Datasheet

MAX4265–MAX4270
Ultra-Low-Distortion, +5V,
400MHz Op Amps with Disable
______________________________________________________________________________________ 15
5
-5
0.1M 1M 10M 100M 1G
-3
FREQUENCY (Hz)
GAIN (dB)
-1
1
3
2
0
-2
-4
4
C
L
= 10pF
R
ISO
= 12Ω
C
L
= 10pF
R
ISO
= 15Ω
C
L
= 10pF
R
ISO
= 18Ω
Figure 4b. MAX4269 Small-Signal Gain vs. Frequency With
Isolation Resistor
4
-6
0.1M 1M 10M 100M 1G
-4
FREQUENCY (Hz)
GAIN (dB)
-2
0
2
1
-1
-3
-5
3
C
L
= 22pF
R
ISO
= 22Ω
C
L
= 22pF
R
ISO
= 3.9Ω
C
L
= 22pF
R
ISO
= 6Ω
Figure 4c. MAX4270 Small-Signal Gain vs. Frequency With
Isolation Resistor
Power Supplies, Bypassing, and Layout
The MAX4265–MAX4270 operate from a single +4.5V
to +8.0V supply or in a dual-supply configuration.
When operating with a single supply, connect the V
EE
pins directly to the ground plane. Bypass V
CC
to
ground with ceramic chip capacitors. Due to the
MAX4265–MAX4270s’ wide bandwidth, use a 1nF
capacitor in parallel with a 0.1µF to 1µF capacitor. If the
device is located more than 10cm from the power sup-
ply, adding a larger bulk capacitor will improve perfor-
mance.
When operating with dual supplies, ensure that the total
voltage across the device (V
CC
to V
EE
) does not
exceed +8V. Therefore, supplies of ±2.5V, ±3.3V, and
asymmetrical supplies are possible. For example, oper-
ation with V
CC
= +5V and V
EE
= -3V provides sufficient
voltage swing for the negative pulses found in video
signals. When operating with dual supplies, the V
CC
pins and the V
EE
pins should be bypassed using the
same guidelines stated in the paragraph above.
Because the MAX4265–MAX4270 have high band-
width, circuit layout becomes critical. A solid ground
plane provides a low-inductance path for high-speed
transient currents. Use multiple vias to the ground
plane for each bypass capacitor. If V
EE
is connected to
ground, use multiple vias here, too. Avoid sharing
ground vias with other signals to reduce crosstalk
between circuit sections.
Avoid stray capacitance at the op amp’s inverting
inputs. Stray capacitance, in conjunction with the feed-
back resistance, forms an additional pole in the cir-
cuit’s transfer function, with its associate phase shift.
Minimizing the trace lengths connected to the inverting
input helps minimize stray capacitance.
Chip Information
MAX4265/66/67 TRANSISTOR COUNT: 132
MAX4268/69/70 TRANSISTOR COUNT: 285
PROCESS: Bipolar