MAX4412/MAX4413
Low-Cost, Low-Power, Ultra-Small, 3V/5V, 500MHz
Single-Supply Op Amps with Rail-to-Rail Outputs
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ADC Input Buffer
Input buffer amplifiers can be a source of significant
errors in high-speed analog-to-digital converter (ADC)
applications. The input buffer is usually required to
rapidly charge and discharge the ADC’s input, which is
often capacitive (see
Output Capacitive Loading and
Stability
). In addition, since a high-speed ADC’s input
impedance often changes very rapidly during the con-
version cycle, measurement accuracy must be main-
tained using an amplifier with very low output
impedance at high frequencies. The combination of
high speed, fast slew rate, low noise, and a low and
stable distortion overload makes the MAX4412/
MAX4413 ideally suited for use as buffer amplifiers in
high-speed ADC applications.
Layout and Power-Supply Bypassing
These amplifiers operate from a single +2.7V to +5.5V
power supply. Bypass V
CC
to ground with a 0.1µF
capacitor as close to the pin as possible.
Maxim recommends using microstrip and stripline tech-
niques to obtain full bandwidth. Design the PC board
for a frequency greater than 1GHz to prevent amplifier
performance degradation due to board parasitics.
Avoid large parasitic capacitances at inputs and out-
puts. Whether or not a constant-impedance board is
used, observe the following guidelines:
• Do not use wire-wrap boards due to their high induc-
tance.
• Do not use IC sockets because of the increased par-
asitic capacitance and inductance.
• Use surface-mount instead of through-hole compo-
nents for better high-frequency performance.
• Use a PC board with at least two layers; it should be
as free from voids as possible.
• Keep signal lines as short and as straight as possible.
Do not make 90° turns; round all corners.
