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.
θ
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
= 100Ω, Unless Otherwise Specified
PARAMETER
INPUT CHARACTERISTICS
Output Offset Voltage
25
Full
Output Offset Voltage Drift
PSRR
Full
25
Full
Input Noise Voltage (Note 3)
Non-Inverting Input Noise Current (Note 3)
Non-Inverting Input Bias Current
100kHz
100kHz
25
25
25
Full
Non-Inverting Input Resistance
Inverting Input Resistance (Note 2)
Input Capacitance
Input Common Mode Range
TRANSFER CHARACTERISTICS
Gain
A
V
= +1, V
IN
= +2V
A
V
= +2, V
IN
= +1V
A
V
= +2,
±2V
Full Scale
A
V
= -1
R
L
= 50Ω
DC, A
V
= +2
25
Full
Gain
25
Full
DC Non-Linearity (Note 3)
OUTPUT CHARACTERISTICS
Output Voltage (Note 3)
25
Full
Output Current (Note 3)
25, 85
-40
Closed Loop Output Impedance
POWER SUPPLY CHARACTERISTICS
Supply Voltage Range
Supply Current (Note 3)
Full
25
Full
AC CHARACTERISTICS
-3dB Bandwidth
(V
OUT
= 0.2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
25
25
25
450
500
350
800
850
550
-
-
-
MHz
MHz
MHz
±4.5
-
-
-
21
-
±5.5
26
33
V
mA
mA
25
±3.0
±2.5
50
35
-
±3.3
±3.0
60
50
0.3
-
-
-
-
-
V
V
mA
mA
Ω
25
0.980
0.975
1.96
1.95
-
0.990
-
1.98
-
0.02
1.02
1.025
2.04
2.05
-
V/V
V/V
V/V
V/V
%
25
25
25
Full
-
-
-
39
35
-
-
-
-
25
240
-
±2.5
8
-
10
45
-
9
37
25
-
50
300
2
±2.8
25
35
-
-
-
-
-
40
65
-
360
-
-
mV
mV
µV/
o
C
dB
dB
nV/√Hz
pA/√Hz
µA
µA
kΩ
Ω
pF
V
TEST CONDITIONS
TEMP (
o
C)
MIN
TYP
MAX
UNITS
2
HFA1112
Electrical Specifications
V
SUPPLY
=
±5V,
A
V
= +1, R
L
= 100Ω, Unless Otherwise Specified
(Continued)
PARAMETER
Slew Rate
(V
OUT
= 5V
P-P
, Note 2)
TEST CONDITIONS
A
V
= -1
A
V
= +1
A
V
= +2
Full Power Bandwidth
(V
OUT
= 5V
P-P
, Note 3)
A
V
= -1
A
V
= +1
A
V
= +2
Gain Flatness
(to 30MHz, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
Gain Flatness
(to 50MHz, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
Gain Flatness
(to 100MHz, Notes 2, 3)
Linear Phase Deviation
(to 100MHz, Note 3)
A
V
= -1
A
V
= +2
A
V
= -1
A
V
= +1
A
V
= +2
2nd Harmonic Distortion
(30MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
3rd Harmonic Distortion
(30MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
2nd Harmonic Distortion
(50MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
3rd Harmonic Distortion
(50MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
2nd Harmonic Distortion
(100MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
3rd Harmonic Distortion
(100MHz, V
OUT
= 2V
P-P
, Notes 2, 3)
A
V
= -1
A
V
= +1
A
V
= +2
3rd Order Intercept
(A
V
= +2, Note 3)
1dB Compression
(A
V
= +2, Note 3)
Reverse Isolation
(S
12
, Note 3)
100MHz
300MHz
100MHz
300MHz
40MHz
100MHz
600MHz
TRANSIENT CHARACTERISTICS
Rise Time
(V
OUT
= 0.5V Step, Note 2)
A
V
= -1
A
V
= +1
A
V
= +2
25
25
25
-
-
-
500
480
700
800
750
1000
ps
ps
ps
TEMP (
o
C)
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
MIN
1500
800
1100
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
TYP
2400
1500
1900
300
150
220
±0.02
±0.1
±0.015
±0.05
±0.2
±0.036
±0.10
±0.07
±0.13
±0.83
±0.05
-52
-57
-52
-71
-73
-72
-47
-53
-47
-63
-68
-65
-41
-50
-42
-55
-49
-62
28
13
19
12
-70
-60
-32
MAX
-
-
-
-
-
-
-
-
±0.04
-
-
±0.08
-
±0.22
-
-
-
-
-
-45
-
-
-65
-
-
-40
-
-
-55
-
-
-35
-
-
-45
-
-
-
-
-
-
-
UNITS
V/µs
V/µs
V/µs
MHz
MHz
MHz
dB
dB
dB
dB
dB
dB
dB
dB
Degrees
Degrees
Degrees
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBm
dBm
dBm
dBm
dB
dB
dB
3
HFA1112
Electrical Specifications
V
SUPPLY
=
±5V,
A
V
= +1, R
L
= 100Ω, Unless Otherwise Specified
(Continued)
PARAMETER
Rise Time
(V
OUT
= 2V Step)
TEST CONDITIONS
A
V
= -1
A
V
= +1
A
V
= +2
Overshoot
(V
OUT
= 0.5V Step, Input t
R
/t
F
= 200ps,
Notes 2, 3, 4)
0.1% Settling Time (Note 3)
0.05% Settling Time
Overdrive Recovery Time
Differential Gain
A
V
= -1
A
V
= +1
A
V
= +2
V
OUT
= 2V to 0V
V
OUT
= 2V to 0V
V
IN
= 5V
P-P
A
V
= +1, 3.58MHz, R
L
= 150Ω
A
V
= +2, 3.58MHz, R
L
= 150Ω
Differential Phase
A
V
= +1, 3.58MHz, R
L
= 150Ω
A
V
= +2, 3.58MHz, R
L
= 150Ω
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.
TEMP (
o
C)
25
25
25
25
25
25
25
25
25
25
25
25
25
MIN
-
-
-
-
-
-
-
-
-
-
-
-
-
TYP
0.82
1.06
1.00
12
45
6
11
15
8.5
0.03
0.02
0.05
0.04
MAX
-
-
-
30
65
20
-
-
-
-
-
-
-
UNITS
ns
ns
ns
%
%
%
ns
ns
ns
%
%
Degrees
Degrees
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:
GAIN
(A
CL
)
-1
+1
+2
CONNECTIONS
+INPUT (PIN 3)
GND
Input
Input
-INPUT (PIN 2)
Input
NC (Floating)
GND
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
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 (10µF) tantalum in parallel with a small value
(0.1µF) chip capacitor works well in most cases.
4
HFA1112
(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
= 50Ω, C
L
= 30pF, the overall
bandwidth is limited to 300MHz, and bandwidth drops to
100MHz at A
V
= +1, R
S
= 5Ω, 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 500Ω feedback resistor (R
2
), and leave the
connection open.
2. a. For A
V
= +1 evaluation, remove the 500Ω gain setting
resistor (R
1
), and leave pin 2 floating.
b. For A
V
= +2, replace the 500Ω gain setting resistor with
a 0Ω resistor to GND.
50
45
40
35
30
25
20
15
10
5
0
0
A
V
= +1
The layout and modified schematic of the board are shown in
Figure 2.
To order evaluation boards (part number HFA11XXEVAL),
