1.2pF
L
-12
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
Open Loop Gain/Phase
Gain
Supply Current vs Supply Voltage
100
80
60
40
20
0
250
150
Phase
50
0.6/div
-50
-150
-250
V
=±5V
S
0
10k
100k
1M
10M
100M
1G
0
1.5/div
Frequency (Hz)
Supply Voltage (V)
7
EL2126
Typical Performance Curves (Continued)
Bandwidth vs V
Peaking vs V
s
s
160
140
120
100
80
3.0
2.5
2.0
1.5
1.0
0.5
0
V
R
=±5V
V
R
=±5V
S
S
A =-10
=20Ω
=20Ω
V
G
G
R =500Ω
C =5pF
R =500Ω
C =5pF
L
L
L
L
A =10
V
A =10
V
A =-20
V
60
40
A =-20
V
A =-10
V
A =-50
V
20
A =50
V
0
0
2
4
6
8
10
12
14
16
0
2
4
6
8
10
12
14
16
±V (V)
±Supply Voltage (V)
S
Small Signal Step Response
Large Signal Step Response
R =180Ω
V
V
=±5V
F
S
R
=20Ω
=2V
G
O
PP
20mV/div
0.5V/div
R =180Ω
F
G
R
=20Ω
V
V
=±5V
S
=100mV
O
10ns/div
10ns/div
1MHz Harmonic Distortion vs Output Swing
1MHz Harmonic Distortion vs Output Swing
-40
-50
-30
V
V
=±5V
V
V
=±5V
S
S
=2V
=2V
O
P-P
-40
-50
O
P-P
R =180Ω
A
R =500Ω
R =180Ω
A =10
R =500Ω
F
F
V
L
2nd HD
=10
2nd HD
3rd HD
V
-60
L
-60
-70
-70
-80
-80
3rd HD
-90
-90
-100
-100
0
1
2
3
4
5
6
7
8
0
5
10
15
20
25
V
(V
)
V
(V )
OUT P-P
OUT P-P
8
EL2126
Typical Performance Curves (Continued)
Total Harmonic Distortion vs Frequency
-20
Noise vs Frequency
10
V
V
=±5V
=2V
S
O
-30
-40
-50
-60
-70
-80
-90
P-P
I
, V =±5V
S
N
V
, V =±15V
S
N
V
, V =±5V
S
N
I
, V =±15V
S
N
1
10
1k
10k
100k
1M
10M
100M
100
1k
10k
100k
Frequency (Hz)
Frequency (Hz)
Settling Time vs Accuracy
Group Delay vs Frequency
70
60
50
40
30
20
10
0
16
12
8
V
=±5V
S
R =500Ω
L
A =10
V
4
A =-10
V
0
-4
0.1
1.0
10.0
1M
10M
Frequency (Hz)
100M
400M
Accuracy (%)
CMRR vs Frequency
PSRR vs Frequency
-10
-30
110
90
70
50
30
10
V
=±5V
S
PSRR-
-50
-70
PSRR+
-90
-110
10
100
1k
10k 100k 1M
Frequency (Hz)
10M 100M
10k
100k
1M
10M
200M
Frequency (Hz)
9
EL2126
Typical Performance Curves (Continued)
Closed Loop Output Impedance vs Frequency
Bandwidth and Peaking vs Temperature
120
3.5
3
100
10
V =±5V
S
V
=±5V
S
100
80
60
40
20
0
2.5
2
Bandwidth
1.5
1
1
Peaking
0.5
0
0.1
0.01
-0.5
10k
100k
1M
10M
100M
-40
0
40
80
120
160
Frequency (Hz)
Temperature
Slew Rate vs Swing
Supply Current vs Temperature
220
200
180
160
140
120
100
80
5.2
5.1
5
15V
-
SR
V
=±15V
S
15V
SR
+
5V
-
SR
V
=±5V
S
4.9
4.8
5V
+
SR
60
-1
1
3
5
7
9
11
13
15
-50
0
50
100
150
V
Swing (V
)
Die Temperature (°C)
OUT
PP
Offset Voltage vs Temperature
CMRR vs Temperature
1
0
120
110
100
90
V
=±5V
S
V
=±5V
S
V
=±15V
S
-1
-2
80
-50
-50
0
50
Die Temperature (°C)
100
150
0
50
100
150
Die Temperature (°C)
10
EL2126
Typical Performance Curves (Continued)
PSRR vs Temperature
110
Positive Output Swing vs Temperature
4.05
106
4
3.95
3.9
V
=±5V
S
102
98
94
90
86
82
V
=±5V
S
V
=±15V
0
S
3.85
3.8
-50
50
Die Temperature (°C)
100
150
150
150
-50
0
50
Die Temperature (°C)
100
150
150
150
Positive Output Swing vs Temperature
Negative Output Swing vs Temperature
13.85
13.8
-3.9
-3.95
-4
V
=±15V
13.75
13.7
S
V
=±5V
-4.05
-4.1
S
-4.15
-4.2
13.65
13.6
-50
-4.25
0
50
Die Temperature (°C)
100
-50
0
50
Die Temperature (°C)
100
Negative Output Swing vs Temperature
Slew Rate vs Temperature
-13.76
-13.78
-13.8
102
100
98
V
=±5V
S
96
V
=±15V
S
94
92
90
-13.82
88
-50
-50
0
50
Die Temperature (°C)
100
0
50
Die Temperature (°C)
100
11
EL2126
Typical Performance Curves (Continued)
Slew Rate vs Temperature
155
Positive Loaded Output Swing vs Temperature
3.52
150
3.5
3.48
3.46
3.44
V
=±5V
S
V
=±15V
S
145
140
135
V
=2V
PP
O
-50
0
50
Die Temperature (°C)
100
150
150
150
-50
0
50
Die Temperature (°C)
100
150
Positive Loaded Output Swing vs Temperature
Negative Loaded Output Swing vs Temperature
11.8
11.6
11.4
11.2
11
-3.35
-3.4
V
=±15V
S
-3.45
-3.5
V
=±5V
S
3.55
10.8
10.6
-50
-3.6
-50
0
50
Die Temperature (°C)
100
0
50
Die Temperature (°C)
100
150
Package Power Dissipation vs Ambient Temperature
JEDEC JESD51-3 Low Effective Thermal Conductivity
Test Board
Negative Loaded Output Swing vs Temperature
-9.4
-9.6
1.2
1
781mW
488mW
-9.8
V
=±15V
0.8
0.6
0.4
0.2
0
S
-10
-10.2
-10.4
-10.6
-50
0
50
100
0
25
50
75 85 100
125
150
Die Temperature (°C)
Ambient Temperature (°C)
Package Power Dissipation vs Ambient Temperature
JEDEC JESD51-7 High Effective Thermal Conductivity
Test Board
1.8
1.6
1.4
1.2
1
1.136W
543mW
0.8
0.6
0.4
0.2
0
0
25
50
75 85 100
125
150
Ambient Temperature (°C)
12
EL2126
Pin Descriptions
EL2126CW
EL2126CS
(5-PIN SOT-23)
(8-PIN SO)
PIN NAME
PIN FUNCTION
EQUIVALENT CIRCUIT
1
6
VOUT
Output
V
+
S
V
OUT
Circuit 1
2
3
4
3
VS-
Supply
Input
VINA+
V
+
S
V
+
V -
IN
IN
V
-
S
Circuit 2
4
5
2
7
VINA-
VS+
Input
Reference Circuit 2
Supply
13
EL2126
Noise Calculations
Applications Information
The primary application for the EL2126 is to amplify very
small signals. To maintain the proper signal-to-noise ratio, it
is essential to minimize noise contribution from the amplifier.
Figure 2 below shows all the noise sources for all the
components around the amplifier.
Product Description
The EL2126 is an ultra-low noise, wideband monolithic
operational amplifier built on Elantec's proprietary high
speed complementary bipolar process. It features 1.3nV/√Hz
input voltage noise, 200µV typical offset voltage, and 73dB
THD. It is intended for use in systems such as ultrasound
imaging where very small signals are needed to be
R
3
V
V
V
N
IN
R3
+
-
I
+
V
ON
N
amplified. The EL2126 also has excellent DC specifications:
200µV V , 22µA IB, 0.4µA I , and 106dB CMRR. These
specifications allow the EL2126 to be used in DC-sensitive
applications such as difference amplifiers.
OS OS
V
R1
R
1
I
-
V
R2
N
Gain-Bandwidth Product
R
2
The EL2126 has a gain-bandwidth product of 650MHz at
±5V. For gains less than 20, higher-order poles in the
amplifier's transfer function contribute to even higher closed-
loop bandwidths. For example, the EL2126 has a -3dB
bandwidth of 100MHz at a gain of 10 and decreases to
33MHz at gain of 20. It is important to note that the extra
bandwidth at lower gain does not come at the expenses of
stability. Even though the EL2126 is designed for gain ≥ 10.
With external compensation, the device can also operate at
lower gain settings. The RC network shown in Figure 1
reduces the feedback gain at high frequency and thus
maintains the amplifier stability. R values must be less than
RF divided by 9 and 1 divided by 2πRC must be less than
200MHz.
FIGURE 2.
V
is the amplifier input voltage noise
N
I + is the amplifier positive input current noise
N
I - is the amplifier negative input current noise
N
V
is the thermal noise associated with each resistor:
RX
V
=
4kTRx
RX
where:
k is Boltzmann's constant = 1.380658 x 10
-23
R
F
R
T is temperature in degrees Kelvin (273+ °C)
-
V
OUT
C
+
The total noise due to the amplifier seen at the output of the
amplifier can be calculated by using the following equation
(Figure 3).
V
IN
FIGURE 1.
As the equation shows, to keep noise at a minimum, small
resistor values should be used. At higher amplifier gain
configuration where R is reduced, the noise due to IN-, R ,
Choice of Feedback Resistor, RF
2
2
and R decreases and the noise caused by IN+, VN, and R
1
3
The feedback resistor forms a pole with the input
starts to dominate. Because noise is summed in a root-
mean-squares method, noise sources smaller than 25% of
the largest noise source can be ignored. This can greatly
simplify the formula and make noise calculation much easier
to calculate.
capacitance. As this pole becomes larger, phase margin is
reduced. This increases ringing in the time domain and
peaking in the frequency domain. Therefore, RF has some
maximum value which should not be exceeded for optimum
performance. If a large value of RF must be used, a small
capacitor in the few pF range in parallel with RF can help to
reduce this ringing and peaking at the expense of reducing
the bandwidth. Frequency response curves for various RF
values are shown in the typical performance curves section
of this data sheet.
Output Drive Capability
The EL2126 is designed to drive low impedance load. It can
easily drive 6V
signal into a 100Ω load. This high output
drive capability makes the EL2126 an ideal choice for RF, IF,
P-P
2
2
2
2
R
R
R
R
2
2
2
2
2
1
1
1
1
------
V
=
BW × VN × 1 + ------ + IN- × R + IN+ × R × 1 + ------ + 4 × K × T × R + 4 × K × T × R
×
+ 4 × K × T × R × 1 + ------
3
ON
1
3
1
2
R
2
R
R
R
2
2
2
FIGURE 3.
14
EL2126
and video applications. Furthermore, the EL2126 is current-
limited at the output, allowing it to withstand momentary
short to ground. However, the power dissipation with output-
shorted cannot exceed the power dissipation capability of
the package.
where pin 4 (V -) is connected to the ground plane, a single
4.7µF tantalum capacitor in parallel with a 0.1µF ceramic
S
capacitor across pins 7 (V +) and pin 4 (V -) will suffice.
S
S
For good AC performance, parasitic capacitance should be
kept to a minimum. Ground plane construction again should
be used. Small chip resistors are recommended to minimize
series inductance. Use of sockets should be avoided since
they add parasitic inductance and capacitance which will
result in additional peaking and overshoot.
Driving Cables and Capacitive Loads
Although the EL2126 is designed to drive low impedance
load, capacitive loads will decreases the amplifier's phase
margin. As shown in the performance curves, capacitive load
can result in peaking, overshoot and possible oscillation. For
optimum AC performance, capacitive loads should be
reduced as much as possible or isolated with a series
resistor between 5Ω to 20Ω. When driving coaxial cables,
double termination is always recommended for reflection-
free performance. When properly terminated, the
capacitance of the coaxial cable will not add to the capacitive
load seen by the amplifier.
Supply Voltage Range and Single Supply
Operation
The EL2126 has been designed to operate with supply
voltage range of ±2.5V to ±15V. With a single supply, the
EL2126 will operate from +5V to +30V. Pins 4 and 7 are the
power supply pins. The positive power supply is connected
to pin 7. When used in single supply mode, pin 4 is
connected to ground. When used in dual supply mode, the
negative power supply is connected to pin 4.
Power Supply Bypassing And Printed Circuit
Board Layout
As the power supply voltage decreases from +30V to +5V, it
becomes necessary to pay special attention to the input
voltage range. The EL2126 has an input voltage range of
0.4V from the negative supply to 1.2V from the positive
supply. So, for example, on a single +5V supply, the EL2126
has an input voltage range which spans from 0.4V to 3.8V.
The output range of the EL2126 is also quite large, on a +5V
supply, it swings from 0.4V to 3.8V.
As with any high frequency devices, good printed circuit
board layout is essential for optimum performance. Ground
plane construction is highly recommended. Lead lengths
should be kept as short as possible. The power supply pins
must be closely bypassed to reduce the risk of oscillation.
The combination of a 4.7µF tantalum capacitor in parallel
with 0.1µF ceramic capacitor has been proven to work well
when placed at each supply pin. For single supply operation,
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
15
相关型号：
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OP-AMP, 3000uV OFFSET-MAX, 80MHz BAND WIDTH, PDSO5, GREEN, PLASTIC, SOT-23, 5 PIN
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EL2126CWZ-T7A
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