Datasheet EL400CS, EL400CN Datasheet (ELANT)

EL400C

200MHz Current Feedback Amplifier

EL400C

Features

• 200MHz -3dB bandwidth, AV=2

• 12ns settling to 0.05%

• VS = ±5V @ 15mA

• Low distortion: HD2, HD3 @

-60dBc at 20MHz

• Differential gain 0.02% at NTSC,
PAL

• Differential phase 0.01° at NTSC,
PAL

• Overload/short-circuit protected

• ±1 to ±8 closed-loop gain range

• Low cost

• Direct replacement for CLC400

Applications

• Video gain block

• Video distribution

• HDTV amplifier

• High-speed A/D conversion

• D/A I-V conversion

• Photodiode, CCD preamps

• IF processors

• High-speed communications

General Description

The EL400C is a wide bandwidth, fast settling monolithic amplifier
built using an advanced complementary bipolar process. This ampli­fier uses current-mode feedback to achieve more bandwidth at a given
gain than conventional operational amplifiers. Designed for closed­loop gains of ±1 to ±8, the EL400C has a 200MHz -3dB bandwidth
(AV = +2), and 12ns settling to 0.05% while consuming only 15mA of
supply current.

The EL400C is an obvious high-performance solution for video distri­bution and line-driving applications. With low 15mA supply current,
differential gain/phase of 0.02%/0.01°, and a minimum 50mA output
drive, performance in these areas is assured.

The EL400's settling to 0.05% in 12ns, low distortion, and ability to
drive capacitive loads make it an ideal flash A/D driver. The wide
200MHz bandwidth and extremely linear phase allow unmatched sig­nal fidelity. D/A systems can also benefit from the EL400C, especially
if linearity and drive levels are important.

Ordering Information

Part No. Temp. Range Package Outline #

EL400CN -40°C to +85°C 8-Pin P-DIP MDP0031

EL400CS -40°C to +85°C 8-Lead SO MDP0027

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.

© 2001 Elantec Semiconductor, Inc.

Connection Diagrams

DIP and SO Package

Top View

Manufactured under U.S. Patent No. 4,893,091

September 26, 2001

EL400C

200MHz Current Feedback Amplifier

EL400C

Absolute Maximum Ratings (T

Supply Voltage (VS) ±7V

Output Current

Output is short-circuit protected to ground, however, maximum reliability is obtained if
I

does not exceed 70mA.

OUT

Common-Mode Input Voltage ±V

Differential Input Voltage 5V

Power Dissipation See Curves

= 25°C)

A

Operating Temperature -40°C to +85°C

Lead Temperature (Soldering, 5 Seconds) 300°C

Junction Temperature 175°C

Storage Temperature -60°C to +150°C

S

Thermal Resistance:

θ

= 95°C/W P-DIP

JA

θ

= 175°C/W SO-8

JA

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.

Open Loop DC Electrical Characteristics

VS = ±5V, R

Parameter Description Test Conditions Temp Min Typ Max Unit

V

d(VOS)/dT Average Offset Voltage Drift

+I

d(+IIN)/dT Average +Input Current Drift

-I

d(-IIN)/dT Average -Input Current Drift

PSRR Power Supply Rejection Ratio All 40.0 50.0 dB

CMRR Common-Mode Rejection Ratio All 40.0 50.0 dB

I

S

+R

C

R

CMIR Common-Mode Input Range

I

OUT

V

V

R

= 100Ω unless otherwise specified

L

OS

IN

IN

Input Offset Voltage 25°C 2.0 5.5 mV

[1]

+Input Current 25°C, T

-Input Current 25°C 10.0 25.0 µA

Supply Current—Quiescent No Load All 15.0 23.0 mA

IN

IN

OUT

+Input Resistance 25°C, T

Input Capacitance All 0.5 2.0 pF
Output Impedance (DC) All 0.1 0.2 Ω

[2]

Output Current 25°C, T

OUT

OUTL

OL

1. Measured from T

Output Voltage Swing No Load All 3.2 3.5 V
Output Voltage Swing 100Ω 25°C 3.0 3.4 V

Transimpedance 25°C 30.0 125.0 V/mA

to T

MAX

.

MIN

2. Common-Mode Input Range for Rated Performance.

T

T

MIN

MAX

8.7 mV

9.5 mV

All 10.0 40.0 µV/°C

MAX

T

[1]

[1]

MIN

All 50.0 200.0 nA/°C

T

MIN

T

MAX

All 100.0 200.0 nA/°C

100.0 200.0 kΩ

50.0 kΩ

2.0 2.1 V

1.2 V

50.0 70.0 mA

35.0 mA

T

25°C, T

T

T

T

T

MAX

MAX

MIN

MAX

MIN

MAX

MIN

MIN

10.0 25.0 µA

41.0 µA

41.0 µA

35.0 µA

80.0 V/mA

140.0 V/mA

2

200MHz Current Feedback Amplifier

Closed-Loop AC Electrical Characteristics

VS = ±5V, R

Frequency
Response

Gain Flatness GFPL Peaking

Time-Domain
Response

Distortion HD2 2nd Harmonic Distortion at 20MHz 2V

Equivalent Input
Noise

Video
Performance

1. Noise Tests are Performed from 5MHz to 200MHz.

2. Differential Gain/Phase Tests are R

= 250Ω, A

F

= +2, R

= 100Ω unless otherwise specified

V

L

Parameter Description Test Conditions Temp Min Typ Max Unit

SSBW -3dB Bandwidth

(V

< 0.5VPP)

OUT

LSBW -3dB Bandwidth

(V

< 5.0VPP)

OUT

AV = +5 All 35.0 50.0 MHz

25°C 150.0 200.0 MHz

T

T

MIN

MAX

150.0 MHz

120.0 MHz

<40MHz 25°C 0.0 0.3 dB

V

< 0.5V

OUT

GFPH Peaking

V

OUT

GFR Rolloff

V

OUT

LPD Linear Phase Deviation

V

OUT

tr1, tf1Rise Time, Fall Time 0.5V Step 25°C, T

< 0.5V

< 0.5V

< 0.5V

PP

T

, T

MIN

MAX

>40MHz 25°C 0.0 0.5 dB

PP

T

, T

MIN

MAX

<75MHz 25°C 0.6 1.0 dB

PP

<75MHz 25°C, T

PP

T

T

T

T

MIN

MAX

MAX

MAX

MIN

MIN

0.2 1.0 °

1.6 2.4 ns

tr2, tf2Rise Time, Fall Time 5.0V Step All 6.5 10.0 ns

t

Settling Time to 0.1% 2.0V Step All 10.0 13.0 ns

s1

t

Settling Time to 0.05% 2.0V Step All 12.0 15.0 ns

s2

OS Overshoot 0.5V Step 25°C 0.0 10.0 %

T

, T

MIN

MAX

SR Slew Rate AV = +2 All 430.0 700.0 V/µs

AV = - 2 All 1600.0 V/µs

25°C -60.0 -45.0 dBc

T

MIN

T

MAX

25°C -60.0 -50.0 dBc

T

, T

MIN

MAX

25°C -157.0 -154.0 dBm

HD3 3rd Harmonic Distortion at 20MHz 2V

NF Noise Floor

PP

PP

[1]

>100kHz

T

MIN

T

MAX

INV Integrated Noise

100kHz to 200MHz

d

Differential Gain

G

d

Differential Phase

P

d

Differential Gain

G

d

Differential Phase

P

VBW -0.1dB Bandwidth

= 100Ω. For other values of R

L

[2]

[2]

[2]

[2]

[2]

[1]

25°C 40.0 57.0 µV

T

MIN

T

MAX

NTSC/PAL 25°C 0.02 % pp

NTSC/PAL 25°C 0.01 ° pp

30MHz 25°C 0.05 % pp

30MHz 25°C 0.05 ° pp

25°C 60.0 MHz

, see curves.

L

EL400C

0.4 dB

0.7 dB

1.0 dB

1.3 dB

1.2 °

2.9 ns

15.0 %

-40.0 dBc

-45.0 dBc

-50.0 dBc

(1Hz)

-154.0 dBm

-153.0 dBm

57.0 µV

63.0 µV

(1Hz)

(1Hz)

EL400C

3

EL400C

200MHz Current Feedback Amplifier

EL400C

Typical Performance Curves

Non-Inverting
Frequency Response

Open-Loop Transimpedance
Gain and Phase

Equivalent Input Noise

Inverting Frequency Response Frequency Response for

2nd and 3rd
Harmonic Distortion

Power-Supply
Rejection Ratio

Various RLs

2-Tone 3rd Order
Intermodulation Intercept

Common-Mode
Rejection Ratio

Settling Time Long-Term Settling Time Settling Time vs Load Capacitance

4

EL400C

200MHz Current Feedback Amplifier

EL400C

Recommended RS vs
Load Capacitance

Pulse Response AV = +2

Pulse Response AV = +2

Differential Gain and
Phase (3.58MHz)

Differential Gain and
Phase (4.43MHz)

5

Differential Gain and
Phase (30MHz)

EL400C

200MHz Current Feedback Amplifier

EL400C

Equivalent Circuit

Burn-In Circuit

All Packages Use The Same Schematic.

6

Applications Information

EL400C

EL400C

200MHz Current Feedback Amplifier

Theory of Operation

The EL400C has a unity gain buffer from the non-invert­ing input to the inverting input. The error signal of the
EL400C is a current flowing into (or out of) the inverting
input. A very small change in current flowing through the
inverting input will cause a large change in the output
voltage. This current amplification is called the trans­impedance (ROL) of the EL400C [V
Since ROL is very large, the current flowing into the
inverting input in the steady-state (non-slewing) condi­tion is very small.

Therefore we can still use op-amp assumptions as a first­order approximation for circuit analysis, namely that:

1. The voltage across the inputs is approximately 0V.

2. The current into the inputs is approximately 0mA.

=(ROL)*(-IIN)].

OUT

Resistor Value Selection and Optimization

The value of the feedback resistor (and an internal
capacitor) sets the AC dynamics of the EL400C. The

nominal value for the feedback resistor is 250Ω, which

is the value used for production testing. This value guar­antees stability. For a given closed-loop gain the
bandwidth may be increased by decreasing the feedback
resistor and, conversely, the bandwidth may be
decreased by increasing the feedback resistor.

Reducing the feedback resistor too much will result in
overshoot and ringing, and eventually oscillations.
Increasing the feedback resistor results in a lower -3dB
frequency. Attenuation at high frequency is limited by a
zero in the closed-loop transfer function which results
from stray capacitance between the inverting input and
ground. Consequently, it is very important to keep stray
capacitance to a minimum at the inverting input.

Differential Gain/Phase

An industry-standard method of measuring the distor­tion of a video component is to measure the amount of
differential gain and phase error it introduces. To mea­sure these, a 40 IREPP reference signal is applied to the
device with 0V DC offset (0IRE) at 3.58MHz for NTSC,

4.43MHz for PAL, and 30MHz for HDTV. A second

measurement is then made with a 0.714V DC offset
(100IRE). Differential Gain is a measure of the change
in amplitude of the sine wave, and is measured in per­cent. Differential Phase is a measure of the change in
phase, and is measured in degrees. Typically, the maxi­mum positive and negative deviations are summed to
give peak values.

In general, a back terminated cable (75Ω in series at the
drive end and 75Ω to ground at the receiving end) is pre-

ferred since the impedance match at both ends will
absorb any reflections. However, when double-termina­tion is used, the received signal is reduced by half;
therefore a gain of 2 configuration is typically used to
compensate for the attenuation. In a gain of 2 configura­tion, with output swing of 2VPP, with each back-

terminated load at 150Ω. The EL400C is capable of

driving up to 4 back-terminated loads with excellent
video performance. Please refer to the typical curves for
more information on video performance with respect to
frequency, gain, and loading.

Capacitive Feedback

The EL400C relies on its feedback resistor for proper
compensation. A reduction of the impedance of the feed­back element results in less stability, eventually
resulting in oscillation. Therefore, circuit implementa­tions which have capacitive feedback should not be used
because of the capacitor's impedance reduction with fre­quency. Similarly, oscillations can occur when using the
technique of placing a capacitor in parallel with the feed­back resistor to compensate for shunt capacitances from
the inverting input to ground.

Offset Adjustment Pin

Output offset voltage of the EL400C can be nulled by
tying a 10k potentiometer between +VS and -VS with the
slider attached to pin 1. A full-range variation of the
voltage at pin 1 to ±5V results in an offset voltage
adjustment of at least ±10mV. For best settling perfor­mance pin 1 should be bypassed to ground with a
ceramic capacitor located near to the package, even if
the offset voltage adjustment feature is not being used.

7

EL400C

200MHz Current Feedback Amplifier

EL400C

Printed Circuit Layout

As with any high frequency device, good PCB layout is
necessary for optimum performance. Ground plane con­struction is a requirement, as is good power-supply and
Offset Adjust bypassing close to the package. The
inverting input is sensitive to stray capacitance, there­fore connections at the inverting input should be
minimal, close to the package, and constructed with as
little coupling the ground plane as possible.

Capacitance at the output node will reduce stability,
eventually resulting in peaking, and finally oscillation if
the capacitance is large enough. The design of the
EL400C allows a larger capacitive load than comparable
products, yet there are occasions when a series resistor
before the capacitance may be needed. Please refer to
the graphs to determine the proper resistor value needed.

8

EL400C Macromodel

* Revision A. March 1992
* Enhancements include PSRR, CMRR, and Slew Rate Limiting
* Connections: +input
* | -input
* | | +Vsupply
* | | | -Vsupply
* | | | | output
* | | | | |
.subckt M400 3 2 7 4 6
*
* Input Stage
*
e1 10 0 3 0 1.0
vis 10 9 0V
h2 9 12 vxx 1.0
r1 2 11 50
l1 11 12 48nH
iinp 3 0 8µA
iinm 2 0 8µA
*
* Slew Rate Limiting
*
h1 13 0 vis 600
r2 13 14 1K
d1 14 0 dclamp
d2 0 14 dclamp
*
* High Frequency Pole
*
*e2 30 0 14 0 0.00166666666
l3 30 17 0.1µH
c5 17 0 0.1pF
r5 17 0 500
*
* Transimpedance Stage
*
g1 0 18 17 0 1.0
rol 18 0 150K
cdp 18 0 2.8pF
*
* Output Stage
*
q1 4 18 19 qp
q2 7 18 20 qn
q3 7 19 21 qn
q4 4 20 22 qp
r7 21 6 2
r8 22 6 2

ios1 7 19 2.5mA
ios2 20 4 2.5mA
*
* Supply Current
*
ips 7 4 9mA
*
* Error Terms
*
ivos 0 23 5mA
vxx 23 0 0V
e4 24 0 3 0 1.0
e5 25 0 7 0 1.0

EL400C

EL400C

200MHz Current Feedback Amplifier

9

EL400C

200MHz Current Feedback Amplifier

EL400C

e6 26 0 4 0 1.0
r9 24 23 3K
r10 25 23 1K
r11 26 23 1K
*
* Models
*
.model qn npn (is=5e-15 bf=200 tf=0.5nS)
.model qp pnp (is=5e-15 bf=200 tf=0.5nS)
.model dclamp d(is=1e-30 ibv=0.266 bv=1.3 n=4)
.ends

EL400C Macromodel

10

EL400C

200MHz Current Feedback Amplifier

EL400C

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.

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-

Elantec Semiconductor, Inc.

675 Trade Zone Blvd.
Milpitas, CA 95035
Telephone: [phone]

(888) ELANTEC
Fax: [phone]
European Office: [phone]
Japan Technical Center: [phone]

port 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 death. Users con­templating 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. Elan­tec, Inc.’s warranty is limited to replacement of defective
components and does not cover injury to persons or property or
other consequential damages.

September 26, 2001

11

Printed in U.S.A.