1
HFA1105
330MHz, Low Power, Current Feedback
Video Operational Amplifier
The HFA1105 is a high speed, low power current feedback
amplifier built with Intersil's proprietary complementary
bipolar UHF-1 process.
This amplifier features an excellent combination of low
power dissipation (58mW) and high performance. The slew
rate, bandwidth, and low output impedance (0.08
) make
this amplifier a good choice for driving Flash ADCs.
Component and composite video systems also benefit from
this op amp's excellent gain flatness, and good differential
gain and phase specifications. The HFA1105 is ideal for
interfacing to Intersil's line of video crosspoint switches
(HA4201, HA4600, HA4314, HA4404, HA4344), to create
high performance, low power switchers and routers.
The HFA1105 is a low power, high performance upgrade for
the CLC406. For a comparable amplifier with output disable
or output limiting functions, please see the data sheets for
the HFA1145 and HFA1135 respectively.
For Military grade product, please refer to the HFA1145/883
data sheet
.
Ordering Information
NOTE: Requires a SOIC-to-DIP adapter. See "Evaluation Board"
section inside.
Features
Low Supply Current . . . . . . . . . . . . . . . . . . . . . . . . 5.8mA
High Input Impedance . . . . . . . . . . . . . . . . . . . . . . . 1M
Wide -3dB Bandwidth. . . . . . . . . . . . . . . . . . . . . . 330MHz
Very Fast Slew Rate . . . . . . . . . . . . . . . . . . . . . 1000V/
s
Gain Flatness (to 75MHz) . . . . . . . . . . . . . . . . . . . 0.1dB
Differential Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.02%
Differential Phase. . . . . . . . . . . . . . . . . . . . . 0.03 Degrees
Pin Compatible Upgrade for CLC406
Applications
Flash A/D Drivers
Video Switching and Routing
Professional Video Processing
Video Digitizing Boards/Systems
Multimedia Systems
RGB Preamps
Medical Imaging
Hand Held and Miniaturized RF Equipment
Battery Powered Communications
Pinout
HFA1105 (SOIC)
TOP VIEW
PART NUMBER
(BRAND)
TEMP. RANGE
(
o
C)
PACKAGE
PKG.
DWG. #
HFA1105IB
(H1105I)
-40 to 85
8 Ld SOIC
M8.15
HFA11XXEVAL (Note) DIP Evaluation Board for High Speed
Op Amps
NC
-IN
+IN
V-
1
2
3
4
8
7
6
5
NC
V+
OUT
NC
-
+
Data Sheet
May 2003
FN3395.7
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2003. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
2
Absolute Maximum Ratings
Thermal Information
Supply Voltage (V+ to V-) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11V
DC Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
SUPPLY
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8V
Output Current (Note 1) . . . . . . . . . . . . . . . . .Short Circuit Protected
30mA Continuous
60mA
50% Duty Cycle
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>600V
Temperature Range. . . . . . . . . . . . . . . . . . . . . . . . . . -40
o
C to 85
o
C
Thermal Resistance (Typical, Note 2)
JA
(
o
C/W)
SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
165
Maximum Junction Temperature (Die). . . . . . . . . . . . . . . . . . . .175
o
C
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
(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.
NOTES:
1. Output is short circuit protected to ground. Brief short circuits to ground will not degrade reliability, however continuous (100% duty cycle) output
current must not exceed 30mA for maximum reliability.
2.
JA
is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
V
SUPPLY
= 5V, A
V
= +1, R
F
= 510W, R
L
= 100W, Unless Otherwise Specified
PARAMETER
TEST CONDITIONS
(NOTE 3)
TEST
LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
INPUT CHARACTERISTICS
Input Offset Voltage
A
25
-
2
5
mV
A
Full
-
3
8
mV
Average Input Offset Voltage Drift
B
Full
-
1
10
V/
o
C
Input Offset Voltage
Common-Mode Rejection Ratio
V
CM
=
1.8V
A
25
47
50
-
dB
V
CM
=
1.8V
A
85
45
48
-
dB
V
CM
=
1.2V
A
-40
45
48
-
dB
Input Offset Voltage
Power Supply Rejection Ratio
V
PS
=
1.8V
A
25
50
54
-
dB
V
PS
=
1.8V
A
85
47
50
-
dB
V
PS
=
1.2V
A
-40
47
50
-
dB
Non-Inverting Input Bias Current
A
25
-
6
15
A
A
Full
-
10
25
A
Non-Inverting Input Bias Current Drift
B
Full
-
5
60
nA/
o
C
Non-Inverting Input Bias Current
Power Supply Sensitivity
V
PS
=
1.8V
A
25
-
0.5
1
A/V
V
PS
=
1.8V
A
85
-
0.8
3
A/V
V
PS
=
1.2V
A
-40
-
0.8
3
A/V
Non-Inverting Input Resistance
V
CM
=
1.8V
A
25
0.8
1.2
-
M
V
CM
=
1.8V
A
85
0.5
0.8
-
M
V
CM
=
1.2V
A
-40
0.5
0.8
-
M
Inverting Input Bias Current
A
25
-
2
7.5
A
A
Full
-
5
15
A
Inverting Input Bias Current Drift
B
Full
-
60
200
nA/
o
C
Inverting Input Bias Current
Common-Mode Sensitivity
V
CM
=
1.8V
A
25
-
3
6
A/V
V
CM
=
1.8V
A
85
-
4
8
A/V
V
CM
=
1.2V
A
-40
-
4
8
A/V
Inverting Input Bias Current
Power Supply Sensitivity
V
PS
=
1.8V
A
25
-
2
5
A/V
V
PS
=
1.8V
A
85
-
4
8
A/V
V
PS
=
1.2V
A
-40
-
4
8
A/V
HFA1105
3
Inverting Input Resistance
C
25
-
60
-
Input Capacitance
C
25
-
1.6
-
pF
Input Voltage Common Mode Range
(Implied by V
IO
CMRR, +R
IN
, and -I
BIAS
CMS Tests)
A
25, 85
1.8
2.4
-
V
A
-40
1.2
1.7
-
V
Input Noise Voltage Density (Note 6)
f = 100kHz
B
25
-
3.5
-
nV/
Hz
Non-Inverting Input Noise Current Density (Note 6)
f = 100kHz
B
25
-
2.5
-
pA/
Hz
Inverting Input Noise Current Density (Note 6)
f = 100kHz
B
25
-
20
-
pA/
Hz
TRANSFER CHARACTERISTICS
Open Loop Transimpedance Gain
A
V
= -1
C
25
-
500
-
k
AC CHARACTERISTICS R
F
= 510
, Unless Otherwise Specified
-3dB Bandwidth
(V
OUT
= 0.2V
P-P
, Note 6)
A
V
= +1, +R
S
= 510
B
25
-
270
-
MHz
B
Full
-
240
-
MHz
A
V
= -1, R
F
= 425
B
25
-
300
-
MHz
A
V
= +2
B
25
-
330
-
MHz
B
Full
-
260
-
MHz
A
V
= +10, R
F
= 180
B
25
-
130
-
MHz
B
Full
-
90
-
MHz
Full Power Bandwidth
(V
OUT
= 5V
P-P
at A
V
= +2/-1,
4V
P-P
at A
V
= +1, Note 6)
A
V
= +1, +R
S
= 510
B
25
-
135
-
MHz
A
V
= -1
B
25
-
140
-
MHz
A
V
= +2
B
25
-
115
-
MHz
Gain Flatness
(A
V
= +2, V
OUT
= 0.2V
P-P
, Note 6)
To 25MHz
B
25
-
0.03
-
dB
B
Full
-
0.04
-
dB
To 75MHz
B
25
-
0.11
-
dB
B
Full
-
0.22
-
dB
Gain Flatness
(A
V
= +1, +R
S
= 510
, V
OUT
= 0.2V
P-P
, Note 6)
To 25MHz
B
25
-
0.03
-
dB
To 75MHz
B
25
-
0.09
-
dB
Minimum Stable gain
A
Full
-
1
-
V/V
OUTPUT CHARACTERISTICS A
V
= +2, R
F
= 510
,
Unless Otherwise Specified
Output Voltage Swing (Note 6)
A
V
= -1, R
L
= 100
A
25
3
3.4
-
V
A
Full
2.8
3
-
V
Output Current (Note 6)
A
V
= -1, R
L
= 50
A
25, 85
50
60
-
mA
A
-40
28
42
-
mA
Output Short Circuit Current
B
25
-
90
-
mA
Closed Loop Output Impedance (Note 6)
DC
B
25
-
0.08
-
W
Second Harmonic Distortion
(V
OUT
= 2V
P-P
, Note 6)
10MHz
B
25
-
-48
-
dBc
20MHz
B
25
-
-44
-
dBc
Third Harmonic Distortion
(V
OUT
= 2V
P-P
, Note 6)
10MHz
B
25
-
-50
-
dBc
20MHz
B
25
-
-45
-
dBc
Reverse Isolation (S
12
, Note 6)
30MHz
B
25
-
-55
-
dB
Electrical Specifications
V
SUPPLY
= 5V, A
V
= +1, R
F
= 510W, R
L
= 100W, Unless Otherwise Specified (Continued)
PARAMETER
TEST CONDITIONS
(NOTE 3)
TEST
LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
HFA1105
4
TRANSIENT CHARACTERISTICS A
V
= +2, R
F
= 510
, Unless Otherwise Specified
Rise and Fall Times
V
OUT
= 0.5V
P-P
B
25
-
1.1
-
ns
B
Full
-
1.4
-
ns
Overshoot (Note 4)
(V
OUT
= 0 to 0.5V, V
IN
t
RISE
= 1ns)
+OS
B
25
-
3
-
%
-OS
B
25
-
5
-
%
Overshoot (Note 4)
(V
OUT
= 0.5V
P-P
, V
IN
t
RISE
= 1ns)
+OS
B
25
-
3
-
%
-OS
B
25
-
11
-
%
Slew Rate
(V
OUT
= 4V
P-P
, A
V
= +1, +R
S
= 510
)
+SR
B
25
-
1000
-
V/
s
B
Full
-
975
-
V/
s
-SR (Note 5)
B
25
-
650
-
V/
s
B
Full
-
580
-
V/
s
Slew Rate
(V
OUT
= 5V
P-P
, A
V
= +2)
+SR
B
25
-
1400
-
V/
s
B
Full
-
1200
-
V/
s
-SR (Note 5)
B
25
-
800
-
V/
s
B
Full
-
700
-
V/
s
Slew Rate
(V
OUT
= 5V
P-P
, A
V
= -1)
+SR
B
25
-
2100
-
V/
s
B
Full
-
1900
-
V/
s
-SR (Note 5)
B
25
-
1000
-
V/
s
B
Full
-
900
-
V/
s
Settling Time
(V
OUT
= +2V to 0V step, Note 6)
To 0.1%
B
25
-
15
-
ns
To 0.05%
B
25
-
23
-
ns
To 0.02%
B
25
-
30
-
ns
Overdrive Recovery Time
V
IN
=
2V
B
25
-
8.5
-
ns
VIDEO CHARACTERISTICS A
V
= +2, R
F
= 510
,
Unless Otherwise Specified
Differential Gain
(f = 3.58MHz)
R
L
= 150
B
25
-
0.02
-
%
R
L
= 75
B
25
-
0.03
-
%
Differential Phase
(f = 3.58MHz)
R
L
= 150
B
25
-
0.03
-
Degrees
R
L
= 75
B
25
-
0.05
-
Degrees
POWER SUPPLY CHARACTERISTICS
Power Supply Range
C
25
4.5
-
5.5
V
Power Supply Current (Note 6)
A
25
-
5.8
6.1
mA
A
Full
-
5.9
6.3
mA
NOTES:
3. Test Level: A. Production Tested; B. Typical or Guaranteed Limit Based on Characterization; C. Design Typical for Information Only.
4. Undershoot dominates for output signal swings below GND (e.g., 0.5V
P-P
), yielding a higher overshoot limit compared to the V
OUT
= 0 to 0.5V
condition. See the "Application Information" section for details.
5. Slew rates are asymmetrical if the output swings below GND (e.g. a bipolar signal). Positive unipolar output signals have symmetric positive and
negative slew rates comparable to the +SR specification. See the "Application Information" section, and the pulse response graphs for details.
6. See Typical Performance Curves for more information.
Electrical Specifications
V
SUPPLY
= 5V, A
V
= +1, R
F
= 510W, R
L
= 100W, Unless Otherwise Specified (Continued)
PARAMETER
TEST CONDITIONS
(NOTE 3)
TEST
LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
HFA1105
5
Application Information
Optimum Feedback Resistor
Although a current feedback amplifier's bandwidth
dependency on closed loop gain isn't as severe as that of a
voltage feedback amplifier, there can be an appreciable
decrease in bandwidth at higher gains. This decrease may
be minimized by taking advantage of the current feedback
amplifier's unique relationship between bandwidth and R
F
.
All current feedback amplifiers require a feedback resistor,
even for unity gain applications, and R
F
, in conjunction with
the internal compensation capacitor, sets the dominant pole
of the frequency response. Thus, the amplifier's bandwidth is
inversely proportional to R
F
. The HFA1105 design is
optimized for R
F
= 510
at a gain of +2. Decreasing R
F
decreases stability, resulting in excessive peaking and
overshoot (Note: Capacitive feedback will cause the same
problems due to the feedback impedance decrease at higher
frequencies). At higher gains, however, the amplifier is more
stable so R
F
can be decreased in a trade-off of stability for
bandwidth.
The table below lists recommended R
F
values for various
gains, and the expected bandwidth. For a gain of +1, a
resistor (
+
R
S
) in series with +IN is required to reduce gain
peaking and increase stability.
Non-Inverting Input Source Impedance
For best operation, the DC source impedance seen by the
non-inverting input should be
50
.
This is especially
important in inverting gain configurations where the non-
inverting input would normally be connected directly to GND.
Pulse Undershoot and Asymmetrical Slew Rates
The HFA1105 utilizes a quasi-complementary output stage to
achieve high output current while minimizing quiescent supply
current. In this approach, a composite device replaces the
traditional PNP pulldown transistor. The composite device
switches modes after crossing 0V, resulting in added
distortion for signals swinging below ground, and an
increased undershoot on the negative portion of the output
waveform (See Figures 5, 8, and 11). This undershoot isn't
present for small bipolar signals, or large positive signals.
Another artifact of the composite device is asymmetrical slew
rates for output signals with a negative voltage component.
The slew rate degrades as the output signal crosses through
0V (See Figures 5, 8, and 11), resulting in a slower overall
negative slew rate. Positive only signals have symmetrical
slew rates as illustrated in the large signal positive pulse
response graphs (See Figures 4, 7, and 10).
PC Board Layout
The amplifier's frequency response depends greatly on the
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
device's input and output connections. Capacitance,
parasitic or planned, connected to the output must be
minimized, or isolated as discussed in the next section.
Care must also be taken to minimize the capacitance to
ground at the amplifier's inverting input (-IN), as this
capacitance causes gain peaking, pulse overshoot, and if
large enough, instability. To reduce this capacitance, the
designer should remove the ground plane under traces
connected to
-IN, and keep connections to -IN as short as possible.
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
270MHz (for A
V
= +1). By decreasing R
S
as C
L
increases (as
illustrated in the curves), the maximum bandwidth is obtained
without sacrificing stability. In spite of this, the bandwidth
decreases as the load capacitance increases. For example, at
A
V
= +1, R
S
= 62
, C
L
= 40pF, the overall bandwidth is
limited to 180MHz, and bandwidth drops to 75MHz at A
V
=
+1, R
S
= 8
, C
L
= 400pF.
GAIN
(A
CL
)
R
F
(
)
BANDWIDTH
(MHz)
-1
425
300
+1
510 (+R
S
= 510
)
270
+2
510
330
+5
200
300
+10
180
130
HFA1105
PDF 
ZIP