EL2126CS-T7 [ELANTEC]
Operational Amplifier, 1 Func, 2000uV Offset-Max, BIPolar, PDSO8, SO-8;
| 型号： | EL2126CS-T7 |
| 厂家： | 
ELANTEC SEMICONDUCTOR |
| 描述： | Operational Amplifier, 1 Func, 2000uV Offset-Max, BIPolar, PDSO8, SO-8 光电二极管 |
| 文件： | 总16页 (文件大小：223K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Features
General Description
• Voltage noise of only 1.3nV/√Hz
• Current noise of only 1.2pA/√Hz
• 200µV offset voltage
The EL2126C 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 SOT23
package, which further helps systems where many input channels cre-
ate both space and power dissipation problems.
• 100MHz -3dB BW for A =10
V
• Very low supply current - 4.7mA
• SOT23 package
•
2.5V to 15V operation
The EL2126C is stable for gains of 10 and greater and uses traditional
voltage feedback. This allows the use of reactive elements in the feed-
back loop, a common requirement for many filter topologies. It
operates from 2.5V to 15V supplies and is available in 5-pin SOT23
and 8-pin SO packages.
Applications
• Ultrasound input amplifiers
• Wideband instrumentation
• Communication equipment
• AGC & PLL active filters
• Wideband sensors
The EL2126C is fabricated in Elantec’s proprietary complementary
bipolar process, and is specified for operation over the full -40°C to
+85°C temperature range.
Ordering Information
Tape &
Part No
EL2126CW-T7
EL2126CW-T13
EL2126CS
Package
5-Pin SOT23
5-Pin SOT23
8-Pin SO
Reel
Outline #
MDP0038
MDP0038
MDP0027
MDP0027
MDP0027
7”
13”
-
Connection Diagrams
EL2126CS-T7
EL2126CS-T13
8-Pin SO
7”
8-Pin SO
13”
NC
IN-
IN+
VS-
1
2
3
4
8
7
6
5
NC
OUT
VS-
IN+
1
2
3
5
4
VS+
IN-
VS+
OUT
NC
-
+
+
-
EL2126C
(5-Pin SOT23)
EL2126C
(8-Pin SO)
Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
© 2002 Elantec Semiconductor, Inc.
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Absolute Maximum Ratings (T = 25°C)
A
VS+ to VS-
33V
40mA
Operating Temperature
-40°C to +85°C
-60°C to +150°C
+150°C
Continuous Output Current
Any Input
Storage Temperature
VS+ - 0.3V to VS- + 0.3V
See Curves
Maximum Die Junction Temperature
Power Dissipation
Important Note:
All parameters having Min/Max specifications are guaranteed. Typ values are for information purposes only. Unless otherwise noted, all tests are at the
specified temperature and are pulsed tests, therefore: TJ = TC = TA
Electrical Characteristics
VS+ = +5V, VS- = -5V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified.
Parameter
DC Performance
VOS
Description
Conditions
Min
Typ
Max
Unit
Input Offset Voltage (SO8)
Input Offset Voltage (SOT23-5)
Offset Voltage Temperature Coefficient
Input Bias Current
0.2
2
3
mV
mV
µV/°C
µA
µA
µA/°C
pF
TCVOS
IB
17
-7
-10
IOS
Input Bias Current Offset
Input Bias Current Temperature Coefficient
Input Capacitance
0.06
0.013
2.2
0.6
TCIB
CIN
AVOL
PSRR
CMRR
CMIR
VOUTH
VOUTL
VOUTH2
VOUTL2
IOUT
Open Loop Gain
VO = -2.5V to +2.5V
80
80
87
dB
[1]
Power Supply Rejection Ratio
100
106
dB
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
dB
-4.6
3.8
3.8
-3.9
-3.2
5.5
V
No load, RF = 1kΩ
No load, RF = 1kΩ
RL = 100Ω
3.8
-4
V
V
3.2
80
3.45
-3.5
100
4.7
V
RL = 100Ω
V
[2]
Output Short Circuit Current
mA
mA
ISY
Supply Current
AC Performance - RG = 20Ω, CL = 3pF
BW
-3dB Bandwidth, RL = 500Ω
0.1dB Bandwidth, RL = 500Ω
1dB Bandwidth, RL = 500Ω
Peaking, RL = 500Ω
100
17
MHz
MHz
MHz
dB
BW 0.1dB
BW 1dB
Peaking
SR
80
0.6
110
2.8
-7
Slew Rate
V
OUT = 2VPP, measured at 20% to 80%
80
V/µs
%
OS
Overshoot, 4Vpk-pk Output Square Wave
Positive
Negative
%
tS
Settling Time to 0.1% of 1V Pulse
Voltage Noise Spectral Density
Current Noise Spectral Density
51
ns
VN
IN
1.3
1.2
-70
-70
nV/√Hz
pA/√Hz
dBc
[3]
HD2
HD3
2nd Harmonic Distortion
[3]
3rd Harmonic Distortion
dBc
1. Measured by moving the supplies from 4V to 6V
2. Pulse test only and using a 10Ω load
3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load
2
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Electrical Characteristics
VS+ = +15V, VS- = -15V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified.
Parameter
DC Performance
VOS
Description
Conditions
Min
Typ
Max
Unit
Input Offset Voltage (SO8)
Input Offset Voltage (SOT23-5)
Offset Voltage Temperature Coefficient
Input Bias Current
0.5
3
3
mV
mV
µV/°C
µA
µA
µA/°C
pF
TCVOS
IB
4.5
-7
-10
IOS
Input Bias Current Offset
Input Bias Current Temperature Coefficient
Input Capacitance
0.12
0.016
2.2
90
0.7
TCIB
CIN
AVOL
PSRR
CMRR
CMIR
VOUTH
VOUTL
VOUTH2
VOUTL2
IOUT
Open Loop Gain
80
65
dB
[1]
Power Supply Rejection Ratio
80
dB
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
-14.6
13.6
13.8
-13.7
-9.5
6
V
No load, RF = 1kΩ
No load, RF = 1kΩ
RL = 100Ω, RF = 1kΩ
RL = 100Ω, RF = 1kΩ
13.7
-13.8
11.2
-10.3
220
5
V
V
10.2
140
V
V
[2]
Output Short Circuit Current
mA
mA
ISY
Supply Current
AC Performance - RG = 20Ω, CL = 3pF
BW
-3dB Bandwidth, RL = 500Ω
0.1dB Bandwidth, RL = 500Ω
1dB Bandwidth, RL = 500Ω
Peaking, RL = 500Ω
135
26
MHz
MHz
MHz
dB
BW 0.1dB
BW 1dB
Peaking
SR
60
2.1
150
Slew Rate ( 2.5V Square Wave, Measured
25%-75%)
130
V/µS
OS
Overshoot, 4Vpk-pk Output Square Wave
Positive
1.6
-4.4
48
%
%
Negative
TS
Settling Time to 0.1% of 1V Pulse
Voltage Noise Spectral Density
Current Noise Spectral Density
ns
VN
1.4
1.1
-72
-73
nV/√Hz
pA/√Hz
dBc
IN
[3]
HD2
HD3
2nd Harmonic Distortion
[3]
3rd Harmonic Distortion
dBc
1. Measured by moving the supplies from 13.5V to 16.5V
2. Pulse test only and using a 10Ω load
3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load
3
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Non-Inverting Frequency Response for Various R
Non-Inverting Frequency Response for Various R
F
F
10
6
10
6
V = 5V
V
V = 15V
S
V
C =5pF
L
R =500Ω
L
S
R =1kΩ
F
A =10
A =10
R =1kΩ
F
C =5pF
L
R =500Ω
L
R =500Ω
F
R =500Ω
F
2
2
-2
-6
-10
-2
-6
-10
R =180Ω
R =180Ω
F
F
R =100Ω
F
R =100Ω
F
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
Inverting Frequency Response for Various R
Inverting Frequency Response for Various R
F
F
8
4
8
4
R =1kΩ
F
V = 5V
S
V = 15V
S
R =500Ω
R =1kΩ
F
F
A =-10
A =-10
V
V
R =500Ω
C =5pF
L
C =5pF
L
F
R =500Ω
R =500Ω
L
L
R =350Ω
F
R =350Ω
F
0
0
R =200Ω
F
R =200Ω
F
-4
-8
-12
-4
-8
-12
R =100Ω
F
R =100Ω
F
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
Non-Inverting Frequency Response for Various Gain
Non-Inverting Frequency Response for Various Gain
10
6
10
6
V = 5V
G
V = 15V
S
G
S
R =20Ω
R =20Ω
R =500Ω
R =500Ω
L
L
C =5pF
C =5pF
L
L
A =10
V
2
2
A =10
V
A =20
V
A =20
V
-2
-6
-10
-2
-6
-10
A =50
V
A =50
V
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
4
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Inverting Frequency Response for Various Gain
Inverting Frequency Response for Various R
F
8
8
4
V = 5V
L
R =35Ω
G
V = 15V
S
L
R =20Ω
G
S
C =5pF
C =5pF
4
0
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
C =5pF
C =5pF
L
R =180Ω
F
A =10
V
L
L
V =30mV
PP
R =500Ω
R =500Ω
O
L
R =180Ω
F
V =500mV
O
PP
A =10
V
V =500mV
V =30mV
O PP
0
2
O
PP
V =1V
O
PP
-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
O
V =2.5V
O PP
PP
1M
10M
100M
1M
10M
Frequency (Hz)
100M
Frequency (Hz)
Inverting Frequency Response for Various Output Signal
Levels
Inverting Frequency Response for Various Output Signal
Levels
8
4
8
4
V = 5V
S
V = 15V
S
V =500mV
V =500mV
O PP
C =5pF
L
C =5pF
L
O
PP
R =500Ω
R =500Ω
L
L
V =30mV
O
V =30mV
O
PP
PP
R =350Ω
R =200Ω
F
F
V =1V
O
PP
V =1V
O
PP
A =10
A =10
V
V
0
0
V =3.4V
V =3.4V
O PP
O
PP
-4
-8
-12
-4
-8
-12
V =2.5V
O
V =2.5V
O
PP
PP
1M
10M
100M
1M
10M
100M
Frequency (Hz)
Frequency (Hz)
5
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Non-Inverting Frequency Response for Various C
Non-Inverting Frequency Response for Various C
L
L
10
6
10
6
V = 5V
F
V = 15V
S
F
S
R =150Ω
R =180Ω
C =28pF
C =11pF
L
L
A =10
A =10
V
V
C =28pF
L
R =500Ω
R =500Ω
L
L
C =16pF
L
C =11pF
L
C =16pF
L
2
2
C =5pF
C =5pF
L
L
-2
-6
-10
-2
-6
-10
C =1.2pF
L
C =1pF
L
1M
10M
Frequency (Hz)
100M
1M
10M
Frequency (Hz)
100M
Inverting Frequency Response for Various C
Inverting Frequency Response for Various C
L
L
8
4
8
4
V = 5V
S
V = 15V
S
C =28pF
L
C =28pF
L
R =350Ω
R =200Ω
F
F
R =500Ω
R =500Ω
L
L
C =16pF
L
C =16pF
L
A =-10
A =-10
V
V
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
Supply Current vs Supply Voltage
100
80
60
40
20
0
250
150
Gain
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)
6
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
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 = 5V
S
G
V = 5V
S
G
A =-10
R =20Ω
R =20Ω
V
R =500Ω
R =500Ω
L
L
C =5pF
C =5pF
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
S
(V)
Supply Voltage (V)
Small Signal Step Response
Large Signal Step Response
R =180Ω V = 5V
F
S
R =20Ω
G
V =2V
O PP
20mV/div
0.5V/div
R =180Ω
F
R =20Ω
G
V = 5V
S
V =100mV
O
PP
10ns/div
10ns/div
1MHz Harmonic Distortion vs Output Swing
1MHz Harmonic Distortion vs Output Swing
-40
-50
-30
V = 5V
V = 5V
S
O P-P
S
V =2V
V =2V
O
P-P
-40
-50
R =180Ω
R =180Ω
F
F
2nd HD
A =10
A =10
V
V
2nd HD
3rd HD
R =500Ω
R =500Ω
L
L
-60
-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
OUT P-P
)
V
(V
OUT P-P
7
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Total Harmonic Distortion vs Frequency
Noise vs Frequency
-20
10
V = 5V
S
V =2V
O
P-P
-30
-40
-50
-60
-70
-80
-90
I , V = 5V
N
S
V , V = 15V
N
S
V , V = 5V
N
S
I , V = 15V
N
S
1
10
1k
10k
100k
1M
10M
100M
100
1k
Frequency (Hz)
10k
100k
400M
200M
Frequency (Hz)
Settling Time vs Accuracy
Group Delay vs Frequency
70
60
50
40
30
20
10
0
16
12
8
V = 5V
R =500Ω
L
S
A =10
V
S
O
P
-
P
4
A =-10
V
0
-4
1M
0.1
1.0
Accuracy (%)
10.0
10M
Frequency (Hz)
100M
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
10M 100M
10k
100k
1M
10M
Frequency (Hz)
Frequency (Hz)
8
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Closed Loop Output Impedance vs Frequency
Bandwidth and Peaking vs Temperature
120
100
80
60
40
20
0
3.5
3
100 V = 5V
S
V = 5V
S
2.5
2
10
1
Bandwidth
1.5
1
Peaking
0.5
0
0.1
0.01
10k
-0.5
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
)
PP
Die Temperature (°C)
OUT
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
100
150
0
50
100
150
Die Temperature (°C)
Die Temperature (°C)
9
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
PSRR vs Temperature
Positive Output Swing vs Temperature
110
4.05
4
106
V = 5V
S
102
98
94
90
86
82
3.95
3.9
3.85
3.8
V = 5V
S
V = 15V
S
-50
0
50
100
100
100
150
150
150
-50
0
50
Die Temperature (°C)
100
100
100
150
150
150
Die Temperature (°C)
Positive Output Swing vs Temperature
Negative Output Swing vs Temperature
13.85
13.8
-3.9
-3.95
-4
V = 15V
S
13.75
13.7
V = 5V
S
-4.05
-4.1
-4.15
-4.2
13.65
13.6
-50
-4.25
0
50
-50
0
50
Die Temperature (°C)
Die Temperature (°C)
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
0
50
Die Temperature (°C)
Die Temperature (°C)
10
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Slew Rate vs Temperature
Positive Loaded Output Swing vs Temperature
155
3.52
150
3.5
V = 5V
S
V = 15V
S
145
140
135
3.48
3.46
3.44
V =2V
O
PP
-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
100
150
Die Temperature (°C)
18 Negative Loaded Output Swing vs Temperature
Package Power Dissipation vs Ambient Temperature
JEDEC JESD51-3 Low Effective Thermal Conductivity Test Board
-9.4
1.2
1
-9.6
781mW
488mW
-9.8
-10
V = 15V
S
0.8
0.6
0.4
0.2
0
-10.2
-10.4
-10.6
-50
0
50
Die Temperature (°C)
100
0
25
50
75 85 100
125
150
Ambient Temperature (°C)
11
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Typical Performance Curves
Package Power Dissipation vs Ambient Temperature
JEDEC JESD51-7 High Effective Thermal Conductivity Test Board
1.8
1.6
1.4
1.136W
1.2
1
0.8
543mW
0.6
0.4
0.2
0
0
25
50
75 85 100
125
150
Ambient Temperature (°C)
12
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Pin Descriptions
EL2126CW
EL2126CS
(5-Pin SOT23)
(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
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
Applications Information
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.
Product Description
The EL2126C is an ultra-low noise, wideband mono-
lithic 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 amplified. The EL2126C also has excellent
Noise Calculations
The primary application for the EL2126C 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.
DC specifications: 200µV V , 22µA IB, 0.4µA I
,
OS
OS
and 106dB CMRR. These specifications allow the
EL2126C to be used in DC-sensitive applications such
as difference amplifiers.
Gain-Bandwidth Product
R
3
V
V
V
N
IN
R3
The EL2126C 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 EL2126C 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 EL2126C 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 stabil-
ity. R values must be less than RF divided by 9 and 1
+
-
I +
V
ON
N
V
R1
R
1
I -
N
V
R2
R
2
Figure 2.
divided by 2 RC must be less than 200MHz.
π
R
F
R
-
V
OUT
C
+
V
IN
Figure 1.
Choice of Feedback Resistor, RF
V
=
4kTRx
RX
The feedback resistor forms a pole with the input capac-
itance. 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
14
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
The total noise due to the amplifier seen at the output of
the amplifier can be calculated by using the following
equation:
2
2
2
2
R
R
R
R
1
2
2
2
2
2
1
1
1
------
------
------
------
V
=
BW × VN
×
1 +
+ IN- × R + IN+ × R
×
1 +
+ 4 × K × T × R + 4 × K × T × R
×
+ 4 × K × T × R ×
3
1 +
ON
1
3
1
2
R
2
R
2
R
2
R
2
As the above equation shows, to keep noise at a mini-
mum, small resistor values should be used. At higher
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 tanta-
lum capacitor in parallel with 0.1µF ceramic capacitor
has been proven to work well when placed at each sup-
amplifier gain configuration where R is reduced, the
2
noise due to IN-, R , and R decreases and the noise
2
1
caused by IN+, VN, and R starts to dominate. Because
3
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.
ply pin. For single supply operation, where pin 4 (V -) is
S
connected to the ground plane, a single 4.7µF tantalum
capacitor in parallel with a 0.1µF ceramic capacitor
across pins 7 (V +) and pin 4 (V -) will suffice.
S
S
Output Drive Capability
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 capaci-
tance which will result in additional peaking and
overshoot.
The EL2126C is designed to drive low impedance load.
It can easily drive 6V
signal into a 100Ω load. This
P-P
high output drive capability makes the EL2126C an
ideal choice for RF, IF, and video applications. Further-
more, the EL2126C 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.
Supply Voltage Range and Single Supply
Operation
The EL2126C has been designed to operate with supply
voltage range of 2.5V to 15V. With a single supply,
the EL2126C 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.
Driving Cables and Capacitive Loads
Although the EL2126C is designed to drive low imped-
ance load, capacitive loads will decreases the amplifier's
phase margin. As shown in the performance curves,
capacitive load can result in peaking, overshoot and pos-
sible 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 coax-
ial cable will not add to the capacitive load seen by the
amplifier.
As the power supply voltage decreases from +30V to
+5V, it becomes necessary to pay special attention to the
input voltage range. The EL2126C 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 sup-
ply, the EL2126C has an input voltage range which
spans from 0.4V to 3.8V. The output range of the
EL2126C is also quite large, on a +5V supply, it swings
from 0.4V to 3.8V.
Power Supply Bypassing And Printed Circuit
Board Layout
As with any high frequency devices, good printed circuit
board layout is essential for optimum performance.
15
EL2126C
Ultra-Low Noise, Low Power, Wideband Amplifier
General Disclaimer
Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes in the cir-
cuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any circuits described
herein and makes no representations that they are free from patent infringement.
WARNING - Life Support Policy
Elantec, Inc. products are not authorized for and should not be used
within Life Support Systems without the specific written consent of
Elantec, Inc. Life Support systems are equipment intended to sup-
port or sustain life and whose failure to perform when properly used
in accordance with instructions provided can be reasonably
Elantec Semiconductor, Inc.
675 Trade Zone Blvd.
Milpitas, CA 95035
Telephone: (408) 945-1323
(888) ELANTEC
expected to result in significant personal injury or death. Users con-
templating application of Elantec, Inc. Products in Life Support
Systems are requested to contact Elantec, Inc. factory headquarters
to establish suitable terms & conditions for these applications. Elan-
tec, Inc.’s warranty is limited to replacement of defective
components and does not cover injury to persons or property or
other consequential damages.
Fax:
(408) 945-9305
European Office: +44-118-977-6020
Japan Technical Center: +81-45-682-5820
Printed in U.S.A.
16
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