HFA1135IBZ96 Intersil, HFA1135IBZ96 Datasheet - Page 7

• Manufacturer Part Number: HFA1135IBZ96
• Description: IC OPAMP CFA 360MHZ LP 8-SOIC
• Manufacturer: Intersil

Specifications of HFA1135IBZ96

• Applications: Current Feedback
• Number Of Circuits: 1
• -3db Bandwidth: 360MHz
• Slew Rate: 1530 V/µs
• Current - Supply: 6.9mA
• Current - Output / Channel: 60mA
• Voltage - Supply, Single/dual (±): ±4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When the output is limited, the negative input continues to
source a slewing current (I
output to the quiescent voltage defined by the input. Q
must sink this current while limiting, because the -IN current
is always mirrored onto the high impedance node. The
limiting current is calculated as:
I
As an example, a unity gain circuit with V
would have I
for unity gain applications). Note that I
when the output is limited.
Limit Accuracy
The limited output voltage will not be exactly equal to the
voltage applied to V
mismatches, necessitate a limit accuracy parameter which is
found in the device specifications. Limit accuracy is a
function of the limiting conditions. Referring again to Figure
3, it can be seen that one component of limit accuracy is the
V
transistors. If the transistors always ran at the same current
level there would be no V
to the inaccuracy. The Q
constant current, but as described earlier, the current
through Q
increases, causing the limited output voltage to increase as
well. I
((A
the overdrive increases. For example, accuracy degrades
from +15mV to +70mV when the overdrive increases from
100% to 200% (A
Consideration must also be given to the fact that the limit
voltages have an effect on amplifier linearity. The “Linearity
Near Limit Voltage” curves, Figures 34 and 35, illustrate the
impact of several limit levels on linearity.
Limit Range
Unlike some competitor devices, both V
ranges that cross 0V. While V
V
restrictions indicated in the specifications. For example, the
HFA1135 could be limited to ECL output levels by setting
V
the same voltage (GND for instance) but the result won’t be a
DC output voltage from an AC input signal. A 150mV - 200mV
AC signal will still be present at the output.
Recovery from Overdrive
The output voltage remains at the limit level as long as the
overdrive condition remains. When the input voltage drops
below the overdrive level (V
linear operation. A time delay, known as the Overdrive
Recovery Time, is required for this resumption of linear
operation. Overdrive recovery time is defined as the
difference between the amplifier’s propagation delay exiting
LIMIT
L
H
BE
, both may be positive or negative, within the range
V
= -0.8V and V
mismatch between the Q
x V
LIMIT
= (V
IN
X5
-IN
- V
is a function of the overdrive level
LIMIT
is equivalent to I
LIMIT
- V
OUT LIMITED
L
V
= (2V - 1V)/1.5kΩ + 2V/∞ = 667µA (R
= -1.8V. V
) / V
H
= +2, V
or V
LIMIT
X6
BE
L
LIMIT
. Offset errors, mostly due to VBE
H
transistors are biased at a
LIMIT
), so limit accuracy degrades as
H
mismatch, and no contribution
= 500mV, R
H
LIMIT
X6
7
)/R
and V
must be more positive than
) in an attempt to force the
/A
transistors, and the Q
F
. V
V
+ V
) the amplifier returns to
CC
L
BE
may be connected to
-IN
H
IN
increases by I
increases as I
F
and V
/R
= 2V, and V
= 250Ω).
G
.
L
have usable
H
LIMIT
G
P5
LIMIT
X5
= 1V,
= ∞
HFA1135
limiting and the amplifier’s normal propagation delay, and it is
a strong function of the overdrive level. Figure 36 details the
overdrive recovery time for various limit and overdrive levels.
Benefits of Output Limiting
The plots of “Pulse Response Without Limiting” and “Pulse
Response With Limiting” (Figures 4 and 5) highlight the
advantages of output limiting. Besides the obvious benefit of
constraining the output swing to a defined range, limiting the
output excursions also keeps the output transistors from
saturating, which prevents unwanted saturation artifacts
from distorting the output signal. Output limiting also takes
advantage of the HFA1135’s ultra-fast overdrive recovery
time, reducing the recovery time from 2.3ns to 0.3ns, based
on the amplifier’s normal propagation delay of 1.2ns.
-0.5
-1.0
2.0
1.5
1.0
0.5
-0.5
-1.0
2.0
1.5
1.0
0.5
0
0
FIGURE 4. PULSE RESPONSE WITHOUT LIMITING
FIGURE 5. PULSE RESPONSE WITH LIMITING
V
A
A
IN
V
V
H
= +2, R
= +2, R
= +2.0V, V
OUT
F
F
IN
= 250Ω
= 250Ω
L
= 0V
TIME (5ns/DIV.)
OUT
TIME (5ns/DIV.)
4.0
3.0
2.0
1.0
0
-1.0
-2.0
2.0
1.0
0
-1.0