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.
θ
JA
is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
PARAMETER
INPUT CHARACTERISTICS
Input Offset Voltage
V
SUPPLY
=
±5V,
A
V
= +1, R
F
= 510Ω, C
COMP
= 0pF, R
L
= 100Ω , Unless Otherwise Specified
TEST CONDITIONS
(NOTE 3)
TEST LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
A
A
25
Full
Full
25
85
-40
25
85
-40
25
Full
Full
25
85
-40
25
85
-40
25
Full
Full
25
85
-40
25
85
-40
-
-
-
47
45
45
50
47
47
-
-
-
-
-
-
0.8
0.5
0.5
-
-
-
-
-
-
-
-
-
2
3
1
50
48
48
54
50
50
6
10
5
0.5
0.8
0.8
1.2
0.8
0.8
2
5
60
3
4
4
2
4
4
5
8
10
-
-
-
-
-
-
15
25
60
1
3
3
-
-
-
7.5
15
200
6
8
8
5
8
8
mV
mV
µV/
o
C
dB
dB
dB
dB
dB
dB
µA
µA
nA/
o
C
µA/V
µA/V
µA/V
MΩ
MΩ
MΩ
µA
µA
nA/
o
C
µA/V
µA/V
µA/V
µA/V
µA/V
µA/V
Average Input Offset Voltage Drift
Input Offset Voltage Common-Mode
Rejection Ratio
∆V
CM
=
±1.8V
∆V
CM
=
±1.8V
∆V
CM
=
±1.2V
Input Offset Voltage Power Supply
Rejection Ratio
∆V
PS
=
±1.8V
∆V
PS
=
±1.8V
∆V
PS
=
±1.2V
Non-Inverting Input Bias Current
B
A
A
A
A
A
A
A
A
Non-Inverting Input Bias Current Drift
Non-Inverting Input Bias Current
Power Supply Sensitivity
∆V
PS
=
±1.8V
∆V
PS
=
±1.8V
∆V
PS
=
±1.2V
Non-Inverting Input Resistance
∆V
CM
=
±1.8V
∆V
CM
=
±1.8V
∆V
CM
=
±1.2V
Inverting Input Bias Current
B
A
A
A
A
A
A
A
A
Inverting Input Bias Current Drift
Inverting Input Bias Current
Common-Mode Sensitivity
∆V
CM
=
±1.8V
∆V
CM
=
±1.8V
∆V
CM
=
±1.2V
Inverting Input Bias Current Power
Supply Sensitivity
∆V
PS
=
±1.8V
∆V
PS
=
±1.8V
∆V
PS
=
±1.2V
B
A
A
A
A
A
A
3-29
HFA1106
Electrical Specifications
PARAMETER
Inverting Input Resistance
Input Capacitance
Input Voltage Common Mode Range
(Implied by V
IO
CMRR, +R
IN
, and -I
BIAS
CMS Tests)
Input Noise Voltage Density
f = 100kHz
V
SUPPLY
=
±5V,
A
V
= +1, R
F
= 510Ω, C
COMP
= 0pF, R
L
= 100Ω , Unless Otherwise Specified
(Contin-
TEST CONDITIONS
(NOTE 3)
TEST LEVEL
C
C
A
A
B
B
B
TEMP.
(
o
C)
25
25
25, 85
-40
25
25
25
MIN
-
-
±1.8
±1.2
-
-
-
TYP
60
1.6
±2.4
±1.7
3.5
2.5
20
MAX
-
-
-
-
-
-
-
UNITS
Ω
pF
V
V
nV/√Hz
pA/√Hz
pA/√Hz
Non-Inverting Input Noise Current Density f = 100kHz
Inverting Input Noise Current Density
TRANSFER CHARACTERISTICS
Open Loop Transimpedance Gain
AC CHARACTERISTICS
A
V
= -1
f = 100kHz
C
25
-
500
-
kΩ
A
V
= +2, R
F
= 100Ω, R
COMP
= 51Ω, Unless Otherwise Specified
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
B
B
B
B
B
B
B
B
B
B
B
B
A
25
25
25
25
25
25
25
25
25
25
25
25
Full
250
140
65
185
110
55
45
25
13
60
15
11
1
315
170
80
245
140
70
65
40
17
100
30
14
-
-
-
-
-
-
-
-
-
-
-
-
-
-
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
V/V
-3dB Bandwidth
(A
V
= +1, R
F
= 150Ω, V
OUT
= 0.2V
P-P
)
-3dB Bandwidth
(A
V
= +2, V
OUT
= 0.2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
±0.1dB
Flat Bandwidth
(A
V
= +1, R
F
= 150Ω, V
OUT
= 0.2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
±0.1dB
Flat Bandwidth
(A
V
= +2, V
OUT
= 0.2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
Minimum Stable Gain
OUTPUT CHARACTERISTICS
Output Voltage Swing
A
V
= +2, R
F
= 100Ω, R
COMP
= 51Ω, Unless Otherwise Specified
A
V
= -1, R
F
= 510Ω
A
A
25
Full
25, 85
-40
25
25
25
25
25
25
25
25
25
25
25
25
25
25
±3
±2.8
50
28
-
-
-45
-42
-38
-50
-48
-48
-42
-38
-34
-46
-52
-50
±3.4
±3
60
42
0.07
90
-53
-48
-44
-57
-56
-56
-46
-42
-38
-57
-57
-57
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
V
V
mA
mA
Ω
mA
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
Output Current
A
V
= -1, R
L
= 50Ω,
R
F
= 510Ω
DC
A
V
= -1
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
A
A
B
B
B
B
B
B
B
B
B
B
B
B
B
B
Closed Loop Output Impedance
Output Short Circuit Current
Second Harmonic Distortion
(10MHz, V
OUT
= 2V
P-P
)
Third Harmonic Distortion
(10MHz, V
OUT
= 2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
Second Harmonic Distortion
(20MHz, V
OUT
= 2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
Third Harmonic Distortion
(20MHz, V
OUT
= 2V
P-P
)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
3-30
HFA1106
Electrical Specifications
PARAMETER
TRANSIENT CHARACTERISTICS
V
SUPPLY
=
±5V,
A
V
= +1, R
F
= 510Ω, C
COMP
= 0pF, R
L
= 100Ω , Unless Otherwise Specified
(Contin-
TEST CONDITIONS
(NOTE 3)
TEST LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
A
V
= +2, R
F
= 100Ω, R
COMP
= 51Ω
,
Unless Otherwise Specified
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
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
-
-
-
-
-
-
-
-
-
-
-
-
580
400
470
300
320
200
750
500
550
350
380
250
-
-
-
-
2.6
3.7
5.2
2.7
3.9
5.9
1.5
6
4
2
6.5
2.5
680
545
530
410
365
300
910
720
730
520
485
375
26
33
49
8.5
2.9
4.2
6.2
3.2
4.4
6.9
4
10
7.5
5
12
7.5
-
-
-
-
-
-
-
-
-
-
-
-
35
43
75
-
ns
ns
ns
ns
ns
ns
%
%
%
%
%
%
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
V/µs
ns
ns
ns
ns
Rise and Fall Times
(V
OUT
= 0.5V
P-P
, A
V
= +1, R
F
= 150Ω)
Rise and Fall Times
(V
OUT
= 0.5V
P-P
, A
V
= +2)
C
C
= 0pF
C
C
= 2pF
C
C
= 5pF
Overshoot (Note 4)
V
OUT
= 250mV
P-P
(A
V
= +1, R
F
= 150Ω, V
IN
t
RISE
= 2.5ns)
V
OUT
= 2V
P-P
V
OUT
= 0V to 2V
Overshoot (Note 4)
(A
V
= +2, V
IN
t
RISE
= 2.5ns)
V
OUT
= 250mV
P-P
V
OUT
= 2V
P-P
V
OUT
= 0V to 2V
Slew Rate
(V
OUT
= 4V
P-P
, A
V
= +1, R
F
= 150Ω)
+SR, C
C
= 0pF
-SR, C
C
= 0pF
+SR, C
C
= 2pF
-SR, C
C
= 2pF
+SR, C
C
= 5pF
-SR, C
C
= 5pF
Slew Rate
(V
OUT
= 5V
P-P
, A
V
= +2)
+SR, C
C
= 0pF
-SR, C
C
= 0pF
+SR, C
C
= 2pF
-SR, C
C
= 2pF
+SR, C
C
= 5pF
-SR, C
C
= 5pF
Settling Time
(V
OUT
= +2V to 0V Step,
C
C
= 0pF to 5pF)
Overdrive Recovery Time
To 0.1%
To 0.05%
To 0.02%
V
IN
=
±2V
VIDEO CHARACTERISTICS
A
V
= +2, R
F
= 100Ω, R
COMP
= 51Ω, Unless Otherwise Specified
Differential Gain
(f = 3.58MHz, R
L
= 150Ω)
Differential Phase
(f = 3.58MHz, R
L
= 150Ω)
POWER SUPPLY CHARACTERISTICS
Power Supply Range
Power Supply Current
C
A
A
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. 2V
P-P
) yielding a higher overshoot limit compared to the V
OUT
= 0V to
2V condition.
25
25
Full
±4.5
-
-
-
5.8
5.9
±5.5
6.1
6.3
V
mA
mA
C
C
= 0pF
C
C
= 5pF
C
C
= 0pF
C
C
= 5pF
B
B
B
B
25
25
25
25
-
-
-
-
0.02
0.02
0.05
0.07
-
-
-
-
%
%
Degrees
Degrees
3-31
HFA1106
Application Information
Optimum Feedback Resistor
All current feedback amplifiers (CFAs) require a feedback
resistor (R
F
) 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
HFA1106 design is optimized for R
F
= 150Ω at a gain of +1.
Decreasing R
F
decreases stability resulting in excessive
peaking and overshoot - Note: Capacitive feedback causes
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 (e.g., R
F
= 100Ω for
A
V
= +2).
Why Use Externally Compensated Amplifiers?
Externally compensated op amps were originally developed
to allow operation at gains below the amplifier’s minimum
stable gain. This enabled development of non-unity gain sta-
ble op amps with very high bandwidth and slew rates. Users
needing lower closed loop gains could stabilize the amplifier
with external compensation if the associated performance
decrease was tolerable.
With the advent of CFAs, unity gain stability and high perfor-
mance are no longer mutually exclusive, so why offer unity
gain stable op amps with compensation pins?
The main reason for external compensation is to allow users
to tailor the amplifier’s performance to their specific system
needs. Bandwidth can be limited to the exact value required,
thereby eliminating excess bandwidth and its associated
noise. A compensated op amp is also more predictable;
lower lot-to-lot variation requires less system overdesign to
cover process variability. Finally, access to the internal high
impedance node allows users to implement external output
limiting or allows for stabilizing the amplifier when driving
large capacitive loads.
Noise Advantages - Uncompensated
The HFA1106 delivers lower broadband noise even without
an external compensation capacitor. Package capacitance
present at the Comp pin stabilizes the op amp, so lower
value feedback resistors can be used. A smaller value R
F
minimizes the noise voltage contribution of the amplifier’s
inverting input noise current - I
NI
x R
F
, usually a large con-
tributor on CFAs - and minimizes the resistor’s thermal noise
contribution (4KTR
F
). Figure 1 details the HFA1105 broad-
band noise performance in its recommended configuration
of A
V
= +2, and R
F
= 510Ω. Adding a Comp pin to the
HFA1105 (thereby creating the HFA1106) yields the 23%
noise reduction shown in Figure 2. In both cases, the scope
bandwidth, 100MHz, limits the measurement range to pre-
vent amplifier bandwidth differences from affecting the
results.
E
N
= 350µ V
RMS
E
N
= 456µ V
RMS
FIGURE 1. HFA1105 NOISE PERFORMANCE, A
V
= +2,
R
F
= 510Ω
FIGURE 2. HFA1106 NOISE PERFORMANCE,
UNCOMPENSATED, A
V
= +2, R
F
= 100Ω
Offset Advantage
An added advantage of the lower value R
F
is a smaller DC
output offset. The op amp’s inverting input bias current (I
BI
)
flows through the feedback resistor and generates an offset
voltage error defined by:
V
E
=
I
BI
x R
F
;
and V
OS
=
A
V
( ±
V
IO
) ±
V
E
Reducing R
F
reduces these errors.
Bandwidth Limiting
The HFA1106 bandwidth may be limited by connecting a
resistor, R
COMP
(required to damp the interaction between
the compensation capacitor and the package parasitics),
and capacitor, C
COMP
, in series from pin 8 to GND. Typical
performance characteristics for various C
COMP
values are
listed in the specification table. The HFA1106 is already
unity gain stable, so the main reason for limiting the band-
width is to reduce the broadband noise.
Noise Advantages - Compensated
System noise reduction is maximized by limiting the op amp to
the bandwidth required for the application. Noise increases as
the square root of the bandwidth increase (4x bandwidth
increase yields 2x noise increase), so eliminating excess
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