intersil EL2126 DATA SHEET

®

EL2126

FN7046.4Data Sheet May 2, 2007

Ultra-Low Noise, Low Power, Wideband
Amplifier

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.

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 Ld SOT-23 and 8 Ld SO
packages.

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 LD SOT-23)

TOP VIEW

Features

• Voltage noise of only 1.3nV/√Hz

• Current noise of only 1.2pA/√Hz

• 200µV offset voltage

• 100MHz -3dB BW for A

= 10

V

• Very low supply current - 4.7mA

• SOT-23 package

• ±2.5V to ±15V operation

• Pb-free plus anneal available (RoHS compliant)

Applications

• Ultrasound input amplifiers

• Wideband instrumentation

• Communication equipment

• AGC and PLL active filters

• Wideband sensors

OUT

VS-

NC

IN-

IN+

VS-

1

2

3

1

2

3

4

-+

EL2126

(8 LD SOIC)

TOP VIEW

-

+

5

VS+

4

IN-IN+

NC

8

VS+

7

OUT

6

NC

5

1

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-468-3774

| Intersil (and design) is a registered trademark of Intersil Americas Inc.

Copyright Intersil Americas Inc. 2002, 2005, 2007. All Rights Reserved

All other trademarks mentioned are the property of their respective owners.

Ordering Information

EL2126

PART

NUMBER

EL2126CW-T7 G -40 to +85 7” (3k pcs) 5 Ld SOT-23 MDP0038
EL2126CW-T7A G -40 to +85 7” (250 pcs) 5 Ld SOT-23 MDP0038
EL2126CS 2126CS -40 to +85 - 8 Ld SOIC (150 mil) MDP0027
EL2126CS-T7 2126CS -40 to +85 7” 8 Ld SOIC (150 mil) MDP0027
EL2126CS-T13 2126CS -40 to +85 13” 8 Ld SOIC (150 mil) MDP0027
EL2126CSZ ( Note) 2126CSZ -40 to +85 - 8 Ld SOIC (150 mil)

EL2126CSZ-T7 ( Note) 2126CSZ -40 to +85 7” 8 Ld SOIC (150 mil)

EL2126CSZ-T13 ( Note) 2126CSZ -40 to +85 13” 8 Ld SOIC (150 mil)

EL2126CWZ-T7 (Note) BAAH -40 to +85 7” 5 Ld SOT-23 (SC74)

EL2126CWZ-T7A (Note) BAAH -40 to +85 7” 5 Ld SOT-23 (SC74)

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.

PART

MARKING

TEMP RANGE

(°C) TAPE AND REEL PACKAGE PKG. DWG. #

MDP0027

(Pb-free)

MDP0027

(Pb-free)

MDP0027

(Pb-free)

P5.064

(1.65mm) (Green)

P5.064

(1.65mm) (Green)

2

FN7046.4

May 2, 2007

EL2126

Absolute Maximum Ratings Thermal Information

VS+ to VS-) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33V

Continuous Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . 40mA

Any Input . . . . . . . . . . . . . . . . . . . . . . . . . . . V

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: TJ = TC = T

+ -0.3V to VS- +0.3V

S

A

Operating Temperature . . . . . . . . . . . . . . . . . . . . . . .-40°C to +85°C

Storage Temperature. . . . . . . . . . . . . . . . . . . . . . . .-60°C to +150°C

Maximum Die Junction Temperature. . . . . . . . . . . . . . . . . . .+150°C

Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Curves

Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below

http://www.intersil.com/pbfree/Pb-FreeReflow.asp

Electrical Specifications V

+ = +5V, VS- = -5V, TA = +25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω Unless Otherwise Specified.

S

Parameter Description Conditions Min Typ Max Unit

DC PERFORMANCE

V

OS

Input Offset Voltage (SO8) 0.2 2 mV
Input Offset Voltage (SOT23-5) 3mV

T

CVOS

I

B

I

OS

T

CIB

C

IN

A

VOL

PSRR Power Supply Rejection Ratio

Offset Voltage Temperature

17 µV/°C

Coefficient
Input Bias Current -10 -7 µA
Input Bias Current Offset 0.06 0.6 µA
Input Bias Current Temperature

0.013 µA/°C

Coefficient
Input Capacitance 2.2 pF
Open Loop Gain VO = -2.5V to +2.5V 80 87 dB

80 100 dB

(Note 1)
CMRR Common Mode Rejection Ratio at CMIR 75 106 dB
CMIR Common Mode Input Range -4.6 3.8 V
V

OUTH

V

OUTL

V

OUTH2

V

OUTL2

I

OUT

I

SY

AC PERFORMANCE - R

BW -3dB Bandwidth, R
BW ±0.1dB ±0.1dB Bandwidth, R
BW ±1dB ±1dB Bandwidth, R
Peaking Peaking, R
SR Slew Rate V
OS Overshoot, 4V

t

S

Positive Output Voltage Swing No load, RF = 1kΩ 3.8 3.8 V

Negative Output Voltage Swing No load, RF = 1kΩ -4 -3.9 V

Positive Output Voltage Swing RL = 100Ω 3.2 3.45 V

Negative Output Voltage Swing RL = 100Ω -3.5 -3.2 V

Output Short Circuit Current

80 100 mA

(Note 2)

Supply Current 4.7 5.5 mA

= 20Ω, CL = 3pF

G

= 500Ω 100 MHz

L

= 500Ω 17 MHz

L

= 500Ω 80 MHz

L

= 500Ω 0.6 dB

L

Wave

Output Square

P-P

= 2V

OUT

Positive 2.8 %
Negative -7 %

, measured at 20% to 80% 80 110 V/µs

P-P

Settling Time to 0.1% of ±1V Pulse 51 ns

3

FN7046.4

May 2, 2007

EL2126

Electrical Specifications V

+ = +5V, VS- = -5V, TA = +25°C, RF = 180Ω, R

S

: , R

G

: Unless Otherwise Specified.

L

Parameter Description Conditions Min Typ Max Unit

V

N

I

N

Voltage Noise Spectral Density 1.3 nV/√Hz

Current Noise Spectral Density 1.2 pA/√Hz
HD2 2nd Harmonic Distortion (Note 3) -70 dBc
HD3 3rd Harmonic Distortion (Note 3) -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

= 2V

Electrical Specifications V

P-P

+ = +15V, VS- = -15V, TA = 25°C, R

S

: and 5pF load

: , R

F

= 20Ω, R

G

: unless otherwise specified.

L

Parameter Description Conditions Min Typ Max Unit
DC PERFORMANCE
V

OS

Input Offset Voltage (SO8) 0.5 3 mV
Input Offset Voltage (SOT23-5) 3mV

T

CVOS

Offset Voltage Temperature

4.5 µV/°C

Coefficient
I
I
T

B
OS

CIB

Input Bias Current -10 -7 µA

Input Bias Current Offset 0.12 0.7 µA

Input Bias Current Temperature

0.016 µA/°C

Coefficient
C

IN

A

VOL

PSRR Power Supply Rejection Ratio

Input Capacitance 2.2 pF

Open Loop Gain 80 90 dB

65 80 dB

(Note 4)
CMRR Common Mode Rejection Ratio at CMIR 70 85 dB
CMIR Common Mode Input Range -14.6 13.8 V
V

OUTH

V

OUTL

V

OUTH2

V

OUTL2

I

OUT

Positive Output Voltage Swing No load, R

Negative Output Voltage Swing No load, R

Positive Output Voltage Swing R

Negative Output Voltage Swing R

L
L

Output Short Circuit Current

: 13.6 13.7 V

F

: -13.8 -13.7 V

F

: , RF = 1k: 10.2 11.2 V
: , RF = 1k: -10.3 -9.5 V

140 220 mA

(Note 5)
I

SY

AC PERFORMANCE - R
BW -3dB Bandwidth, R
BW ±0.1dB ±0.1dB Bandwidth, R
BW ±1dB ±1dB Bandwidth, R
Peaking Peaking, R
SR Slew Rate (±2.5V Square Wave,

Supply Current 56mA

= 20: , CL = 3pF

G

: 135 MHz

L

: 26 MHz

L

: 60 MHz

L

: 2.1 dB

L

130 150 V/µS

Measured 25%-75%)
OS Overshoot, 4V

Wave

T

S

Settling Time to 0.1% of ±1V Pulse 48 ns

Output Square

P-P

Positive 1.6 %
Negative -4.4 %

4

FN7046.4

May 2, 2007

Electrical Specifications V

+ = +15V, VS- = -15V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified. (Continued)

S

Parameter Description Conditions Min Typ Max Unit

V

N

I

N

Voltage Noise Spectral Density 1.4 nV/√Hz

Current Noise Spectral Density 1.1 pA/√Hz
HD2 2nd Harmonic Distortion (Note 6) -72 dBc
HD3 3rd Harmonic Distortion (Note 6) -73 dBc

NOTES:

4. Measured by moving the supplies from ±13.5V to ±16.5V

5. Pulse test only and using a 10Ω load

6. Frequency = 1MHz, V

OUT

= 2V

, into 500Ω and 5pF load

P-P

Typical Performance Curves

10

VS = ±5V

= 10

A

V

C

= 5pF

6

L

RL = 500Ω

2

-2

-6

NORMALIZED GAIN (dB)

-10
1M 10M 100M

RF = 500Ω

RF = 180Ω

FREQUENCY (Hz)

RF = 1kΩ

RF = 100Ω

FIGURE 1. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

8

4

0

-4

10

VS = ±15V

= 10

A

V

C

= 5pF

6

L

RL = 500Ω

2

-2

-6

NORMALIZED GAIN (dB)

-10
1M 10M 100M

RF = 1kΩ

RF = 500Ω

RF = 180Ω

RF = 100Ω

FREQUENCY (Hz)

FIGURE 2. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

-8

NORMALIZED GAIN (dB)

-12
1M 10M 100M

FREQUENCY (Hz)

FIGURE 3. INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

5

FIGURE 4. INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

May 2, 2007

FN7046.4

Typical Performance Curves (Continued)

FIGURE 5. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS GAIN

FIGURE 7. INVERTING FREQUENCY RESPONSE FOR

VARIOUS GAIN

FIGURE 6. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS GAIN

FIGURE 8. INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

FIGURE 9. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS OUTPUT SIGNAL LEVELS

6

FIGURE 10. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS OUTPUT SIGNAL LEVELS

FN7046.4

May 2, 2007

Typical Performance Curves (Continued)

EL2126

8

VS = ±5V
CL = 5pF
RL = 500Ω

4

RF = 350Ω
AV = 10

0

-4

-8

NORMALIZED GAIN (dB)

-12
1M 10M 100M

VO = 1V

VO = 3.4V

VO = 2.5V

FREQUENCY (Hz)

PP

PP

PP

VO = 500mV

VO = 30mV

PP

PP

FIGURE 11. INVERTING FREQUENCY RESPONSE FOR

VARIOUS OUTPUT SIGNAL LEVELS

10

VS = ±5V
RF = 150Ω
AV = 10

6

RL = 500Ω

2

-2

-6

NORMALIZED GAIN (dB)

CL = 28pF

CL = 16pFCL = 11pF

CL = 5pF

CL = 1pF

8

VS = ±15V
CL = 5pF
RL = 500Ω

4

RF = 200Ω
AV = 10

0

-4

-8

NORMALIZED GAIN (dB)

-12
1M 10M 100M

VO = 1V

VO = 3.4V

VO=2.5V

VO = 2.5V

FREQUENCY (Hz)

PP

P

PP

VO = 500mV

PP

VO = 30mV

PP

PP

FIGURE 12. INVERTING FREQUENCY RESPONSE FOR

VARIOUS OUTPUT SIGNAL LEVELS

10

VS = ±15V

6

2

-2

-6

NORMALIZED GAIN (dB)

RF = 180Ω
AV = 10
RL = 500Ω

CL = 28pF

CL = 16pF

CL = 5pF

CL = 11pF

CL = 1.2pF

-10
1M 10M 100M

FREQUENCY (Hz)

FIGURE 13. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

8

VS = ±5V
R

= 350Ω

F

RL = 500Ω

4

= -10

A

V

0

-4

-8

NORMALIZED GAIN (dB)

-12
1M 10M 100M

CL = 16pF

CL = 11pF

CL = 5pF

FREQUENCY (Hz)

CL = 28pF

CL = 1.2pF

FIGURE 15. INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

-10
1M 10M 100M

FREQUENCY (Hz)

FIGURE 14. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

8

VS = ±15V

= 200Ω

R

F

RL = 500Ω

4

A

= -10

V

0

-4

-8

NORMALIZED GAIN (dB)

-12
1M 10M 100M

CL = 16pF

CL=11p

CL = 11pF

FREQUENCY (Hz)

CL = 28pF

CL = 5pF

CL = 1.2pF

FIGURE 16. INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

7

FN7046.4

May 2, 2007

Typical Performance Curves (Continued)

EL2126

100

GAIN

80

60

40

OPEN LOOP GAIN (dB)

20

VS=±5V

0

10k 10M 1G

100k 100M1M

FREQUENCY (Hz)

PHASE

250

150

50

-50

-150

-250

0.6/DIV

OPEN LOOP PHASE (°)

SUPPLY CURRENT (mA)

0

0

1.5/DIV

SUPPLY VOLTAGE (V)

FIGURE 17. OPEN LOOP GAIN AND OPEN LOOP PHASE FIGURE 18. SUPPLY CURRENT vs SUPPLY VOLTAGE

160

VS = ±5V

140

RG = 20Ω
RL = 500Ω

120

CL = 5pF

100

80
60

-3dB BANDWIDTH

40
20

0

0246810 1416

AV = -10

AV = -20

AV = -50

12

±VS (V)

FIGURE 19. BANDWIDTH vs Vs

AV = 10

AV = -20

AV = 50

3.0
VS = ±5V
RG = 20Ω

2.5
RL = 500Ω

CL = 5pF

2.0

1.5

1.0

PEAKING (dB)

0.5

0

0246810 1416

AV = 10

AV = -10

12

±SUPPLY VOLTAGE (V)

FIGURE 20. PEAKING vs Vs

= 20Ω

VS = ±5V
V

= 2V

O

PP

10ns/DIV

0.5V/DIV

RF = 180Ω
R

G

FIGURE 21. LARGE SIGNAL STEP RESPONSE

8

20mV/DIV

RF = 180Ω
RG = 20Ω

VS = ±5V
VO = 100mV

PP

10ns/DIV

FIGURE 22. SMALL SIGNAL STEP RESPONSE

FN7046.4

May 2, 2007

Typical Performance Curves (Continued)

EL2126

-40
VS = ±5V
VO = 2V

-50

-60

-70

-80

-90

HARUMONIC DISTORTION (dBc)

-100

P-P

RF = 180Ω
AV = 10
RL = 500Ω

012345 78

3rd HD

V

OUT

2nd HD

(V

P-P

6

)

FIGURE 23. 1MHz HARMONIC DISTORTION vs OUTPUT

SWING

-20
VS = ±5V
VO = 2V

-30

-40

-50

-60

THD (dBc)

-70

-80

-90

1k 10k 100M

P-P

100k 1M 10M

FREQUENCY (Hz)

FIGURE 25. TOTAL HARMONIC DISTORTION vs FREQUENCY

-30
VS = ±5V
VO = 2V

HARMONIC DISTORTION (dBc)

-40

-50

-60

-70

-80

-90

-100

P-P

RF = 180Ω
AV = 10
RL = 500Ω

0 5 10 15 20 25

V

OUT

2nd HD

3rd HD

(V

)

P-P

FIGURE 24. 1MHz HARMONIC DISTORTION vs OUTPUT

SWING

10

(nV/√Hz)

N

(pA/√Hz), V

N

I

IN, VS = ±15V

1

10 100 10k 100k

IN, VS = ±5V

VN, VS = ±15V

VN, VS = ±5V

1k

FREQUENCY (Hz)

FIGURE 26. NOISE vs FREQUENCY

70

60

50

40

30

20

SETTLING TIME (ns)

10

0

0.1 1.0 10.0

V

V

S

=

V

S

=

±5V

V

S

=

±

1

5

V

ACCURACY (%)

S

=

±

5

V

,

V

O

=

5

V

P

-

±

1

5

V

,

V

, V

O

=

2

,

V

O

=

2

P

O

=

5

V

P

-

P

V

P

-

P

V

P

-

P

FIGURE 27. SETTLING TIME vs ACCURACY

9

16

VS = ±5V
R

= 500Ω

L

12

8

4

GROUP DELAY (ns)

0

-4
1M 10M 100M 400M

FREQUENCY (Hz)

AV = 10

AV = -10

FIGURE 28. GROUP DELAY vs FREQUENCY

FN7046.4

May 2, 2007

Typical Performance Curves (Continued)

EL2126

-10

-30

-50

-70

CMRR (dB)

-90

-110
10 1M 10M 100M

1k 100k100 10k

FREQUENCY (Hz)

FIGURE 29. CMRR vs FREQUENCY FIGURE 30. PSRR vs FREQUENCY

100

VS = ±5V

10

1

0.1

0.01

CLOSED LOOP OUTPUT IMPEDANCE (Ω)

10k 1M 100M

100k 10M

FREQUENCY (Hz)

FIGURE 31. CLOSED LOOP OUTPUT IMPEDANCE vs

FREQUENCY

110

90

70

50

PSRR (dB)

30

10

10k 100k 1M 10M 200M

120

100

80

60

BANDWIDTH (MHz)

40

20

PEAKING

0

-40 40 160

PSRR-

PSRR+

FREQUENCY (Hz)

BANDWIDTH

800120

TEMPERATURE (°C)

VS=±5V

VS = ±5V

3.5
3

2.5
2

1.5
1

0.5
0

-0.5

PEAKING (dB)

FIGURE 32. BANDWIDTH AND PEAKING vs TEMPERATURE

SLEW RATE (V/µs)

220
200
180
160
140
120
100

80
60

-1

15913

15VSR-

15VSR+

5VSR-

5VSR+

371115

V

SWING (VPP)

OUT

FIGURE 33. SLEW RATE vs SWING

10

5.2

5.1

5

(mA)

S

I

4.9

4.8

-50 0 100 15050
DIE TEMPERATURE (°C)

VS=±15V

VS=±5V

FIGURE 34. SUPPLY CURRENT vs TEMPERATURE

May 2, 2007

FN7046.4

11

Typical Performance Curves (Continued)

EL2126

-13.76

-13.78

(V)

OUTL

V

-13.8

-13.82

VS = ±15V

-50 0 100 15050
DIE TEMPERATURE (°C)

FIGURE 41. NEGATIVE OUTPUT SWING vs TEMPERATURE

155

150

VS = ±15V

145

SR (V/µs)

140

102

100

98

96

94

92

SLEW RATE (V/µs)

90

88

-50 0 100 15050

VS = ±5V

DIE TEMPERATURE (°C)

FIGURE 42. SLEW RATE vs TEMPERATURE

3.52

3.5

(V)

3.48

OUTH2

V

3.46

VS = ±5V

VO = 2V

135

-50 0 100 15050

PP

DIE TEMPERATURE (°C)

3.44

-50 0 100 15050
DIE TEMPERATURE (°C)

FIGURE 43. SLEW RATE vs TEMPERATURE FIGURE 44. POSITIVE LOADED OUTPUT SWING vs

TEMPERATURE

11.8

11.6

11.4

11.2

SR (V/µs)

11

10.8

10.6

-50 0 100 15050

VS = ±15V

DIE TEMPERATURE (°C)

FIGURE 45. POSITIVE LOADED OUTPUT SWING vs

TEMPERATURE

FIGURE 46. NEGATIVE LOADED OUTPUT SWING vs

-3.35

-3.4

-3.45

(V)

OUTL2

-3.5

V

3.55

-3.6

-50 0 100 15050

TEMPERATURE

VS = ±5V

DIE TEMPERATURE (°C)

12

FN7046.4

May 2, 2007

Typical Performance Curves (Continued)

-9.4

-9.6

-9.8

(V)

-10

OUTL2

V

-10.2

-10.4

-10.6

-50 0 100 15050

FIGURE 47. NEGATIVE LOADED OUTPUT SWING vs TEMPERATURE

JEDEC JESD51-3 LOW EFFECTIVE THERMAL
CONDUCTIVITY TEST BOARD

1.2

0.6

POWER DISSIPATION (W)--23374.88.7 2.17 0 8.0062 Tc(50)Tj-4758 -1.TD3.196.000901.6

0

0

AMBIENT Temperature (°C)

FIGURE 48. PACKAGE POWER DISSIP A TION vs AMBIENT

TEMPERATURE

VS=±15V

Die Temperature (°C)

FIGURE 49. PACKAGE POWER DISSIP A TION vs AMBIENT

TEMPERATURE

13

FN7046.4

May 2, 2007

Pin Descriptions

EL2126

EL2126CW

(5 Ld SOT-23)

EL2126CS

( 8 Ld SOIC) PIN NAME PIN FUNCTION EQUIVALENT CIRCUIT

1 6 VOUT Output

2 4 VS- Supply
3 3 VINA+ Input

4 2 VINA- Input Reference Circuit 2
5 7 VS+ Supply

VS+

Circuit 1

VS-

Circuit 2

VS+

V

OUT

VIN-VIN+

14

FN7046.4

May 2, 2007

EL2126

Applications Information

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
amplified. The EL2126 also has excellent DC specifications:
200µV V
specifications allow the EL2126 to be used in DC-sensitive
applications such as difference amplifiers.

Gain-Bandwidth Product

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 closed­loop 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 show n in Figure 50
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 2
200MHz.

Choice of Feedback Resistor, RF

The feedback resistor forms a pole with the input
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.

, 22µA IB, 0.4µA IOS, and 106dB CMRR. These

OS

πRC must be less than

R

F

R

C

V

IN

-

+

FIGURE 50.

V

OUT

Noise Calculations

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 51 shows all the noise sources for all the components
around the amplifier.

R

V

V
IN+ is the amplifier positive input current noise
I

N

VRX is the thermal noise associated with each resistor:

V

RX

where:

k is Boltzmann's constant = 1.380658 x 10
T is temperature in degrees Kelvin (273 + °C)

The total noise due to the amplifier seen at the output of the
amplifier can be calculated by using the Equation 2.

As the equation shows, to keep noise at a minimum, small
resistor values should be used. At higher amplifier gain
configuration where R
and R
starts to dominate. Because noise is summed in a root­mean-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.

3

IN

V

R3

IN+

IN-

V

N

+

-

V

R1

R

1

V

R2

R

2

V

ON

FIGURE 51.

is the amplifier input voltage noise

N

- is the amplifier negative input current noise

4kTRx=

-23

is reduced, the noise due to IN-, R2,

decreases and the noise caused by IN+, VN, and R3

1

2

(EQ. 1)

2

V

ON

⎛ ⎞

BW= VN21

×

⎜ ⎟
⎝ ⎠

R

⎛⎞

1

-------

× IN-2R

+

⎜⎟

R

⎝⎠

2

2

1

IN+2R

⎛⎞

2

××+× 4KTR14KTR

⎜⎟

3

⎝⎠

2

R

1

-------

1

+

R

2

2

2

R

⎛⎞

1

-------

××××+××× 4KTR31

⎜⎟

R

⎝⎠

2

⎛⎞

××××++ +

⎜⎟
⎝⎠

2

R

1

-------

+

R

2

(EQ. 2)

15

FN7046.4

May 2, 2007

EL2126

Output Drive Capability

The EL2126 is designed to drive low impedance load. It can
easily drive 6V
drive capability makes the EL2126 an ideal choice for RF , IF,
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.

signal into a 100Ω load. This high output

P-P

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.

Power Supply Bypassing And Printed Circuit
Board Layout

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,
where pin 4 (V

4.7µF tantalum capacitor in parallel with a 0.1µF ceramic
capacitor across pins 7 (V

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.

-) is connected to the ground plane, a single

S

+) and pin 4 (VS-) will suffice.

S

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.

As the power supply voltage de creases 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.

16

FN7046.4

May 2, 2007

Small Outline Package Family (SO)

A

D

NN

(N/2)+1

EL2126

h X 45°

PIN #1

E

C

SEATING
PLANE

0.004 C

E1

B

0.010 BM CA

I.D. MARK

1

e

0.010 BM CA

(N/2)

c

SEE DETAIL “X”

L1

H

A2

GAUGE
PLANE

A1

b

DETAIL X

L

4° ±4°

MDP0027

SMALL OUTLINE PACKAGE FAMILY (SO)

INCHES

SO16

SYMBOL

(0.150”)

A 0.068 0.068 0.068 0.104 0.104 0.104 0.104 MAX -
A1 0.006 0.006 0.006 0.007 0.007 0.007 0.007 ±0.003 -
A2 0.057 0.057 0.057 0.092 0.092 0.092 0.092 ±0.002 -

b 0.017 0.017 0.017 0.017 0.017 0.017 0.017 ±0.003 -

c 0.009 0.009 0.009 0.011 0.011 0.011 0.011 ±0.001 -

D 0.193 0.341 0.390 0.406 0.504 0.606 0.704 ±0.004 1, 3

E 0.236 0.236 0.236 0.406 0.406 0.406 0.406 ±0.008 ­E1 0.154 0.154 0.154 0.295 0.295 0.295 0.295 ±0.004 2, 3

e 0.050 0.050 0.050 0.050 0.050 0.050 0.050 Basic -

L 0.025 0.025 0.025 0.030 0.030 0.030 0.030 ±0.009 ­L1 0.041 0.041 0.041 0.056 0.056 0.056 0.056 Basic -

h 0.013 0.013 0.013 0.020 0.020 0.020 0.020 Reference -

N 8 14 16 16 20 24 28 Reference -

NOTES:

1. Plastic or metal protrusions of 0.006” maximum per side are not included.

2. Plastic interlead protrusions of 0.010” maximum per side are not included.

3. Dimensions “D” and “E1” are measured at Datum Plane “H”.

4. Dimensioning and tolerancing per ASME Y14.5M-1994

SO16 (0.300”)

(SOL-16)

SO20

(SOL-20)

SO24

(SOL-24)

SO28

(SOL-28)

TOLERANCE NOTESSO-8 SO-14

A

0.010

Rev. M 2/07

17

FN7046.4

May 2, 2007

EL2126

Small Outline Transistor Plastic Packages (SOT23-5)

D

e1

E

C

L

E1

C

18

FN7046.4

May 2, 2007

SOT-23 Package Family

EL2126

2 3

0.15 DC
2X

C

SEATING
PLANE

E1

5

0.15 A-BC
2X

0.10 C
NX

(L1)

e1

A

6

N

4

D

MDP0038

SOT-23 PACKAGE FAMILY

SYMBOL

MILLIMETERS

TOLERANCESOT23-5 SOT23-6

A 1.45 1.45 MAX

A1 0.10 0.10 ±0.05

E

A2 1.14 1.14 ±0.15

b 0.40 0.40 ±0.05

321

e

0.20

B

b

NX

M

0.20 C
2X

DC A-B

c 0.14 0.14 ±0.06
D 2.90 2.90 Basic
E 2.80 2.80 Basic

E1 1.60 1.60 Basic

e 0.95 0.95 Basic

e1 1.90 1.90 Basic

L 0.45 0.45 ±0.10

L1 0.60 0.60 Reference

1 3

D

N 5 6 Reference

Rev. F 2/07

NOTES:

A2

1. Plastic or metal protrusions of 0.25mm maximum per side are not
included.

2. Plastic interlead protrusions of 0.25mm maximum per side are not

A1

included.

3. This dimension is measured at Datum Plane “H”.

4. Dimensioning and tolerancing per ASME Y14.5M-1994.

5. Index area - Pin #1 I.D. will be located within the indicated zone
(SOT23-6 only).

H

6. SOT23-5 version has no center lead (shown as a dashed line).

A

c

L

0°

GAUGE
PLANE

+3°

-0°

0.25

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19

FN7046.4

May 2, 2007