Elantec EL400C 200mhz current feedback amplifier Datasheet

200MHz Current Feedback Amplifier
Features
General Description
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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.
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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
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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
EL400C
EL400C
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
Temp. Range
Package
Outline #
EL400CN
Part No.
-40°C to +85°C
8-Pin P-DIP
MDP0031
EL400CS
-40°C to +85°C
8-Lead SO
MDP0027
Connection Diagrams
DIP and SO Package
Manufactured under U.S. Patent No. 4,893,091
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.
September 26, 2001
Top View
EL400C
EL400C
200MHz Current Feedback Amplifier
Absolute Maximum Ratings (T
A
= 25°C)
Supply Voltage (VS)
Output Current
±7V
Operating Temperature
Lead Temperature (Soldering, 5 Seconds)
Junction Temperature
Storage Temperature
Thermal Resistance:
θJA = 95°C/W P-DIP
θJA = 175°C/W SO-8
Output is short-circuit protected to ground, however, maximum reliability is obtained if
IOUT does not exceed 70mA.
Common-Mode Input Voltage
Differential Input Voltage
Power Dissipation
±VS
5V
See Curves
-40°C to +85°C
300°C
175°C
-60°C to +150°C
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, RL = 100Ω unless otherwise specified
Parameter
VOS
Description
Test Conditions
Temp
Input Offset Voltage
d(VOS)/dT
Average Offset Voltage Drift
+IIN
+Input Current
Min
Typ
Max
Unit
2.0
5.5
mV
TMIN
8.7
mV
TMAX
9.5
mV
25°C
[1]
All
10.0
40.0
µV/°C
25°C, TMAX
10.0
25.0
µA
TMIN
d(+IIN)/dT
Average +Input Current Drift
-IIN
-Input Current
[1]
[1]
µA
All
50.0
200.0
nA/°C
25°C
10.0
25.0
µA
TMIN
41.0
µA
TMAX
35.0
µA
200.0
nA/°C
d(-IIN)/dT
Average -Input Current Drift
All
PSRR
Power Supply Rejection Ratio
All
40.0
50.0
CMRR
Common-Mode Rejection Ratio
All
40.0
50.0
IS
Supply Current—Quiescent
+RIN
+Input Resistance
No Load
41.0
100.0
All
15.0
25°C, TMAX
100.0
TMIN
50.0
dB
dB
23.0
200.0
mA
kΩ
kΩ
CIN
Input Capacitance
All
0.5
2.0
pF
ROUT
Output Impedance (DC)
All
0.1
0.2
Ω
CMIR
Common-Mode Input Range
IOUT
[2]
Output Current
VOUT
Output Voltage Swing
No Load
VOUTL
Output Voltage Swing
100Ω
ROL
Transimpedance
1. Measured from T MIN to TMAX.
2. Common-Mode Input Range for Rated Performance.
2
25°C, TMAX
2.0
TMIN
1.2
2.1
V
V
25°C, TMAX
50.0
TMIN
35.0
70.0
mA
All
3.2
3.5
25°C
3.0
3.4
V
25°C
30.0
125.0
V/mA
TMIN
80.0
V/mA
TMAX
140.0
V/mA
mA
V
Closed-Loop AC Electrical Characteristics
VS = ±5V, RF = 250Ω, AV = +2, RL = 100Ω unless otherwise specified
Parameter
Frequency
Response
Gain Flatness
Description
SSBW
LSBW
-3dB Bandwidth
(VOUT < 5.0VPP)
AV = +5
GFPL
Peaking
VOUT < 0.5VPP
<40MHz
Peaking
VOUT < 0.5VPP
>40MHz
Rolloff
VOUT < 0.5VPP
<75MHz
GFPH
GFR
LPD
Time-Domain
Response
Test Conditions
-3dB Bandwidth
(VOUT < 0.5VPP)
Temp
Min
Typ
25°C
150.0
200.0
TMIN
150.0
MHz
120.0
MHz
All
35.0
25°C
50.0
0.0
25°C
0.0
TMIN, TMAX
<75MHz
tr1, tf1
Rise Time, Fall Time
0.5V Step
tr2, tf2
Rise Time, Fall Time
5.0V Step
ts1
Settling Time to 0.1%
ts2
OS
25°C
0.6
dB
dB
TMAX
1.3
dB
1.0
°
25°C, TMIN
0.2
°
2.4
ns
2.9
ns
All
6.5
10.0
ns
2.0V Step
All
10.0
13.0
ns
Settling Time to 0.05%
2.0V Step
All
12.0
15.0
ns
Overshoot
0.5V Step
25°C
0.0
10.0
%
25°C, TMIN
HD2
2nd Harmonic Distortion at 20MHz
AV = +2
2VPP
All
15.0
430.0
700.0
All
1600.0
25°C
-60.0
TMIN
TMAX
3rd Harmonic Distortion at 20MHz
2VPP
25°C
-60.0
TMIN, TMAX
Video
Performance
dB
dB
1.6
Slew Rate
INV
0.5
0.7
1.2
SR
NF
dB
dB
1.0
TMAX
AV = - 2
Equivalent Input
Noise
0.3
0.4
1.0
TMAX
HD3
MHz
TMIN
TMIN, TMAX
Distortion
Unit
MHz
TMAX
TMIN, TMAX
Linear Phase Deviation
VOUT < 0.5VPP
Max
Noise Floor
>100kHz
Integrated Noise
100kHz to 200MHz
[1]
V/µs
-45.0
dBc
-40.0
dBc
-45.0
dBc
-50.0
dBc
-50.0
dBc
-154.0
dBm
(1Hz)
TMIN
-154.0
dBm
(1Hz)
TMAX
-153.0
dBm
(1Hz)
25°C
[1]
%
V/µs
25°C
-157.0
57.0
µV
TMIN
40.0
57.0
µV
TMAX
63.0
µV
dG
Differential Gain [2]
NTSC/PAL
25°C
0.02
dP
Differential Phase [2]
NTSC/PAL
25°C
0.01
° pp
dG
Differential Gain [2]
30MHz
25°C
0.05
% pp
dP
Differential Phase [2]
30MHz
25°C
0.05
° pp
VBW
-0.1dB Bandwidth [2]
25°C
60.0
MHz
1. Noise Tests are Performed from 5MHz to 200MHz.
2. Differential Gain/Phase Tests are RL = 100Ω. For other values of RL, see curves.
3
% pp
EL400C
EL400C
200MHz Current Feedback Amplifier
EL400C
EL400C
200MHz Current Feedback Amplifier
Typical Performance Curves
Non-Inverting
Frequency Response
Inverting Frequency Response
Frequency Response for
Various RLs
Open-Loop Transimpedance
Gain and Phase
2nd and 3rd
Harmonic Distortion
2-Tone 3rd Order
Intermodulation Intercept
Equivalent Input Noise
Settling Time
Power-Supply
Rejection Ratio
Long-Term Settling Time
4
Common-Mode
Rejection Ratio
Settling Time vs Load Capacitance
Recommended R S 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
EL400C
200MHz Current Feedback Amplifier
EL400C
EL400C
200MHz Current Feedback Amplifier
Equivalent Circuit
Burn-In Circuit
All Packages Use The Same Schematic.
6
Applications Information
Theory of Operation
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.
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 [VOUT=(ROL)*(-IIN)].
Since ROL is very large, the current flowing into the
inverting input in the steady-state (non-slewing) condition is very small.
In general, a back terminated cable (75Ω in series at the
drive end and 75Ω to ground at the receiving end) is preferred 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 2V PP , with each backterminated 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.
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.
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.
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.
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.
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.
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
7
EL400C
EL400C
200MHz Current Feedback Amplifier
EL400C
EL400C
200MHz Current Feedback Amplifier
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
9
EL400C
EL400C
200MHz Current Feedback Amplifier
EL400C
EL400C
200MHz Current Feedback Amplifier
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
EL400C
200MHz Current Feedback 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 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.
September 26, 2001
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 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 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.
Elantec Semiconductor, Inc.
675 Trade Zone Blvd.
Milpitas, CA 95035
Telephone: (408) 945-1323
(888) ELANTEC
Fax:
(408) 945-9305
European Office: +44-118-977-6020
Japan Technical Center: +81-45-682-5820
11
Printed in U.S.A.
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