MAX9627 Maxim, MAX9627 Datasheet - Page 17

• Manufacturer Part Number: MAX9627
• Description: The MAX9626/MAX9627/MAX9628 are low-noise, low-distortion, and high-bandwidth differential amplifier/ADC drivers for use in applications from DC to 1
• Manufacturer: Maxim

The input referred voltage noise specification reported
in the Electrical Characteristics table includes both the
noise contribution of the amplifier and the contribution of
all the internal resistive elements. Because such resistive
elements change depending on the gain selection as
per Table 1, the input voltage noise specification differs
according to the gain options.
The ICs feature an input, VOCM, that sets the differential
output common-mode voltage. Its wide range from 1.1V
to V
most of the high-speed pipeline differential input ADCs.
While many of these ADCs accept an input common-
mode around half of their supply voltage, some of them
have input common-mode range shifted toward either
ground or the positive supply.
The ICs can comfortably drive both 3.3V and 5V ADCs
that have common-mode range around half supply.
When powered with V
also drive some of the popular ADCs with common-mode
range higher than 3V.
The high bandwidth of VOCM makes the amplifier's out-
put recover quickly from load transient conditions. Such
conditions may occur when switching the ADC input
capacitor during the track-and-hold phases. The input
capacitor switching may cause a voltage glitch at the
input of the ADC, which incurs a load transient condition
for the driving amplifier.
The ICs are high-speed devices, sensitive to the PCB
environment in which they operate. Realizing their superior
performance requires attention to the details of high-
speed PCB design.
The first requirement is a solid continuous ground plane
on the second PCB layer, preferably with no signal or
power traces. PCB layers 3 and 4 can be power-supply
routing or signal routing, but preferably they should not
be routed together.
Setting the Output Common-Mode Voltage
CC
- 1.1V makes the amplifier family compatible with
CC
Power-Supply Decoupling
and Layout Techniques
of 5V or higher, the ICs can
1.35GHz Fully Differential Amplifiers
Input Voltage Noise
Low-Noise, Low-Distortion,
For power-supply decoupling with single-supply opera-
tion, place a large capacitor by the V
and then place a smaller capacitor as close as possible
to the V
good values to use. When used with split supplies, place
relevant capacitors on the V
Ground vias are critical to provide a ground return path
for high frequency signals and should be placed near
the decoupling capacitors. Place ground vias on the
exposed pad as well, along the edges and near the pins
to shorten the return path and maximize isolation. Vias
should also be placed next to the input and output signal
traces to maximize isolation. Finally, make sure that the
layer 2 ground plane is not severely broken up by signal
vias or power supply vias.
Signal routing should be short and direct to avoid
parasitic effects. For very high-frequency designs, avoid
using right angle connectors since they may introduce
a capacitive discontinuity and ultimately limit the fre-
quency response.
The MAX9626/MAX9627/MAX9628 family offers excel-
lent bandwidth and distortion performance that is in line
with the majority of high-speed and 16-bit resolution
pipeline ADCs in the market. In particular, it is recom-
mended in combination with the MAX19586/MAX19588
family of 16-bit and 100Msps pipeline ADCs.
For lower resolution applications, the MAX9626/
MAX9627/MAX9628 family can also drive 10- to 14-bit
ADCs such as the MAX12553/MAX12554/MAX12555,
MAX12527/MAX12528/MAX12529
MAX19506/MAX19507 families.
CC
pin. For 1GHz decoupling, 22pF to 100pF are
Recommended Pipeline ADCs
EE
supply as well.
and
CC
supply node
MAX19505/
17