Elantec EL2120 100 mhz current feedback amplifier Datasheet

100 MHz Current Feedback Amplifier
Features
General Description
# Excellent differential gain and
phase on g 5V to g 15V supplies
# 100 MHz b 3 dB bandwidth from
gains of g 1 to g 10
# 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 a 5V supply operation
# AC characteristics are lot and
temperature stable
# Available in small SO-8 package
The EL2120C is a wideband current feedback amplifier optimized for video performance. Its 0.01% differential gain and
0.03 degree differential phase performance when at g 5V supplies exceeds the performance of other amplifiers running on
g 15V supplies. Operating on g 8 to g 15V supplies reduces distortions to 0.01% and 0.01 degrees and below. The EL2120C can
operate with supplies as low as g 2.5V or a single a 5V supply.
Applications
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 as a 3 pF load when disabled.
#
#
#
#
#
#
Video gain block
Residue amplifier
Multiplexer
Current to voltage converter
Coax cable driver with gain of 2
ADC driver
EL2120C
EL2120C
Being a current feedback design, bandwidth is a relatively constant 100 MHz over the g 1 to g 10 gain range. The EL2120C
has been optimized for flat gain over frequency and all characteristics are maintained at positive unity gain. Because the input slew rate is similar to the 700 V/ms output slew rate the
part makes an excellent high-speed buffer.
Simplified Schematic
Ordering Information
Part No.
Temp. Range
EL2120CN 0§ C to a 75§ C
EL2120CS
0§ C to a 75§ C
Package
Outline Ý
8-Pin P-DIP MDP0031
8-Lead SO
MDP0027
Connection Diagrams
P-DIP
2120 – 21
2120 – 2
Top View
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.
© 1991 Elantec, Inc.
January 1996 Rev E
2120 – 1
SO
EL2120C
100 MHz Current Feedback Amplifier
Absolute Maximum Ratings (TA e 25§ C)
Voltage between V a and Vb
Voltage at a IN,
b IN, VOUT
Voltage between
a IN and b IN
Voltage at /Disable
Current into a IN,
b IN, and /Disable
Output Current
Internal Power Dissipation
Operating Ambient
Temperature Range
Operating Junction Temperature
P-DIP or SO
Storage Temperature Range
33V
(Vb) b 0.5V to (V a ) a 0.5V
g 5V
(V a ) b 10V to (V a ) a 0.5V
g 50 mA
See Curves
0§ to 75§ C
150§ C
b 65§ C to a 150§ C
g 5 mA
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 TJ e TC e TA.
Test Level
I
II
III
IV
V
Test Procedure
100% production tested and QA sample tested per QA test plan QCX0002.
100% production tested at TA e 25§ C and QA sample tested at TA e 25§ C ,
TMAX and TMIN per QA test plan QCX0002.
QA sample tested per QA test plan QCX0002.
Parameter is guaranteed (but not tested) by Design and Characterization Data.
Parameter is typical value at TA e 25§ C for information purposes only.
Open Loop DC Electrical Characteristics
Parameter
Description
Temp
Min
Typ
Max
Test
Level
Units
20
25
II
II
mV
mV
V
mV/§ C
VOS
Input Offset Voltage
VS e g 15V
Full
Full
4
2
DVOS/DT
Input Offset Drift
Full
20
IB a
a VIN Input Bias Current
Full
5
15
II
mA
IBb
b VIN Input Bias Current
Full
10
50
II
mA
CMRR
Common-Mode Rejection
(Note 1)
Full
II
dB
b ICMR
b Input Current Common-Mode
Rejection (Note 1)
Full
II
mA/V
PSRR
Power Supply Rejection
(Note 2)
Full
80
II
dB
a IPSR
a Input Current Power Supply
Rejection (Note 2)
25§ C
0.03
V
mA/V
b IPSR
b Input Current Power Supply
Rejection (Note 2)
Full
0.6
II
mA/V
ROL
Transimpedance
Full
70
140
II
kX
AVOL
Voltage Gain
Full
58
66
II
dB
a RIN
a VIN Input Impedance
25§ C
2
V
MX
2
50
55
8
65
20
5
TD is 3.2in
VS e g 5V; RL e 150X, TA e 25§ C unless otherwise specified
EL2120C
100 MHz Current Feedback Amplifier
Open Loop DC Electrical Characteristics Ð Contd.
Parameter
Description
Temp
Min
Typ
Max
Test
Level
Units
VIN
a VIN Range
Full
g 3.0
g 3.5
II
V
VO
Output Voltage Swing
Full
g 3.0
g 3.5
II
V
ISC
Output Short-Circuit
Current
25§ C
100
II
mA
IO,DIS
Output Current, Disabled
Full
5
II
mA
VDIS,ON
Disable Pin Voltage for
Output Enabled
Full
II
V
VDIS,OFF
Disable Pin Voltage for
Output Disabled
Full
(V a ) b 4
II
V
IDIS,ON
Disable Pin Current for
Output Enabled
Full
5
II
mA
IDIS,OFF
Disable Pin Current for
Output Disabled
Full
II
mA
IS
Supply Current (VS e g 15V)
Full
20
II
mA
Max
Test
Level
Units
50
(V a ) b 1
1.0
17
TD is 2.7in
VS e g 5V; RL e 150X, TA e 25§ C unless otherwise specified
Note 1: The input is moved from b3V to a 3V.
Note 2: The supplies are moved from g 5V to g 15V.
Closed Loop AC Electrical Characteristics
Parameter
SR
tS
BW
Description
Min
Slew Rate; VOUT from b3V to a 3V
Measured at b2V and a 2V
VS e g 15V
VS e g 5V
750
550
V
V
V/ms
V/ms
Settling Time to 0.25% of a
0 to a 10V Swing; AV e a 1 with
RF e 270X, RG e % , and RL e 400X
50
V
ns
95
50
16
V
V
V
MHz
MHz
MHz
75
35
11
V
V
V
MHz
MHz
MHz
0.5
V
dB
Bandwidth
b 3 dB
g 1 dB
g 0.1 dB
BW @ 2.5V
Typ
Bandwidth at
VS e g 2.5V
b 3 dB
g 1 dB
g 0.1 dB
Peaking
3
TD is 2.4in
VS e g 15V; AV e a 2 (RF e RG e 270X); RL e 150X; CL e 7 pF; CINb e 2 pF; TA e 25§ C
EL2120C
100 MHz Current Feedback Amplifier
Closed Loop AC Electrical Characteristics Ð Contd.
Parameter
dG
di
Description
Min
Test
Level
Units
0.1
0.01
V
V
V
%
%
%
0.01
0.1
0.06
V
V
V
§
§
§
Typ
Differential Gain; DC Offset
from b0.7V through a 0.7V, AC
Amplitude 286 mVp–p
VS e g 15V, f e 3.58 MHz
VS e g 15V, f e 30 MHz
VS e g 5V, f e 3.58 MHz
k 0.01
Differential Phase; DC Offset
from b0.7V through a 0.7V, AC
Amplitude 286 mVp–p
VS e g 15V, f e 3.58 MHz
VS e g 15V, f e 30 MHz
VS e g 5V, f e 3.58 MHz
Max
Typical Performance Curves
AC Test Circuit
2120 – 3
Frequency Response vs RF
Frequency Response vs Gain
2120 – 4
2120 – 5
4
Frequency Response vs Load
2120 – 6
TD is 2.0in
VS e g 15V; AV e a 2 (RF e RG e 270X); RL e 150X; CL e 7 pF; CINb e 2 pF; TA e 25§ C
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves Ð Contd.
Gain Flatness vs RF
Gain Flatness vs CIN b
b 3 dB Bandwidth, 0.1 dB Bandwidth,
and Peaking vs Temperature
at VS g 15V
b 3 dB Bandwidth, 0.1 dB Bandwidth,
and Peaking vs Temperature
at VS g 5V
b 3 dB Bandwidth,
0.1 dB Bandwidth, and
Peaking vs Supply Voltage
Deviation From Linear
Phase vs Frequency
2120 – 7
5
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves Ð Contd.
Differential Gain vs
DC Input Offset
at 3.58 MHz
Differential Phase vs
DC Input Offset
at 3.58 MHz
Differential Gain vs
DC Input Offset
at 30 MHz
Differential Phase vs
DC Input Offset
at 30 MHz
Differential Gain and Phase
vs Supply Voltage
(VIN, DC from 0 to a 0.7V)
Input Noise Voltage
and Current
2120 – 8
6
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves Ð Contd.
Undistorted Output
Swing vs Frequency
Slew Rate vs Temperature
2120 – 9
Small-Signal Transient Response
AV e a 2, RF e RG e 270X,
RL e 150X
Large-Signal Transient Response
2120 – 10
AV e a 2, RF e RG e 270X,
RL e 150X, VS e g 15V
Settling Time vs Swing
2120 – 11
Long Term Settling Error
2120 – 12
7
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves Ð Contd.
Enable Response for
a Family of Inputs
AV e a 2, RL e 150X,
VS e g 5V
Disable Response for
a Family of Inputs
2120 – 13
AV e a 2, RL e 150X,
VS e g 5V
2120 – 14
8-Pin Plastic DIP
Maximum Power Dissipation
vs Ambient Temperature
Supply Current vs
Supply Voltage
8-Lead SO
Maximum Power Dissipation
vs Ambient Temperature
2120 – 15
8
EL2120C
100 MHz Current Feedback Amplifier
The greatest frequency response flatness (to
0.1 dB, for instance) occurs with RF e 300X to
330X. Even the moderate peaking caused by lower values of RF will cause the gain to peak out of
the 0.1 dB window, and higher values of RF will
cause an overcompensated response where the
gain falls below the 0.1 dB level. Parasitic capacitances will generally degrade the frequency flatness.
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, temperature, and manufacturing lot variations. It is
a well-behaved amplifier in spite of its 100 MHz
bandwidth, but a few precautions should be taken to obtain maximum performance.
The EL2120C should not output a continuous
current above 50 mA, as stated in the ABSOLUTE MAXIMUM RATINGS table. The output current limit is set to 120 mA at a die temperature of 25§ C and reduces to 85 mA at a die temperature of 150§ C. This large current is needed to
slew load capacitance and drive low impedance
loads with low distortion but cannot be supported continuously. Furthermore, package dissipation capabilities cannot be met under short-circuit conditions. Current limit should not occur
longer than a few seconds.
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 characteristics, and smaller capacitors in parallel will
not be needed. The lead length of sockets generally deteriorates the amplifier’s frequency response
by exaggerating peaking and increasing ringing
in response to transients. Short sockets cause little degradation.
Load capacitance also increases ringing and
peaking. Capacitance greater than 35 pF should
be isolated with a series resistor. Capacitance at
the VIN b terminal has a similar effect, and
should be kept below 5 pF. Often, the inductance
of the leads of a load capacitance will be self-resonant 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 resonances. 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 output disable function of the EL2120C is
optimized for video performance. While in disable mode, the feedthrough of the circuit can be
modeled as a 0.2 pF capacitor from VIN a to the
output. No more than g 5V can be placed between VIN a and VIN b in 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 without the output transistors turning on.
The /Disable pin logic level is referred to V a .
With g 5V supplies, a CMOS or TTL driver with
pull-up resistor will suffice. g 15V supplies require a a 14/ a 11V drive span, or a 15/ a 10V
nominally. Open-collector TTL with a tapped
pull-up resistor can provide these spans. The impedance of the divider should be 1k or less for
optimum enable/disable speed.
The VIN a pin can oscillate in the 200 MHz to
500 MHz realm if presented with a resonant or
inductive source impedance. A series 27X to 68X
resistor right on the VIN a pin will suppress such
oscillations without affecting frequency response.
The EL2120C enables in 50 ns or less. When VIN
e 0, only a small switching glitch occurs at the
output. When VIN is some other value, the output overshoots by about 0.7V when settling
toward its new enabled value.
b 3 dB bandwidth is inversely proportional to
the value of feedback resistor RF. The EL2120C
will tolerate values as low as 180X for a maximum bandwidth of about 140 MHz, but peaking
will increase and tolerance to stray capacitance
will reduce. At gains greater than 5, b 3 dB bandwidth begins to reduce, and a smaller RF can be
used to maximize frequency response.
9
EL2120C
100 MHz Current Feedback Amplifier
Applications Information Ð Contd.
When the EL2120C disables, it turns off very rapidly for inputs of g 1V or less, and the output sags
more slowly for inputs larger than this. For inputs as large as g 2.5V the output current can be
absorbed by another EL2120C simultaneously enabled. Under these conditions, switching will be properly completed in 50 ns or less.
The greater thermal resistance of the SO-8 package requires that the EL2120C be operated from g 10V
supplies or less to maintain the 150§ C maximum die temperature over the commercial temperature
range. The P-DIP package allows the full g 16.5V supply operation.
Typical Applications CircuitÐA High Quality Two-Input Multiplexer
Channel-to-Channel Isolation
of Dual EL2120C Multiplexer
Dual EL2120C Multiplexer
2120 – 17
2120 – 16
Dual EL2120C Multiplexer Switching
Channels: Uncorrelated Sinewave
Switched to a Family of DC Levels
Dual EL2120C Multiplexer Switching
Channels: a Family of DC Levels
Switched to an Uncorrelated Sinewave
2120 – 19
2120 – 18
10
T
EL2120C
100 MHz Current Feedback Amplifier
The EL2120C Macromodel
* Revision A. March 1992
* Enhancements include PSRR, CMRR, and Slew Rate Limiting
a input
* Connections:
b input
*
l
a Vsupply
*
l
l
b Vsupply
*
l
l
l
output
*
l
l
l
l
*
l
l
l
l
l
.subckt M2120
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 25
l1 11 12 20nH
iinp 3 0 10mA
iinm 2 0 5mA
r12 3 0 2Meg
*
* Slew Rate Limiting
*
h1 13 0 vis 600
r2 13 14 1K
d1 14 0 dclamp
s2 0 14 dclamp
*
* High Frequency Pole
*
e2 30 0 14 0 0.00166666666
15 30 17 1mH
c5 17 0 0.5pF
r5 17 0 600
*
* Transimpedance Stage
*
g1 0 18 17 0 1.0
rol 18 0 140K
cdp 18 0 7.9pF
*
* 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 4
r8 22 6 4
ios1 7 19 2.5mA
ios2 20 4 2.5mA
*
* Supply
*
ips 7 4 10mA
*
* Error Terms
*
ivos 0 23 5mA
vxx 23 0 0V
e4 24 0 6 0 1.0
e5 25 0 7 0 1.0
e6 26 0 4 0 1.0
r9 24 23 562
r10 25 23 10K
r11 26 23 10K
*
* Models
*
.model qn npn (is e 5eb15 bf e 500 tf e 0.1nS)
.model qp pnp (is e 5eb15 bf e 500 tf e 0.1nS)
.model dclamp d(is e 1eb30 ibv e 0.02 bv e 4 n e 4)
.ends
11
TD is 3.8in
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
TAB WIDE
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.
EL2120C
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.
January 1996 Rev E
WARNING Ð 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, Inc.
1996 Tarob Court
Milpitas, CA 95035
Telephone: (408) 945-1323
(800) 333-6314
Fax: (408) 945-9305
European Office: 44-71-482-4596
12
Printed in U.S.A.
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