ISL55210IRTZ Intersil, ISL55210IRTZ Datasheet - Page 12

• Manufacturer Part Number: ISL55210IRTZ
• Description: IC OPAMP DIFF 2200MHZ LP 16TQFN
• Manufacturer: Intersil

Specifications of ISL55210IRTZ

• Amplifier Type: Differential
• Number Of Circuits: 1
• Slew Rate: 150 V/µs
• Gain Bandwidth Product: 4GHz
• Current - Input Bias: 50µA
• Voltage - Input Offset: 100µV
• Current - Supply: 35mA
• Current - Output / Channel: 45mA
• Voltage - Supply, Single/dual (±): 3 V ~ 4.2 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• -3db Bandwidth: -

For instance, if a minimum noise configuration is not required,
but it is desirable to increase the feedback resistors to reduce the
added loading they present to the output stage, the R
resistors can be scaled up to achieve the same gain with an
additional termination resistance added across the input
transformer to adjust the termination impedance. Figure 31
shows an example using a 1:2 input turns ratio where the R
R
resistance added. This example provides a single to differential
signal gain of 20dB and input impedance of 50Ω to the source.
The 1:2 turn ratio transformer needs a 200Ω differential
secondary impedance to provide an input side 50Ω match. This is
provided here by the parallel combination of the 2Ω - 200Ω R
resistors and the 400Ω parallel impedance at the transformer
secondary.
This circuit has scaled the feedback resistor up to 1kΩ to still
achieve the amplifier gain of 5V/V which gives the overall gain of
10V/V (20dB) when the 1:2 step up at the input is considered.
The particular transformer shown is typical of 1:2 turns ratio
broadband transformers, but there a many alternates with the
similar or improved characteristics.
This input interface also simplifies the input common mode
control. The V
In most DC coupled FDA applications, the input common mode
voltage is determined by both this output common mode and the
source signal. In a configuration like Figure 31, there is no path
for a common mode current to flow from output to input, so the
input common mode voltage equals the output. A similar effect
could be achieved with just two blocking caps on the two R
resistors. A DC coupled, single to differential, configuration will
also have a common mode input that is moving with the input
signal. Converting to just a differential signal at the amplifier, as
in Figure 31, removes any input signal related artifacts from the
input common mode making the ISL55210 behave as a
differential only VFA amplifier. There is only a very small
differential error signal at the inputs set by the loop gain, as in a
normal single ended VFA application, but no common mode
signal related terms.
F
FIGURE 31. SINGLE TO DIFFERENTIAL WITH REDUCED FEEDBACK
elements have been scaled up and a shunt termination
V
50
i
1µF
ADT4-
1:2
1WT
CM
LOADING
400
pin controls the output common mode voltage.
200
200
R
R
G
G
V
12
CM
1k
1k
R
R
F
F
+
-
+3.3V
ISL55210
G
and R
ISL55210
G
G
V
O
and
G
F
The examples shown are using the transformer to convert from
single to differential. However, if the source is already
differential, these same transformer input circuits can drive the
transformer differentially still providing impedance scaling if
needed and common mode rejection for both DC and AC
common mode issues. A good example would be differential
mixer outputs or SAW filter outputs. Those differential sources
could also be connected into the ISL55210 R
blocking caps as well eliminating the input transformer. The AC
termination impedance for the differential source will then be
the sum of the two R
used.
Amplifier I/O Range Limits
The ISL55210 is intended principally to give the lowest IM3
performance on the lowest power for a differential I/O
application. The amplifier will work DC coupled and over a
relatively wide supply range of 3.0V to 4.2V supplies. The outputs
have both a differential and common mode operating range
while the input pins have a common operating range. For single
supply operation, the ground pins are at ground as is the exposed
metal pad on the underside of the package. The ISL55210 can
operate split supply where then the ground pins will be a
negative supply voltage and the exposed metal pad is either
connected to this negative supply or left unconnected on an
insulating board layer.
Briefly, the I/O and V
The output swing limits are often asymmetrical around the V
voltage. The maximum single ended swings are set by these two
limits:
V
instance on a single 3.3V supply with the default V
1.2V, these two limits give the same result and the output pins
can swing down to 0.3V above -V
is raised to 1.5V, then the minimum output voltage will become
1.5V - 0.9V = 0.6V.
V
V
default 1.2V V
ground output pin voltages can be 3.3V - 1.5V = +1.8V or 0.6V
above the default V
Using these default conditions, and the maximum positive
excursion of 0.6V above the 1.2V output V
maximum differential V
ended limit or 2.4V
becomes the 0.9V below V
differential V
get this maximum output swing, increase the supply voltage until
+V
instance, then 1.3V + 0.9V + 1.5V = 3.7V will give an unclipped
1. Maximum V
2. Input common mode operating range of -V
3. Output V
4. Output V
OMIN
OMAX
OMAX
S
output V
output V
- 1.5V > V
is either -V
is set by a headroom limit to the positive supply to be:
= +V
S
CM
CM
O
O
P-P
- 1.5V. Again, on a 3.3V single supply and the
CM
CM
minimum (on each side) is either -V
maximum (on each side) is +V
CM
+ 0.5V
- 0.9V
is then 4X 0.9V to 3.6V
S
+ 0.9V. If we assume a V
setting, this mean the maximum referenced to
+ 0.3V or V
P-P
CM
setting = -V
CM
G
. Where +V
resistors when simple blocking caps are
voltage.
P-P
limits are:
CM
swing will be 4X this 0.6V single
, but then the absolute maximum
CM
S
+ 2V
S
S
- 0.9V whichever is less. So for
= 0V. If, however, the V
is increased the limit then
P-P
CM
CM
. So, for instance, to
G
S
setting, the
voltage of 1.3V for
S
- 1.5V
resistors through
+ 1.1V or the
S
CM
+ 0.3V or
March 2, 2011
voltage of
CM
FN7811.0
CM
pin