1
TM
File Number
2992.6
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
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Intersil and Design is a trademark of Intersil Corporation.
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Copyright Intersil Corporation 2000
HFA1112, HFA1112A
850MHz, Low Distortion Programmable
Gain Buffer Amplifiers
The HFA1112/12A are closed loop Buffers featuring user
programmable gain and ultra high speed performance.
Manufactured on Intersil's proprietary complementary
bipolar UHF-1 process, these devices offer a wide -3dB
bandwidth of 850MHz, very fast slew rate, excellent gain
flatness, low distortion and high output current. The
HFA1112A is a more stable version optimized for unity gain
applications.
A unique feature of the pinout allows the user to select a
voltage gain of +1, -1, or +2, without the use of any external
components. Gain selection is accomplished via
connections to the inputs, as described in the "Application
Information" section. The result is a more flexible product,
fewer part types in inventory, and more efficient use of board
space.
Compatibility with existing op amp pinouts provides flexibility
to upgrade low gain amplifiers, while decreasing component
count. Unlike most buffers, the standard pinout provides an
upgrade path should a higher closed loop gain be needed at
a future date.
This amplifier is available with programmable output limiting
as the HFA1113. For applications requiring a standard buffer
pinout, please refer to the HFA1110 data sheet.
HFA1112 (PDIP, SOIC)
HFA1112A (SOIC)
TOP VIEW
Features
User Programmable for Closed-Loop Gains of +1, -1 or +2
without Use of External Resistors
HFA1112A Optimized for A
V
= 1 Applications
Wide -3dB Bandwidth. . . . . . . . . . . . . . . . . . . . . . 850MHz
Very Fast Slew Rate . . . . . . . . . . . . . . . . . . . . . . 2400V/
s
Fast Settling Time (0.1%) . . . . . . . . . . . . . . . . . . . . . 11ns
High Output Current . . . . . . . . . . . . . . . . . . . . . . . . . 60mA
Excellent Gain Accuracy . . . . . . . . . . . . . . . . . . . 0.99V/V
Overdrive Recovery . . . . . . . . . . . . . . . . . . . . . . . . <10ns
Standard Operational Amplifier Pinout
Applications
RF/IF Processors
Driving Flash A/D Converters
High-Speed Communications
Impedance Transformation
Line Driving
Video Switching and Routing
Radar Systems
Medical Imaging Systems
Related Literature
- AN9507, Video Cable Drivers Save Board Space
Related Literature
Technical Brief TB363 "Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices
(SMDs)"
Pin Descriptions
NAME
PIN NUMBER
DESCRIPTION
NC
1, 5, 8
No Connection
-IN
2
Inverting Input
+IN
3
Non-Inverting Input
V-
4
Negative Supply
OUT
6
Output
V+
7
Positive Supply
NC
-IN
+IN
V-
1
2
3
4
8
7
6
5
NC
V+
OUT
NC
+
300
300
-
Ordering Information
PART NUMBER
(BRAND)
TEMP.
RANGE (
o
C)
PACKAGE
PKG.
NO.
HFA1112IP
-40 to 85
8 Ld PDIP
E8.3
HFA1112IB
(1112I)
-40 to 85
8 Ld SOIC
M8.15
HFA1112AIB
(1112AIB)
-40 to 85
8 Ld SOIC
M8.15
HFA11XXEVAL
High Speed Op Amp DIP Evaluation Board
Data Sheet
December 2000
2
Absolute Maximum Ratings
Thermal Information
Voltage Between V+ and V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
SUPPLY
Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60mA
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . -40
o
C to 85
o
C
Thermal Resistance (Typical, Note 1)
JA
(
o
C/W)
JC
(
o
C/W)
PDIP Package . . . . . . . . . . . . . . . . . . .
125
N/A
SOIC Package . . . . . . . . . . . . . . . . . . .
170
N/A
Maximum Junction Temperature (Plastic Package) . . . . . . . .150
o
C
Maximum Storage Temperature Range . . . . . . . . . . -65
o
C to 150
o
C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300
o
C
(SOIC - Lead Tips Only)
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
1.
JA
is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
Electrical Specifications
V
SUPPLY
=
5V, A
V
= +1, R
L
= 100
, Unless Otherwise Specified
PARAMETER
TEST CONDITIONS
TEMP (
o
C)
MIN
TYP
MAX
UNITS
INPUT CHARACTERISTICS
Output Offset Voltage
25
-
8
25
mV
Full
-
-
35
mV
Output Offset Voltage Drift
Full
-
10
-
V/
o
C
PSRR
25
39
45
-
dB
Full
35
-
-
dB
Input Noise Voltage (Note 3)
100kHz
25
-
9
-
nV/
Hz
Non-Inverting Input Noise Current (Note 3)
100kHz
25
-
37
-
pA/
Hz
Non-Inverting Input Bias Current
25
-
25
40
A
Full
-
-
65
A
Non-Inverting Input Resistance
25
25
50
-
k
Inverting Input Resistance (Note 2)
25
240
300
360
Input Capacitance
25
-
2
-
pF
Input Common Mode Range
Full
2.5
2.8
-
V
TRANSFER CHARACTERISTICS
Gain
A
V
= +1, V
IN
= +2V
25
0.980
0.990
1.02
V/V
Full
0.975
-
1.025
V/V
Gain
A
V
= +2, V
IN
= +1V
25
1.96
1.98
2.04
V/V
Full
1.95
-
2.05
V/V
DC Non-Linearity (Note 3)
A
V
= +2,
2V Full Scale
25
-
0.02
-
%
OUTPUT CHARACTERISTICS
Output Voltage (Note 3)
A
V
= -1
25
3.0
3.3
-
V
Full
2.5
3.0
-
V
Output Current (Note 3)
R
L
= 50
25, 85
50
60
-
mA
-40
35
50
-
mA
Closed Loop Output Impedance
DC, A
V
= +2
25
-
0.3
-
POWER SUPPLY CHARACTERISTICS
Supply Voltage Range
Full
4.5
-
5.5
V
Supply Current (Note 3)
25
-
21
26
mA
Full
-
-
33
mA
AC CHARACTERISTICS
-3dB Bandwidth
(V
OUT
= 0.2V
P-P
, Notes 2, 3)
A
V
= -1
25
450
800
-
MHz
A
V
= +1
25
500
850
-
MHz
A
V
= +2
25
350
550
-
MHz
HFA1112, HFA1112A
3
Slew Rate
(V
OUT
= 5V
P-P
, Note 2)
A
V
= -1
25
1500
2400
-
V/
s
A
V
= +1
25
800
1500
-
V/
s
A
V
= +2
25
1100
1900
-
V/
s
Full Power Bandwidth
(V
OUT
= 5V
P-P
, Note 3)
A
V
= -1
25
-
300
-
MHz
A
V
= +1
25
-
150
-
MHz
A
V
= +2
25
-
220
-
MHz
Gain Flatness
(to 30MHz, Notes 2, 3)
A
V
= -1
25
-
0.02
-
dB
A
V
= +1
25
-
0.1
-
dB
A
V
= +2
25
-
0.015
0.04
dB
Gain Flatness
(to 50MHz, Notes 2, 3)
A
V
= -1
25
-
0.05
-
dB
A
V
= +1
25
-
0.2
-
dB
A
V
= +2
25
-
0.036
0.08
dB
Gain Flatness
(to 100MHz, Notes 2, 3)
A
V
= -1
25
-
0.10
-
dB
A
V
= +2
25
-
0.07
0.22
dB
Linear Phase Deviation
(to 100MHz, Note 3)
A
V
= -1
25
-
0.13
-
Degrees
A
V
= +1
25
-
0.83
-
Degrees
A
V
= +2
25
-
0.05
-
Degrees
2nd Harmonic Distortion
(30MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-52
-
dBc
A
V
= +1
25
-
-57
-
dBc
A
V
= +2
25
-
-52
-45
dBc
3rd Harmonic Distortion
(30MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-71
-
dBc
A
V
= +1
25
-
-73
-
dBc
A
V
= +2
25
-
-72
-65
dBc
2nd Harmonic Distortion
(50MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-47
-
dBc
A
V
= +1
25
-
-53
-
dBc
A
V
= +2
25
-
-47
-40
dBc
3rd Harmonic Distortion
(50MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-63
-
dBc
A
V
= +1
25
-
-68
-
dBc
A
V
= +2
25
-
-65
-55
dBc
2nd Harmonic Distortion
(100MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-41
-
dBc
A
V
= +1
25
-
-50
-
dBc
A
V
= +2
25
-
-42
-35
dBc
3rd Harmonic Distortion
(100MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
25
-
-55
-
dBc
A
V
= +1
25
-
-49
-
dBc
A
V
= +2
25
-
-62
-45
dBc
3rd Order Intercept
(A
V
= +2, Note 3)
100MHz
25
-
28
-
dBm
300MHz
25
-
13
-
dBm
1dB Compression
(A
V
= +2, Note 3)
100MHz
25
-
19
-
dBm
300MHz
25
-
12
-
dBm
Reverse Isolation
(S
12
, Note 3)
40MHz
25
-
-70
-
dB
100MHz
25
-
-60
-
dB
600MHz
25
-
-32
-
dB
TRANSIENT CHARACTERISTICS
Rise Time
(V
OUT
= 0.5V Step, Note 2)
A
V
= -1
25
-
500
800
ps
A
V
= +1
25
-
480
750
ps
A
V
= +2
25
-
700
1000
ps
Electrical Specifications
V
SUPPLY
=
5V, A
V
= +1, R
L
= 100
, Unless Otherwise Specified (Continued)
PARAMETER
TEST CONDITIONS
TEMP (
o
C)
MIN
TYP
MAX
UNITS
HFA1112, HFA1112A
4
Application Information
Closed Loop Gain Selection
The HFA1112 features a novel design which allows the user
to select from three closed loop gains, without any external
components. The result is a more flexible product, fewer part
types in inventory, and more efficient use of board space.
This "buffer" operates in closed loop gains of -1, +1, or +2, and
gain selection is accomplished via connections to the
inputs.
Applying the input signal to +IN and floating -IN selects a gain
of +1, while grounding -IN selects a gain of +2. A gain of -1 is
obtained by applying the input signal to -IN with +IN grounded.
The table below summarizes these connections:
PC Board Layout
The frequency response of this amplifier depends greatly on
the amount of care taken in designing the PC board. The
use of low inductance components such as chip
resistors and chip capacitors is strongly recommended,
while a solid ground plane is a must!
Attention should be given to decoupling the power supplies.
A large value (10
F) tantalum in parallel with a small value
(0.1
F) chip capacitor works well in most cases.
Terminated microstrip signal lines are recommended at the
input and output of the device. Capacitance directly on the
output must be minimized, or isolated as discussed in the
next section.
For unity gain applications, care must also be taken to
minimize the capacitance to ground seen by the amplifier's
inverting input. At higher frequencies this capacitance will
tend to short the -INPUT to GND, resulting in a closed loop
gain which increases with frequency. This will cause
excessive high frequency peaking and potentially other
problems as well.
An example of a good high frequency layout is the
Evaluation Board shown in Figure 2.
Driving Capacitive Loads
Capacitive loads, such as an A/D input, or an improperly
terminated transmission line will degrade the amplifier's
phase margin resulting in frequency response peaking and
possible oscillations. In most cases, the oscillation can be
avoided by placing a resistor (R
S
) in series with the output
prior to the capacitance.
Figure 1 details starting points for the selection of this
resistor. The points on the curve indicate the R
S
and C
L
combinations for the optimum bandwidth, stability, and
settling time, but experimental fine tuning is recommended.
Picking a point above or to the right of the curve yields an
overdamped response, while points below or left of the curve
indicate areas of underdamped performance.
R
S
and C
L
form a low pass network at the output, thus
limiting system bandwidth well below the amplifier
bandwidth of 850MHz. By decreasing R
S
as C
L
increases
Rise Time
(V
OUT
= 2V Step)
A
V
= -1
25
-
0.82
-
ns
A
V
= +1
25
-
1.06
-
ns
A
V
= +2
25
-
1.00
-
ns
Overshoot
(V
OUT
= 0.5V Step, Input t
R
/t
F
= 200ps,
Notes 2, 3, 4)
A
V
= -1
25
-
12
30
%
A
V
= +1
25
-
45
65
%
A
V
= +2
25
-
6
20
%
0.1% Settling Time (Note 3)
V
OUT
= 2V to 0V
25
-
11
-
ns
0.05% Settling Time
V
OUT
= 2V to 0V
25
-
15
-
ns
Overdrive Recovery Time
V
IN
= 5V
P-P
25
-
8.5
-
ns
Differential Gain
A
V
= +1, 3.58MHz, R
L
= 150
25
-
0.03
-
%
A
V
= +2, 3.58MHz, R
L
= 150
25
-
0.02
-
%
Differential Phase
A
V
= +1, 3.58MHz, R
L
= 150
25
-
0.05
-
Degrees
A
V
= +2, 3.58MHz, R
L
= 150
25
-
0.04
-
Degrees
NOTES:
2. This parameter is not tested. The limits are guaranteed based on lab characterization, and reflect lot-to-lot variation.
3. See Typical Performance Curves for more information.
4. Overshoot decreases as input transition times increase, especially for A
V
= +1. Please refer to Typical Performance Curves.
Electrical Specifications
V
SUPPLY
=
5V, A
V
= +1, R
L
= 100
, Unless Otherwise Specified (Continued)
PARAMETER
TEST CONDITIONS
TEMP (
o
C)
MIN
TYP
MAX
UNITS
GAIN
(A
CL
)
CONNECTIONS
+INPUT (PIN 3)
-INPUT (PIN 2)
-1
GND
Input
+1 (Note)
Input
NC (Floating)
+2
Input
GND
NOTE: Use HFA1112A For Maximum Stability.
HFA1112, HFA1112A
5
(as illustrated in the curves), the maximum bandwidth is
obtained without sacrificing stability. Even so, bandwidth
does decrease as you move to the right along the curve.
For example, at A
V
= +1, R
S
= 50
, C
L
= 30pF, the overall
bandwidth is limited to 300MHz, and bandwidth drops to
100MHz at A
V
= +1, R
S
= 5
, C
L
= 340pF.
Evaluation Board
The performance of the HFA1112 may be evaluated using
the HFA11XX Evaluation Board, slightly modified as follows:
1. Remove the 500
feedback resistor (R
2
), and leave the
connection open.
2. a. For A
V
= +1 evaluation, remove the 500
gain setting
resistor (R
1
), and leave pin 2 floating.
b. For A
V
= +2, replace the 500
gain setting resistor with
a 0
resistor to GND.
The layout and modified schematic of the board are shown
in Figure 2.
To order evaluation boards (part number HFA11XXEVAL),
please contact your local sales office.
R
S
(
)
LOAD CAPACITANCE (pF)
50
45
40
35
30
25
20
15
10
5
0
0
40
80
120
160
200
240
280
320
360
400
A
V
= +1
A
V
= +2
FIGURE 1. RECOMMENDED SERIES OUTPUT RESISTOR vs
LOAD CAPACITANCE
1
2
3
4
8
7
6
5
+5V
10
F
0.1
F
V
H
50
GND
GND
R
1
-5V
0.1
F
10
F
50
IN
OUT
V
L
(A
V
= +1)
or 0
(A
V
= +2)
V
H
+IN
V
L
V+
GND
1
V-
OUT
TOP LAYOUT
BOTTOM LAYOUT
FIGURE 2. EVALUATION BOARD SCHEMATIC AND LAYOUT
HFA1112, HFA1112A
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