EL2125CW-T7 - Intersil Corporation

FN7045.3

EL2125

Ultra-Low Noise, Low Power, Wideband

Amplifier

The EL2125 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 EL2125 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 SOIC

packages.

The EL2125 is fabricated using Elantec’s proprietary

complementary bipolar process, and is specified for

operation from -45°C to +85°C.

Features

• Voltage noise of only 0.83nV/√Hz

• Current noise of only 2.4pA/√Hz

• 200µV offset voltage

• 175MHz -3dB BW for AV = 10

• Low supply current - 10mA

• SOT-23 package available

• ±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

Pinouts

EL2125

(5 LD SOT-23)

TOP VIEW

EL2125

(8 LD SOIC)

TOP VIEW

Ordering Information

PART NUMBER PART

MARKING TAPE &

REEL PACKAGE PKG.

DWG. #

EL2125CW-T7 F 7”

(3k pcs) 5 Ld SOT-23 MDP0038

EL2125CW-T7A F 7”

(250 pcs) 5 Ld SOT-23 MDP0038

EL2125CS 2125CS - 8 Ld SOIC MDP0027

EL2125CS-T7 2125CS 7” 8 Ld SOIC MDP0027

EL2125CS-T13 2125CS 13” 8 Ld SOIC MDP0027

EL2125CSZ

(See Note) 2125CSZ - 8 Ld SOIC

(Pb-free) MDP0027

EL2125CSZ-T7

(See Note) 2125CSZ 7” 8 Ld SOIC

(Pb-free) MDP0027

EL2125CSZ-T13

(See Note) 2125CSZ 13” 8 Ld SOIC

(Pb-free) MDP0027

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.

OUT

VS-

IN+

VS+

IN-

OUT

VS-

IN+

VS+IN- -

Data Sheet May 4, 2007

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.

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

2FN7045.3

May 4, 2007

Absolute Maximum Ratings (TA = +25°C) Thermal Information

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

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

Any Input . . . . . . . . . . . . . . . . . . . . . . . . . . VS- - 0.3V to VS+ + 0.3V

Ambient Operating Temperature . . . . . . . . . . . . . . . .-45°C to +85°C

Storage Temperature. . . . . . . . . . . . . . . . . . . . . . . -65°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

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 = TA

Electrical Specifications VS = ±5V, TA = +25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified.

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNIT

DC PERFORMANCE

VOS Input Offset Voltage (SO8) 0.2 2 mV

Input Offset Voltage (SOT23-5) 3mV

TCVOS Offset Voltage Temperature Coefficient 1.8 µV/°C

IBInput Bias Current -30 -22 µA

IOS Input Bias Current Offset 0.4 2 µA

TCIB Input Bias Current Temperature

Coefficient 0.09 µA/°C

CIN Input Capacitance 2.2 pF

AVOL Open Loop Gain 80 87 dB

PSRR Power Supply Rejection Ratio

(Note 1) 80 97 dB

CMRR Common Mode Rejection Ratio at CMIR 80 106 dB

CMIR Common Mode Input Range -4.6 3.8 V

VOUTH Output Voltage Swing High No load, RF = 1kΩ3.5 3.65 V

VOUTL Output Voltage Swing Low No load, RF = 1kΩ-3.87 -3.7 V

VOUTH2 Output Voltage Swing High RL = 100Ω33.3 V

VOUTL2 Output Voltage Swing Low RL = 100Ω-3.5 -3 V

IOUT Output Short Circuit Current (Note 2) 80 100 mA

ISSupply Current 10.1 11 mA

AC PERFORMANCE - RG = 20Ω, CL = 5pF

BW -3dB Bandwidth 175 MHz

BW ±0.1dB ±0.1dB Bandwidth 34 MHz

BW ±1dB ±1dB Bandwidth 150 MHz

Peaking Peaking 0.4 dB

SR Slew Rate VOUT = 2VP-P, measured at 20% to 80% 150 185 V/µs

OS Overshoot, 4VP-P Output Square Wave Positive 0.6 %

Negative 2.7 %

tSSettling Time to 0.1% of ±1V Pulse 42 ns

EL2125

3FN7045.3

May 4, 2007

VNVoltage Noise Spectral Density 10kHz 0.83 nV/√Hz

INCurrent Noise Spectral Density 10kHz 2.4 pA/√Hz

HD2 2nd Harmonic Distortion (Note 3) -74 dBc

HD3 3rd Harmonic Distortion -91 dBc

NOTES:

1. Measured by moving the supplies from ±4V to ±6V

2. Pulse test only

3. Frequency = 1MHz, VOUT = 2VP-P, into 500Ω and 5pF load

Electrical Specifications VS = ±5V, TA = +25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified. (Continued)

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNIT

Electrical Specifications VS = ±15V, TA = +25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified.

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNIT

DC PERFORMANCE

VOS Input Offset Voltage (SO8) 0.6 3 mV

Input Offset Voltage (SOT23-5) 3mV

TCVOS Offset Voltage Temperature Coefficient 4.9 µV/°C

IBInput Bias Current -30 -24 µA

IOS Input Bias Current Offset 0.4 2 µA

TCIB Input Bias Current Temperature

Coefficient 0.08 µA/°C

CIN Input Capacitance 2.2 pF

AVOL Open Loop Gain 80 87 dB

PSRR Power Supply Rejection Ratio

(Note 4) 80 97 dB

CMRR Common Mode Rejection Ratio at CMIR 75 105 dB

CMIR Common Mode Input Range -14.6 13.8 V

VOUTH Output Voltage Swing High No load, RF = 1kΩ13.35 13.5 V

VOUTL Output Voltage Swing Low No load, RF = 1kΩ-13.6 -13 V

VOUTH2 Output Voltage Swing High RL = 100Ω11 11.6 V

VOUTL2 Output Voltage Swing Low RL = 100Ω-10.4 -9.8 V

IOUT Output Short Circuit Current (Note 5) 120 250 mA

ISSupply Current 10.8 12 mA

AC PERFORMANCE - RG = 20Ω, CL = 5pF

BW -3dB Bandwidth 220 MHz

BW ±0.1dB ±0.1dB Bandwidth 23 MHz

BW ±1dB ±1dB Bandwidth 63 MHz

Peaking Peaking 2.5 dB

SR Slew Rate VOUT = 2VP-P, measured at 20% to 80% 180 225 V/µs

OS Overshoot, 4VP-P Output Square Wave 0.6 %

tSSettling Time to 0.1% of ±1V Pulse 38 ns

EL2125

4FN7045.3

May 4, 2007

VNVoltage Noise Spectral Density 10kHz 0.95 nV/√Hz

INCurrent Noise Spectral Density 10kHz 2.1 pA/√Hz

HD2 2nd Harmonic Distortion (Note 6) -73 dBc

HD3 3rd Harmonic Distortion -96 dBc

NOTES:

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

5. Pulse test only

6. Frequency = 1MHz, VOUT = 2VP-P, into 500Ω and 5pF load

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

PARAMETER DESCRIPTION CONDITIONS MIN TYP MAX UNIT

Typical Performance Curves

FIGURE 1. NON-INVERTING FREQUENCY RESPONSE FO R

VARIOUS RFFIGURE 2. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

FIGURE 3. INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

FIGURE 4. INVERTING FREQUENCY RESPONSE FOR

VARIOUS RF

-5

1M 10M 100M

FREQUENCY (Hz)

NORMALIZED GAIN (dB)

VS = ±5V

AV = 10

RL = 500Ω

CL = 5pF

200M

RF = 1kΩRF = 499Ω

RF = 180Ω

RF = 100Ω

-5

1M 10M 100M

FREQUENCY (Hz)

NORMALIZED GAIN (dB)

VS = ±15V

AV = 10

RL = 500Ω

CL = 5pF

300M

RF = 1kΩ

RF = 180Ω

RF = 700Ω

RF = 100Ω

RF = 499 Ω

-2

-6

-10

-14

1M 10M 100M 300M

FREQUENCY (Hz)

NORMALIZED GAIN (dB)

VS = ±5V

AV = -10

RL = 560Ω

CL = 5pF

RF = 1kΩ

RF = 350Ω

RF = 200Ω

RF = 97.6Ω

RF = 499Ω

-2

-6

-10

-14

1M 10M 100M 300M

FREQUENCY (Hz)

NORMALIZED GAIN (dB)

VS = ±15V

AV = -10

RL = 500Ω

CL = 5pF

RF = 1kΩ

RF = 350Ω

RF = 200 Ω

RF = 499Ω

RF = 97.6Ω

EL2125

5FN7045.3

May 4, 2007

FIGURE 5. NON-INVERTING FREQUENCY RESPONSE vs GAIN FIGURE 6. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS GAIN

FIGURE 7. INVERTING FREQUENCY RESPONSE vs GAIN FIGURE 8. INVERTING FREQUENCY RESPONSE vs GAIN

FIGURE 9. NON-INVERTING FREQUENCY RESPONSE FO R

VARIOUS OUTPUT SIGNAL LEVELS FIGURE 10. INVERTING FREQUENCY RESPONS E FOR

VARIOUS OUTPUT SIGNAL LEVELS

Typical Performance Curves (Continued)

-5

1M 10M 100M 200M

FREQUENCY (Hz)

NORMALIZED GAIN (dB)

VS = ±5V

RL = 500Ω

CL = 5pF

RG = 20Ω

AV = 50 AV = 20

AV = 10

-5

NORMALIZED GAIN (dB)

VS = ±15V

RL = 500Ω

CL = 5pF

RF = 700Ω

1M 10M 100M 200M

FREQUENCY (Hz)

AV = 50

AV = 20

AV = 10

NORMALIZED GAIN (dB)

-2

-6

-10

1M 10M 100M 300M

FREQUENCY (Hz)

-14

AV = -10

AV = -50

VS = ±5V

RL = 500Ω

CL = 5pF

RG = 35Ω

AV = -20

-14

NORMALIZED GAIN (dB)

1M 10M 100M 300M

FREQUENCY (Hz)

AV = -50 AV = -20

AV = -10

VS = ±15V

RL = 500Ω

CL = 5pF

RG = 50Ω

-5

NORMALIZED GAIN (dB)

1M 10M 100M 200M

FREQUENCY (Hz)

VS = ±5V

AV = 10

RF = 180Ω

RL = 500Ω

CL = 5pF

2VPP

4VPP

30mVPP

500mVPP

1VPP

-14

NORMALIZED GAIN (dB)

1M 10M 100M 300M

FREQUENCY (Hz)

VS = ±5V

AV = -10

RF = 350Ω

RL = 500Ω

CL = 5pF

2.5VPP

500mVPP

3.3VPP

250mVPP

3mVPP

1VPP

EL2125

6FN7045.3

May 4, 2007

FIGURE 1 1. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

FIGURE 12. NON-INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

FIGURE 13. INVERTING FREQUENCY RESPONSE FOR

VARIOUS CLFIGURE 14. INVERTING FREQUENCY RESPONSE FOR

VARIOUS CL

FIGURE 15. OPEN LOOP GAIN AND PHASE FIGURE 16. SUPPLY CURRENT vs SUPPLY VOLTAGE

Typical Performance Curves (Continued)

NORMALIZED GAIN (dB)

-1

-3

-5

1M 10M 100M 200M

FREQUENCY (Hz)

VS = ±5V

AV = 10

RF = 180Ω

RL = 500Ω

CL = 28.5pF

CL = 16pF

CL = 5pF

CL = 1pF

NORMALIZED GAIN (dB)

-5

1M 10M 100M 200M

FREQUENCY (Hz)

VS = ±5V

AV = 10

RF = 700Ω

RL = 500Ω

CL = 17pF

CL = 11pF

CL = 1.2pF

CL = 5pF

NORMALIZED GAIN (dB)

1M 10M 100M 300M

FREQUENCY (Hz)

-14

VS = ±5V

AV = 10

RF = 350Ω

RL = 500Ω

CL = 29.4pF

CL = 16.4pF

CL = 5.1pF

CL = 1.2pF

CL = 11.4pF

NORMALIZED GAIN (dB)

-2

-6

-10

-14

1M 10M 100M 300M

FREQUENCY (Hz)

VS = ±15V

AV = 10

RF = 500Ω

RL = 500Ω

CL = 29.4pF

CL = 16.4pF

CL = 11.4pF

CL = 5.1pF

CL = 1.2pF

OPEN LOOP GAIN (dB)

10K 10M

100

100K 100M

FREQUENCY (Hz)

PHASE (°)

-250

-50

-150

150

250

400M

GAIN PHASE

VS = ±5V 00

SUPPLY VOLTAGE (±V)

SUPPLY CURRENT (mA)

4.8

2.4

31215

9.6

7.2

EL2125

7FN7045.3

May 4, 2007

FIGURE 17. 3dB BANDWIDTH vs SUPPLY VOLTAGE FIGURE 18. PEAKING vs SUPPLY VOLTAGE

FIGURE 19. SMALL SIGNAL STEP RESPONSE FIGURE 20. SMALL SIGNAL STEP RESPONSE

FIGURE 21. LARGE SIGNAL STEP RESPONSE FIGURE 22. LARGE SIGNAL STEP RESPONSE

Typical Performance Curves (Continued)

250

200

150

100

0246810121416

VS (±V)

BANDWIDTH (MHz)

AV = 10

AV = -10

AV = 50 AV = -50AV = 20AV = -20

2.5

1.5

0.5

02 4 6 8 10 12 14 16

VS (±V)

PEAKING (dB)

AV = 10

AV = -10

AV = 50

AV = -50AV = 20

AV = -20

10ns/DIV

20mV/DIV

VINx2

VS = ±5V

RL = 500Ω

RF = 180Ω

AV = 10

CL = 5pF

10ns/DIV

20mV/DIV

VINx2

VS = ±15V

RL = 500Ω

RF = 180Ω

AV = 10

CL = 5pF

TIME (20ns/DIV)

OUTPUT VOLTAGE (0.5V/DIV)

VS = ±5V

RL = 500Ω

RF = 180Ω

AV = 10

CL = 5pF

TIME (20ns/DIV)

OUTPUT VOLTAGE (0.5V/DIV)

VS = ±15V

RL = 500Ω

RF = 180Ω

AV = 10

CL = 5pF

EL2125

8FN7045.3

May 4, 2007

FIGURE 23. 1MHz HARMONIC DISTORTION vs OUTPUT

SWING FIGURE 24. 1MHz HARMONIC DISTORTION vs OUTPUT

SWING

FIGURE 25. TOTAL HARMONIC DISTORTION vs FREQUENCY FIGURE 26. VOLTAGE AND CURRENT NOISE vs FREQUENCY

FIGURE 27. SETTLING TIME vs ACCURACY FIGURE 28. GROUP DELAY

Typical Performance Curves (Continued)

-40

-50

-60

-70

-90

-100

-110067

VOUT (VPP)

DISTORTION (dBc)

45231

-80

VS = ±5V

RF = 180Ω

AV = 10

RL = 500Ω

2ND HD

3RD HD

-30

-40

-60

-80

-90

-100

-11005 25

VOUT (VPP)

DISTORTION (dBc)

VS = ±15V

RF = 180Ω

AV = 10

RL = 500Ω

10 15 20

-50

-70

2ND HD

3RD HD

-30

-60

-80

-90

1K 10K 100M

FREQUENCY (Hz)

THD (dBc)

VS = ±5V

VO = 2VPP

AV = 10

RF = 180Ω

RL = 500Ω

100K 1M 10M

-40

-50

-70

100

0.1

10 100 1K 10K 100K

FREQUENCY (Hz)

VOLTAGE NOISE (nV/√Hz),

CURRENT NOISE (pA/√Hz)

IN, VS = ±5V

IN, VS = ±15V

VN, VS = ±5V

VN, VS = ±15V

0.1 1 10

ACCURACY (%)

SETTLING TIME (ns)

VS = ±15V

VO = 5VPP

VS = ±5V

VO = 5VPP

VS = ±15V

VO = 2VPP

VS = ±5V

VO = 2VPP

-6

1 400

FREQUENCY (MHz)

GROUP DELAY (ns)

-2

10 100

AV = 20

AV = 10

VS = ±15V

EL2125

9FN7045.3

May 4, 2007

FIGURE 29. CMRR FIGURE 30. PSRR

FIGURE 31. CLOSED LOOP OUTPUT IMPEDANCE vs

FREQUENCY FIGURE 32. BANDWIDTH vs TEMPERATURE

FIGURE 33. SLEW RATE vs SWING FIGURE 34. SUPPLY CURRENT vs TEMPERATURE

Typical Performance Curves (Continued)

-110

-10

10 100M

FREQUENCY (Hz)

CMRR (dB)

-70

-30

-50

-99

100 10M

1k 10k 100k 1M

PSRR (dB)

10k 10M

110

100k 100M

FREQUENCY (Hz)

PSRR-

PSRR+

600M

ROUT (Ω)

0.001

0.1

0.01

10K

100

FREQUENCY (Hz)

100M

100K 1M 10M

200

160

-40 160

TEMPERATURE (°C)

-3dB BANDWIDTH (MHz)

120

800 40 120

3.5

2.5

1.5

0.5

PEAKING (dB)

BANDWIDTH

PEAKING

SLEW RATE (V/µs)

100

200

150

250

300

350

VOUT SWING (VPP)

2051015

5VSR-

15VSR+

15VSR-

5VSR+

-50 0 100 15050

DIE TEMPERATURE (°C)

IS (mA)

VS = ±5V

VS = ±15V

EL2125

10 FN7045.3

May 4, 2007

FIGURE 35. OFFSET VOLTAGE vs TEMPERATURE FIGURE 36. INPUT BIAS CURRENT vs TEMPERATURE

FIGURE 37. CMRR vs TEMPERATURE FIGURE 38. PSRR vs TEMPERATURE

FIGURE 39. SLEW RATE vs TEMPERATURE FIGURE 40. POSITIVE OUTPUT SWING vs TEMPERATURE

Typical Performance Curves (Continued)

-1

-2

-3

-50 0 100 15050

DIE TEMPERATURE (°C)

VS = ±5V

VS = ±15V

VOS (mV)

-50 0 100 15050

DIE TEMPERATURE (°C)

IB+ (µA)

-10

-15

-20

-25

-30

120

100

-50 0 100 15050

DIE TEMPERATURE (°C)

CMRR (dB)

VS = ±5V

VS = ±15V

110

100

-50 0 100 15050

DIE TEMPERATURE (°C)

PSRR (dB)

VS = ±5V

VS = ±15V

240

220

200

180

160

-50 0 100 15050

DIE TEMPERATURE (°C)

SR (V/µs)

VS = ±5V

VS = ±15V

VO = 2VPP 3.9

3.7

3.6

3.5

3.8

-50

DIE TEMPERATURE (°C)

VOUTH (V)

0 100 15050

VS = ±5V

EL2125

11 FN7045.3

May 4, 2007

FIGURE 41. POSITIVE OUTPUT SWING vs TEMPERATURE FIG UR E 42. NEGATIVE OUTPUT SWING vs TEMPERATURE

FIGURE 43. NEGATIVE OUTPUT SWING vs TEMPERATURE FIGURE 44. LOADED NEGA TIVE OUTPUT SWING vs

TEMPERATURE

FIGURE 45. NEGATIVE OUTPUT SWING vs TEMPERATURE FIGURE 46. LOADED POSITIVE OUTPUT SWING vs

TEMPEARTURE

Typical Performance Curves (Continued)

13.6

13.5

13.4

-50

DIE TEMPERATURE (°C)

0 100 15050

VOUTH (V)

VS = ±15V

-9.75

-9.8

-9.85

-9.9

-9.95

-50

DIE TEMPERATURE (°C)

VOUTL (V)

0 10050

VS = ±5V

150

-13.4

-13.5

-13.6

-13.7

-50

DIE TEMPERATURE (°C)

VOUTL (V)

0 100 15050

VS = ±15V

-3.42

-3.44

-3.46

-3.48

-3.5

-3.52

-50

DIE TEMPERATURE (°C)

VOUTL2 (V)

0 100 15050

VS = ±5V

-9.6

-9.8

-10

-10.2

-10.4

-10.6

-10.8

-50

DIE TEMPERATURE (°C)

VOUTL2 (V)

010015050

VS = ±15V

3.35

3.3

3.25

-50

DIE TEMPERATURE (°C)

VOUTH2 (V)

010015050

VS = ±5V

EL2125

12 FN7045.3

May 4, 2007

FIGURE 47. LOADED POSITIVE OUTPUT SWING vs

TEMPERATURE FIGURE 48. P ACKAGE POWER DISSIPA TION vs AMBIENT

TEMPERATURE

FIGURE 49. P ACKAGE POWER DISSIPA TION vs AMBIENT

TEMPERATURE

Typical Performance Curves (Continued)

11.8

11.6

11.4

11.2

-50

DIE TEMPERATURE (°C)

VOUTH2 (V)

0 100 15050

VS = ±15V

1.2

0.6

JEDEC JESD51-3 LOW EFFECTIVE THERMAL

CONDUCTIVITY TEST BOARD

AMBIENT TEMPERATURE (°C)

POWER DISSIPATION (W)

25 125 15075

0.4

0.8

0.2

10050 85

488mW

781mW SO8

θJA=160°C/W

SOT23-5

θJA=256°C/W

1.8

0.8

1.6

0.4

1.2

0.2

0.6

1.4

JEDEC JESD51-7 HIGH EFFECTIVE THERMAL

CONDUCTIVITY TEST BOARD

AMBIENT TEMPERATURE (°C)

POWER DISSIPATION (W)

25 125 15075 10050 85

543mW

1.136W SO8

θJA=110°C/W

SOT23-5

θJA=230°C/W

EL2125

13 FN7045.3

May 4, 2007

Applications Information

Product Descr iption

The EL2125 is an ultra-low noise, wideband monolithic

operational amplifier built on Elantec's proprietary high

speed complementary bipolar process. It features

0.83nV/√Hz input voltage noise, 200µV offset voltage, and

73dB THD. It is intended for use in systems such as

ultrasound imaging where very small signals are ne eded to

be amplified. The EL2125 also has excellent DC

specifications: 200µV VOS, 22µA IB, 0.4µA IOS, and 106dB

CMRR. These specifications allow the EL2125 to be used in

DC-sensitive applications such as difference amplifiers.

Gain-Bandwidth Product

The EL2125 has a gain-bandwidth product of 800MHz at

±5V. For gains greater than 20, its closed-loop -3dB

bandwidth is approximately equal to the gain-bandwidth

product divided by the small signal gain of the circuit. For

gains less than 20, higher-order poles in the amplifier's

transfer function contribute to even higher closed-loop

bandwidths. For example, the EL2125 has a -3dB bandwidth

of 175MHz at a gain of 10 and decreases to 40MHz 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 EL2125 is designed for gain > 10 with external

compensation, the device can also operate at lower gain

settings. The RC network shown 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 2πRC must be less than 400MHz.

FIGURE 50.

Choice of Feedback Resistor, RF

The feedback resistor forms a pole with th e 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 the in typical performance curves section

of this data sheet.

Pin Descriptions

5 LD SOT-23 8 LD SO PIN NAME PIN FUNCTION EQUIVALENT CIRCUIT

16VOUTOutput

CIRCUIT 1

2 4 VS- Supply

3 3 VINA+ Input

CIRCUIT 2

4 2 VINA- Input Reference Circuit 2

5 7 VS+ Supply

VOUT

VS+

VIN-VIN+

VS+

VS-

VIN

VOUT

EL2125

14 FN7045.3

May 4, 2007

Noise Calculations

The primary application for the EL2125 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 below shows all the noise sour ces for all the

components around the amplifier .

FIGURE 51.

•V

N is the amplifier input voltage noise

•I

N+ is the amplifier positive input current noise

•I

N- is the amplifier negative input current noise

•V

RX is the thermal noise associated with each resistor:

where:

• k is Boltzmann's constant = 1.380658 x 10-23

• 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 below

(Figure 52).

As the equation shows, to keep noise at a minimum, small

resistor values should be used. At higher amplifier gain

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

and R1 decreases and the noise caused by IN+, VN, and R3

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.

Output Drive Capability

The EL2125 is designed to drive low impedance load. It can

easily drive 6VP-P signal into a 100Ω load. This high output

drive capability makes the EL2125 an ideal choice for RF, IF,

and video applications. Furthermore, the EL2125 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 p ackage.

Driving Cables and Capacitive Loads

Although the EL2125 is designed to drive low impedance

load, capacitive loads will decrease the amplifier's phase

margin. As shown the 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 co axial

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 (VS-) is connected to the ground plane, a single

4.7µF tantalum capacitor in parallel with a 0.1µF ceramic

capacitor acros s pins 7 (VS+) and pin 4 (VS-) will suffice.

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.

Supply Voltage Range and Single Supply

Operation

The EL2125 has been designed to operate with supply

voltage range of ±2.5V to ±15V. With a single supply, the

EL2125 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. Wh en used in dual supply mode, the

negative power supply is connected to pin 4.

As the power supp l y vol tage decreases from +30V to +5V, it

becomes necessary to pay special attention to the input

voltage range. The EL2125 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 EL2125

has an input voltage range which spans from 0.4V to 3.8V.

The output range of the EL2125 is also quite large, on a +5V

supply, it swings from 0.4V to 3.6V.

+VON

VIN

IN+

IN-

VR3

VR2

VR1

VRX 4kTRx=

VON BW=VN21R1

-------+

⎝⎠

⎜⎟

⎛⎞

×IN-2R1

2IN+2R3

21R1

-------+

⎝⎠

⎜⎟

⎛⎞

××+×4KTR

14KTR

-------

⎝⎠

⎜⎟

⎛⎞

××××+××× 4KTR

31R1

-------+

⎝⎠

⎜⎟

⎛⎞

××××++ +

⎝ ⎠

⎜ ⎟

⎛ ⎞

FIGURE 52.

EL2125

15 FN7045.3

May 4, 2007

EL2125

Small Outline Package Family (SO)

GAUGE

PLANE

A1 L

DETAIL X 4° ±4°

SEATING

PLANE

0.010 BMCA

0.004 C

0.010 BMCA

(N/2)

NN (N/2)+1

PIN #1

I.D. MARK

h X 45°

SEE DETAIL “X”

0.010

MDP0027

SMALL OUTLINE PACKAGE FAMILY (SO)

SYMBOL

INCHES

TOLERANCE NOTESSO-8 SO-14

SO16

(0.150”)

SO16 (0.300”)

(SOL-16)

SO20

(SOL-20)

SO24

(SOL-24)

SO28

(SOL-28)

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 -

Rev. M 2/07

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

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

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For information regarding Intersil Corporation and its products, see www.intersil.com

FN7045.3

May 4, 2007

EL2125

SOT-23 Package Family

321

0.15 DC

2X 0.20 C

B0.20 MDC A-B

2 3

SEATING

PLANE

0.10 C

1 3

0.15 A-BC

(L1)

0.25

0° +3°

-0°

GAUGE

PLANE

MDP0038

SOT-23 PACKAGE FAMILY

SYMBOL

MILLIMETERS

TOLERANCESOT23-5 SOT23-6

A 1.45 1.45 MAX

A1 0.10 0.10 ±0.05

A2 1.14 1.14 ±0.15

b 0.40 0.40 ±0.05

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

N 5 6 Reference

Rev. F 2/07

NOTES:

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

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).

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