Page 1
EL2120C
100 MHz Current Feedback Amplifier
EL2120C January 1996 Rev E
Features
# Excellent differential gain and
phase on
# 100 MHz
gains of
# 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
# AC characteristics are lot and
temperature stable
# Available in small SO-8 package
g
5V tog15V supplies
b
3 dB bandwidth from
g
1tog10
a
5V supply operation
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
EL2120CN 0§Ctoa75§C 8-Pin P-DIP MDP0031
EL2120CS 0§Ctoa75§C 8-Lead SO MDP0027
General Description
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
plies exceeds the performance of other amplifiers running on
g
15V supplies. Operating ong8tog15V 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 singlea5V supply.
Being a current feedback design, bandwidth is a relatively constant 100 MHz over the
g
1tog10 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.
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
Ý
g
5V sup-
Connection Diagrams
P-DIP
2120– 1
SO
2120– 21
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.
2120– 2
Page 2
EL2120C
100 MHz Current Feedback Amplifier
Absolute Maximum Ratings
a
Voltage between V
a
Voltage at
b
Voltage between
a
IN,
IN, V
OUT
IN andbIN
Voltage at /Disable (V
a
Current into
b
IN, and /Disable
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
IN,
I 100% production tested and QA sample tested per QA test plan QCX0002.
II 100% production tested at T
III QA sample tested per QA test plan QCX0002.
IV Parameter is guaranteed (but not tested) by Design and Characterization Data.
V Parameter is typical value at T
and V
T
MAX
b
(Vb)b0.5V to (Va)a0.5V
a)b
10V to (Va)a0.5V
and T
MIN
A
per QA test plan QCX0002.
e
(T
25§C)
A
Output Current
33V
Internal Power Dissipation See Curves
Operating Ambient
Temperature Range 0
g
5V
Operating Junction Temperature
P-DIP or SO 150
Storage Temperature Range
g
5mA
e
25§C and QA sample tested at T
e
25§C for information purposes only.
A
g
50 mA
to 75§C
§
b
65§Ctoa150§C
e
e
T
TA.
J
C
e
25§C,
A
§
Open Loop DC Electrical Characteristics
e
g
V
S
Parameter Description Temp Min Typ Max
V
OS
DVOS/DT Input Offset Drift Full 20 V mV/§C
I
a
B
I
b
B
CMRR Common-Mode Rejection
b
ICMR
PSRR Power Supply Rejection
a
IPSR
b
IPSR
R
OL
A
VOL
a
R
5V; R
IN
L
e
150X,T
e
25§C unless otherwise specified
A
Input Offset Voltage Full 4 20 II mV
e
g
15V Full 2 25 II mV
V
S
a
VINInput Bias Current Full 5 15 II mA
b
VINInput Bias Current Full 10 50 II mA
(Note 1)
b
Input Current Common-Mode
Rejection (Note 1)
(Note 2)
a
Input Current Power Supply
Rejection (Note 2)
b
Input Current Power Supply
Rejection (Note 2)
Full 50 55 II dB
Full 8 20 II mA/V
Full 65 80 II dB
C 0.03 V mA/V
25
§
Full 0.6 5 II mA/V
Transimpedance Full 70 140 II kX
Voltage Gain Full 58 66 II dB
a
VINInput Impedance 25§C2 VMX
Test
Level
Units
C
TDis 3.2in
2
Page 3
EL2120C
100 MHz Current Feedback Amplifier
Open Loop DC Electrical Characteristics
e
V
S
Parameter Description Temp Min Typ Max
V
IN
V
O
I
SC
I
O,DIS
V
DIS,ON
V
DIS,OFF
I
DIS,ON
I
DIS,OFF
I
S
g
5V; R
L
e
150X,T
e
25§C unless otherwise specified
A
a
VINRange Full
Output Voltage Swing Full
Output Short-Circuit
Current
25
C 100 II mA
§
Output Current, Disabled Full 5 50 II mA
Disable Pin Voltage for
Output Enabled
Disable Pin Voltage for
Output Disabled
Disable Pin Current for
Output Enabled
Disable Pin Current for
Output Disabled
Supply Current (V
e
S
g
15V) Full 17 20 II mA
Full (V
Full (V
Full 5 II mA
Full 1.0 II mA
Ð Contd.
Test
Level
g
3.0
g
3.0
a)b
g
3.5 II V
g
3.5 II V
1IIV
a)b
4II V
Note 1: The input is moved fromb3V toa3V.
g
Note 2: The supplies are moved from
5V tog15V.
Closed Loop AC Electrical Characteristics
e
g
V
S
Parameter Description Min Typ Max
SR Slew Rate; V
t
S
BW Bandwidth
BW@2.5V Bandwidth at
Peaking 0.5 V dB
15V; A
V
ea
2(R
e
R
F
Measured at
Settling Time to 0.25% of a
a
0to
10V Swing; A
e
R
270X,R
F
e
g
V
2.5V
S
e
270X); R
G
fromb3V toa3V
OUT
b
2V anda2V
e %
G
ea
V
, and R
L
e
150X;C
e
7 pF; C
L
e
g
V
15V 750 V V/ms
S
e
g
V
5V 550 V V/ms
S
e
b
IN
2 pF; T
e
25§C
A
1 with
e
400X 50 V ns
L
b
3 dB 95 V MHz
g
1 dB 50 V MHz
g
0.1 dB 16 V MHz
b
3 dB 75 V MHz
g
1 dB 35 V MHz
g
0.1 dB 11 V MHz
Test
Level
Units
TDis 2.7inTDis 2.4in
Units
3
Page 4
EL2120C
100 MHz Current Feedback Amplifier
Closed Loop AC Electrical Characteristics
e
g
V
S
15V; A
V
ea
2(R
e
e
R
G
270X); R
F
L
e
150X;C
e
7 pF; C
L
b
IN
Ð Contd.
e
2 pF; T
e
25§C
A
Parameter Description Min Typ Max
dG Differential Gain; DC Offset
b
from
0.7V througha0.7V, AC
Amplitude 286 mVp –p
e
g
V
15V, fe3.58 MHz
S
e
g
V
15V, fe30 MHz 0.1 V %
S
e
g
V
5V, fe3.58 MHz 0.01 V %
S
k
0.01 V %
di Differential Phase; DC Offset
b
from
0.7V througha0.7V, AC
Amplitude 286 mVp –p
e
g
V
15V, fe3.58 MHz 0.01 V
S
e
g
V
15V, fe30 MHz 0.1 V
S
e
g
V
5V, fe3.58 MHz 0.06 V
S
Typical Performance Curves
AC Test Circuit
Test
Level
Units
§
§
§
TDis 2.0in
Frequency Response vs R
F
2120– 4
Frequency Response vs Gain
2120– 5
4
2120– 3
Frequency Response vs Load
2120– 6
Page 5
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves
Gain Flatness vs R
b
3 dB Bandwidth, 0.1 dB Bandwidth,
and Peaking vs Temperature
g
at V
15V
S
F
Ð Contd.
Gain Flatness vs C
b
3 dB Bandwidth, 0.1 dB Bandwidth,
and Peaking vs Temperature
g
at V
5V
S
b
IN
b
3 dB Bandwidth,
0.1 dB Bandwidth, and
Peaking vs Supply Voltage
Deviation From Linear
Phase vs Frequency
2120– 7
5
Page 6
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves
Differential Gain vs
DC Input Offset
at 3.58 MHz
Differential Gain vs
DC Input Offset
at 30 MHz
Ð Contd.
Differential Phase vs
DC Input Offset
at 3.58 MHz
Differential Phase vs
DC Input Offset
at 30 MHz
Differential Gain and Phase
vs Supply Voltage
,DCfrom0toa0.7V)
(V
IN
Input Noise Voltage
and Current
2120– 8
6
Page 7
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves
Undistorted Output
Swing vs Frequency
Small-Signal Transient Response
Ð Contd.
Slew Rate vs Temperature
2120– 9
Large-Signal Transient Response
ea
A
V
e
R
L
e
2, R
150X
Settling Time vs Swing Long Term Settling Error
e
R
F
270X,
G
2120– 10
ea
A
V
e
R
L
2, R
150X,V
e
e
R
e
270X,
G
g
15V
F
S
2120– 11
2120– 12
7
Page 8
EL2120C
100 MHz Current Feedback Amplifier
Typical Performance Curves
Enable Response for
a Family of Inputs
ea
A
V
e
V
S
Supply Current vs Maximum Power Dissipation
Supply Voltage
e
2, R
150X,
L
g
5V
Ð Contd.
2120– 13
Disable Response for
a Family of Inputs
ea
A
V
e
V
S
8-Pin Plastic DIP
vs Ambient Temperature
e
2, R
L
g
5V
150X,
2120– 14
8-Lead SO
Maximum Power Dissipation
vs Ambient Temperature
8
2120– 15
Page 9
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, 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 power supply pins must be well bypassed.
0.01 mF ceramic capacitors are adequate, but lead
length should be kept below (/4
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 V
terminal has a similar effect, and
b
IN
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 V
pin can oscillate in the 200 MHz to
a
IN
500 MHz realm if presented with a resonant or
inductive source impedance. A series 27X to 68X
resistor right on the V
pin will suppress such
a
IN
oscillations without affecting frequency response.
b
3 dB bandwidth is inversely proportional to
the value of feedback resistor R
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,
width begins to reduce, and a smaller R
used to maximize frequency response.
and a ground
×
. The EL2120C
F
b
3 dB band-
can be
F
The greatest frequency response flatness (to
e
0.1 dB, for instance) occurs with R
F
300X to
330X. Even the moderate peaking caused by lower values of R
the 0.1 dB window, and higher values of R
will cause the gain to peak out of
F
will
F
cause an overcompensated response where the
gain falls below the 0.1 dB level. Parasitic capacitances will generally degrade the frequency flatness.
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
perature of 150
C and reduces to 85 mA at a die tem-
§
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 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 V
output. No more than
tween V
IN
a
and V
g
5V can be placed be-
in disable mode, but this
b
IN
IN
a
to the
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
g
With
pull-up resistor will suffice.
quire a
5V supplies, a CMOS or TTL driver with
g
a
14/a11V drive span, ora15/a10V
15V supplies re-
a
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 EL2120C enables in 50 ns or less. When V
e
0, only a small switching glitch occurs at the
output. When V
is some other value, the out-
IN
IN
put overshoots by about 0.7V when settling
toward its new enabled value.
.
9
Page 10
EL2120C
100 MHz Current Feedback Amplifier
Applications Information
When the EL2120C disables, it turns off very rapidly for inputs of
more slowly for inputs larger than this. For inputs as large as
Ð Contd.
g
1V or less, and the output sags
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
supplies or less to maintain the 150
range. The P-DIP package allows the full
C maximum die temperature over the commercial temperature
§
g
16.5V supply operation.
g
10V
Typical Applications CircuitÐA High Quality Two-Input Multiplexer
Dual EL2120C Multiplexer
Channel-to-Channel Isolation
of Dual EL2120C Multiplexer
2120– 17
Dual EL2120C Multiplexer Switching
2120– 16
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
10
Page 11
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:
*
*
*
*
*
.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 (is
rol 18 0 140K .model qp pnp (is
cdp 18 0 7.9pF .model dclamp d(is
* .ends
* Output Stage
a
input
b
input
l
ll
lll
llll
a
Vsupply
b
Vsupply
output
lllll
11
e5eb
15 bfe500 tfe0.1nS)
e5eb
15 bfe500 tfe0.1nS)
e1eb
30 ibve0.02 bve4ne4)
TABWIDE
TDis 3.8in TD
Page 12
EL2120C
100 MHz Current Feedback Amplifier
EL2120CJanuary 1996 Rev E
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.
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 in-
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
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
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.
Printed in U.S.A.12
Loading...