EL2120C - Elantec Semiconductor

EL2120C January 1996 Rev E

EL2120C

100 MHz Current Feedback Amplifier

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.

Features

#Excellent differential gain and

phase on g5V to g15V supplies

#100 MHz b3 dB bandwidth from

gains of g1tog

#700 V/ms slew rate

#0.1 dB flatness to 20 MHz

#Output disable in 50 ns - remains

high impedance even when

driven with large slew rates

#Single a5V supply operation

#AC characteristics are lot and

temperature stable

#Available in small SO-8 package

Applications

#Video gain block

#Residue amplifier

#Multiplexer

#Current to voltage converter

#Coax cable driver with gain of 2

#ADC driver

Ordering Information

Part No. Temp. Range Package Outline Ý

EL2120CN 0§Ctoa

75§C 8-Pin P-DIP MDP0031

EL2120CS 0§Ctoa

75§C 8-Lead SO MDP0027

Connection Diagrams

P-DIP

2120– 1

2120– 2

Top View

General Description

The EL2120C is a wideband current feedback amplifier opti-

mized for video performance. Its 0.01% differential gain and

0.03 degree differential phase performance when at g5V sup-

plies exceeds the performance of other amplifiers running on

g15V supplies. Operating on g8tog

15V supplies reduces dis-

tortions to 0.01% and 0.01 degrees and below. The EL2120C can

operate with supplies as low as g2.5V or a single a5V supply.

Being a current feedback design, bandwidth is a relatively con-

stant 100 MHz over the g1tog

10 gain range. The EL2120C

has been optimized for flat gain over frequency and all charac-

teristics are maintained at positive unity gain. Because the in-

put slew rate is similar to the 700 V/ms output slew rate the

part makes an excellent high-speed buffer.

The EL2120C has a superior output disable function. Time to

enable or disable is 50 ns and does not change markedly with

temperature. Furthermore, in disable mode the output does not

draw excessive currents when driven with 1000 V/ms slew rates.

The output appears asa3pFload when disabled.

Simplified Schematic

2120– 21

EL2120C

100 MHz Current Feedback Amplifier

Absolute Maximum Ratings

(TAe25§C)

Voltage between Vaand Vb33V

Voltage at aIN,

bIN, VOUT (Vb)b0.5V to (Va)a0.5V

Voltage between

aIN and bIN g5V

Voltage at /Disable (Va)b10V to (Va)a0.5V

Current into aIN,

bIN, and /Disable g5mA

Output Current g50 mA

Internal Power Dissipation See Curves

Operating Ambient

Temperature Range 0§to 75§C

Operating Junction Temperature

P-DIP or SO 150§C

Storage Temperature Range b65§Ctoa

150§C

Important Note:

All parameters having Min/Max specifications are guaranteed. The Test Level column indicates the specific device testing actually

performed during production and Quality inspection. Elantec performs most electrical tests using modern high-speed automatic test

equipment, specifically the LTX77 Series system. Unless otherwise noted, all tests are pulsed tests, therefore T

Test Level Test Procedure

I100% production tested and QA sample tested per QA test plan QCX0002.

II 100% production tested at T

C and QA sample tested at T

MAX

and T

MIN

per QA test plan QCX0002.

III QA sample tested per QA test plan QCX0002.

IV Parameter is guaranteed (but not tested) by Design and Characterization Data.

VParameter is typical value at T

C for information purposes only.

Open Loop DC Electrical Characteristics

VSeg5V; RLe150X,T

Ae25§C unless otherwise specified

Parameter Description Temp Min Typ Max Test Units

Level

VOS Input Offset Voltage Full 4 20 II mV

VSeg15V Full 2 25 II mV

DVOS/DT Input Offset Drift Full 20 V mV/§C

IBaaVIN Input Bias Current Full 5 15 II mA

IBbbVIN Input Bias Current Full 10 50 II mA

CMRR Common-Mode Rejection Full 50 55 II dB

(Note 1)

bICMR bInput Current Common-Mode Full 8 20 II mA/V

Rejection (Note 1)

PSRR Power Supply Rejection Full 65 80 II dB

(Note 2)

aIPSR aInput Current Power Supply 25§C 0.03 V mA/V

Rejection (Note 2)

bIPSR bInput Current Power Supply Full 0.6 5 II mA/V

Rejection (Note 2)

ROL Transimpedance Full 70 140 II kX

AVOL Voltage Gain Full 58 66 II dB

aRIN aVIN Input Impedance 25§C2 VMX

TDis3.2in

EL2120C

100 MHz Current Feedback Amplifier

Open Loop DC Electrical Characteristics

Ð Contd.

VSeg5V; RLe150X,T

Ae25§C unless otherwise specified

Parameter Description Temp Min Typ Max Test Units

Level

VIN aVIN Range Full g3.0 g3.5 II V

VOOutput Voltage Swing Full g3.0 g3.5 II V

ISC Output Short-Circuit 25§C 100 II mA

Current

IO,DIS Output Current, Disabled Full 5 50 II mA

VDIS,ON Disable Pin Voltage for Full (Va)b1IIV

Output Enabled

VDIS,OFF Disable Pin Voltage for Full (Va)b4II V

Output Disabled

IDIS,ON Disable Pin Current for Full 5 II mA

Output Enabled

IDIS,OFF Disable Pin Current for Full 1.0 II mA

Output Disabled

ISSupply Current (VSeg15V) Full 17 20 II mA

Note 1: The input is moved from b3V to a3V.

Note 2: The supplies are moved from g5V to g15V.

Closed Loop AC Electrical Characteristics

VSeg15V; AVea

2(R

FeR

Ge270X); RLe150X;C

Le7 pF; CINbe2 pF; TAe25§C

Parameter Description Min Typ Max Test Units

Level

SR Slew Rate; VOUT from b3V to a3V

Measured at b2V and a2V

VSeg15V 750 V V/ms

VSeg5V 550 V V/ms

tSSettling Time to 0.25% of a

0toa

10V Swing; AVea

1 with

RFe270X,R

Ge%

, and RLe400X50 V ns

BW Bandwidth b3 dB 95 V MHz

g1 dB 50 V MHz

g0.1 dB 16 V MHz

BW@2.5V Bandwidth at b3 dB 75 V MHz

VSeg2.5V g1 dB 35 V MHz

g0.1 dB 11 V MHz

Peaking 0.5 V dB

TDis2.7inTDis2.4in

EL2120C

100 MHz Current Feedback Amplifier

Closed Loop AC Electrical Characteristics

Ð Contd.

VSeg15V; AVea

2(R

FeR

Ge270X); RLe150X;C

Le7 pF; CINbe2 pF; TAe25§C

Parameter Description Min Typ Max Test Units

Level

dG Differential Gain; DC Offset

from b0.7V through a0.7V, AC

Amplitude 286 mVp– p

VSeg15V, f e3.58 MHz k0.01 V %

VSeg15V, f e30 MHz 0.1 V %

VSeg5V, f e3.58 MHz 0.01 V %

diDifferential Phase; DC Offset

from b0.7V through a0.7V, AC

Amplitude 286 mVp– p

VSeg15V, f e3.58 MHz 0.01 V §

VSeg15V, f e30 MHz 0.1 V §

VSeg5V, f e3.58 MHz 0.06 V §

Typical Performance Curves

AC Test Circuit

2120– 3

Frequency Response vs RF

2120– 4

Frequency Response vs Gain

2120– 5

Frequency Response vs Load

2120– 6

TDis2.0in

EL2120C

100 MHz Current Feedback Amplifier

Typical Performance Curves

Ð Contd.

Gain Flatness vs RFGain Flatness vs CINb

at VSg15V

and Peaking vs Temperature

b3 dB Bandwidth, 0.1 dB Bandwidth,

at VSg5V

and Peaking vs Temperature

b3 dB Bandwidth, 0.1 dB Bandwidth,

Peaking vs Supply Voltage

0.1 dB Bandwidth, and

b3 dB Bandwidth,

Phase vs Frequency

Deviation From Linear

2120– 7

EL2120C

100 MHz Current Feedback Amplifier

Typical Performance Curves

Ð Contd.

at 3.58 MHz

DC Input Offset

Differential Gain vs

at 3.58 MHz

DC Input Offset

Differential Phase vs

at 30 MHz

DC Input Offset

Differential Gain vs

at 30 MHz

DC Input Offset

Differential Phase vs

(VIN,DCfrom0toa

0.7V)

vs Supply Voltage

Differential Gain and Phase

and Current

Input Noise Voltage

2120– 8

EL2120C

100 MHz Current Feedback Amplifier

Typical Performance Curves

Ð Contd.

Swing vs Frequency

Undistorted Output

Slew Rate vs Temperature

2120– 9

Small-Signal Transient Response

2120– 10

AVea

2, RFeRGe270X,

RLe150X

Large-Signal Transient Response

2120– 11

AVea

2, RFeRGe270X,

RLe150X,V

Seg

15V

Settling Time vs Swing Long Term Settling Error

2120– 12

EL2120C

100 MHz Current Feedback Amplifier

Typical Performance Curves

Ð Contd.

Enable Response for

a Family of Inputs

2120– 13

AVea

2, RLe150X,

VSeg5V

Disable Response for

a Family of Inputs

AVea

2, RLe150X,2120 – 14

VSeg5V

Supply Voltage

Supply Current vs Maximum Power Dissipation

8-Pin Plastic DIP

vs Ambient Temperature

8-Lead SO

vs Ambient Temperature

Maximum Power Dissipation

2120– 15

EL2120C

100 MHz Current Feedback Amplifier

Applications Information

The EL2120C represents the third generation of

current-feedback amplifier design. It is designed

to provide good high-frequency performance over

wide supply voltage, load impedance, gain, tem-

perature, and manufacturing lot variations. It is

a well-behaved amplifier in spite of its 100 MHz

bandwidth, but a few precautions should be tak-

en to obtain maximum performance.

The power supply pins must be well bypassed.

0.01 mF ceramic capacitors are adequate, but lead

length should be kept below (/4×and a ground

plane is recommended. Bypassing with 4.7 mF

tantalum capacitors can improve settling charac-

teristics, and smaller capacitors in parallel will

not be needed. The lead length of sockets general-

ly deteriorates the amplifier’s frequency response

by exaggerating peaking and increasing ringing

in response to transients. Short sockets cause lit-

tle degradation.

Load capacitance also increases ringing and

peaking. Capacitance greater than 35 pF should

be isolated with a series resistor. Capacitance at

the VINbterminal has a similar effect, and

should be kept below 5 pF. Often, the inductance

of the leads of a load capacitance will be self-reso-

nant at frequencies from 40 MHz to 200 MHz

and can cause oscillations. A resonant load can be

de-Q’ed with a small series or parallel resistor. A

‘‘snubber’’ can sometimes be used to reduce reso-

nances. This is a resistor and capacitor in series

connected from output to ground. Values of 68X

and 33 pF are typical. Increasing the feedback

resistor can also improve frequency flatness.

The VINapin can oscillate in the 200 MHz to

500 MHz realm if presented with a resonant or

inductive source impedance. A series 27Xto 68X

resistor right on the VINapin will suppress such

oscillations without affecting frequency response.

b3 dB bandwidth is inversely proportional to

the value of feedback resistor RF. The EL2120C

will tolerate values as low as 180Xfor a maxi-

mum bandwidth of about 140 MHz, but peaking

will increase and tolerance to stray capacitance

will reduce. At gains greater than 5, b3 dB band-

width begins to reduce, and a smaller RFcan be

used to maximize frequency response.

The greatest frequency response flatness (to

0.1 dB, for instance) occurs with RFe300Xto

330X. Even the moderate peaking caused by low-

er values of RFwill cause the gain to peak out of

the 0.1 dB window, and higher values of RFwill

cause an overcompensated response where the

gain falls below the 0.1 dB level. Parasitic capaci-

tances will generally degrade the frequency flat-

ness.

The EL2120C should not output a continuous

current above 50 mA, as stated in the ABSO-

LUTE MAXIMUM RATINGS table. The out-

put current limit is set to 120 mA at a die temper-

ature of 25§C and reduces to 85 mA at a die tem-

perature of 150§C. This large current is needed to

slew load capacitance and drive low impedance

loads with low distortion but cannot be support-

ed continuously. Furthermore, package dissipa-

tion capabilities cannot be met under short-cir-

cuit conditions. Current limit should not occur

longer than a few seconds.

The output disable function of the EL2120C is

optimized for video performance. While in dis-

able mode, the feedthrough of the circuit can be

modeled as a 0.2 pF capacitor from VINato the

output. No more than g5V can be placed be-

tween VINaand VINbin disable mode, but this

is compatible with common video signal levels.

In disabled state the output can withstand about

1000 V/ms slew rate signals impressed on it with-

out the output transistors turning on.

The /Disable pin logic level is referred to Va.

With g5V supplies, a CMOS or TTL driver with

pull-up resistor will suffice. g15V supplies re-

quire a a14/a11V drive span, or a15/a10V

nominally. Open-collector TTL with a tapped

pull-up resistor can provide these spans. The im-

pedance of the divider should be 1k or less for

optimum enable/disable speed.

The EL2120C enables in 50 ns or less. When VIN

e0, only a small switching glitch occurs at the

output. When VIN is some other value, the out-

put overshoots by about 0.7V when settling

toward its new enabled value.

EL2120C

100 MHz Current Feedback Amplifier

Applications Information

Ð Contd.

When the EL2120C disables, it turns off very rapidly for inputs of g1V or less, and the output sags

more slowly for inputs larger than this. For inputs as large as g2.5V the output current can be

absorbed by another EL2120C simultaneously enabled. Under these conditions, switching will be prop-

erly completed in 50 ns or less.

The greater thermal resistance of the SO-8 package requires that the EL2120C be operated from g10V

supplies or less to maintain the 150§C maximum die temperature over the commercial temperature

range. The P-DIP package allows the full g16.5V supply operation.

Typical Applications CircuitÐA High Quality Two-Input Multiplexer

Dual EL2120C Multiplexer

2120– 16

Channel-to-Channel Isolation

of Dual EL2120C Multiplexer

2120– 17

Dual EL2120C Multiplexer Switching

Channels: Uncorrelated Sinewave

Switched to a Family of DC Levels

2120– 18

Dual EL2120C Multiplexer Switching

Channels: a Family of DC Levels

Switched to an Uncorrelated Sinewave

2120– 19

EL2120C

100 MHz Current Feedback Amplifier

The EL2120C Macromodel

This macromodel has been developed to assist the user in simulating the EL2120C with surrounding

circuitry. It was developed for the PSPICE simulator (copywritten by the Microsim corporation), and

may need to be rearranged for other simulators, particularly the H operator. It approximates frequency

response and small-signal transients as well, although the effects of load capacitance does not show.

This model is slightly more complicated than the models used for low-frequency op-amps, but is much

more accurate for AC.

The model does not simulate these characteristics accurately:

noise non-linearities

slew rate limitations temperature effects

settling time manufacturing variations

input or output resonances CMRR and PSRR

*Revision A. March 1992

*Enhancements include PSRR, CMRR, and Slew Rate Limiting

*Connections: ainput

binput

Vsupply

lll

Vsupply

llll

output

lllll

.subckt M2120 3 2746

*Input Stage *

*q141819qp

e1100301.0 q271820qn

vis1090V q371921qn

h2912vxx1.0 q442022qp

r121125 r72164

l1 11 12 20nH r8 22 6 4

iinp3010mA ios1 7 19 2.5mA

iinm205mA ios2 20 4 2.5mA

r12 3 0 2Meg *

**Supply

*Slew Rate Limiting *

*ips 7 4 10mA

h1 13 0 vis 600 *

r2 13 14 1K *Error Terms

d1 14 0 dclamp *

s2 0 14 dclamp ivos 0 23 5mA

*vxx 23 0 0V

*High Frequency Pole e4 240601.0

*e5250701.0

e2 30 0 14 0 0.00166666666 e6 260401.0

15 30 17 1mH r92423562

c5 17 0 0.5pF r10 25 23 10K

r5 17 0 600 r11 26 23 10K

*Transimpedance Stage *Models

g1 0 18 17 0 1.0 .model qn npn (ise5eb15 bfe500 tfe0.1nS)

rol 18 0 140K .model qp pnp (ise5eb15 bfe500 tfe0.1nS)

cdp 18 0 7.9pF .model dclamp d(ise1eb30 ibve0.02 bve4ne

*.ends

*Output Stage

TABWIDE

TDis3.8in TD

EL2120CJanuary 1996 Rev E

EL2120C

100 MHz Current Feedback Amplifier

The EL2120C Macromodel

Ð Contd.

2120– 20

EL2120 Macromodel

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 circuitry 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.

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1996 Tarob Court

Milpitas, CA 95035

Telephone: (408) 945-1323

(800) 333-6314

Fax: (408) 945-9305

European Office: 44-71-482-4596

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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 in-

tended to support or sustain life and whose failure to perform

when properly used in accordance with instructions provided can

be reasonably expected to result in significant personal injury or

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in Life Support Systems are requested to contact Elantec, Inc.

factory headquarters to establish suitable terms & conditions for

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ment of defective components and does not cover injury to per-

sons or property or other consequential damages.

Printed in U.S.A.12