EQCO62R20.3 Datasheet, PDF (12/34 Pages) Microchip Technology – EQCO62R20.3 6.25 Gbps Asymmetric Coax Equalizer

EQCO62R20.3/EQCO31R20.3
2.1.2
MULTILANE COAXPRESS 4+1
LAYOUT WITH DIN1.0/2.3
CONNECTORS
Figure 2-3 shows an example of a Multilane
CoaXPress 4+1 setup. The recommended Din1.0/2.3
connector is the NPF 4076 from Cambridge
Connectors. The cable example shows the pitches in
millimeters. Figure 2-4 shows the four layers of the
recommended footprints and off-chip components that
are critical for RF-performance of the cable drivers
CD_1 to CD_4 at the camera side, which have Power
over CoaXPress (PoCXP). Figure 2-5 shows the
variant without PoCXP used for CD_5 at the host side.
The exact dimensions in millimeters are given in
Section 4.1 “Package Marking Information”. It is
recommended to copy these dimensions, especially
the connection between the DIN1.0/2.3 connector and
the chip, as this is a complex entity with coupled
currents and compensated parasitic capacitances.
Despite the critical layout, this proposed layout is
designed to be largely independent of the used PCB-
layer stack, as the critical parts are mainly the top-layer
only. This will work as well for four, six or even higher
numbers of layers. Possible extra layers should have
cut-outs as large as the full proposed footprint.
In these layouts, the size of the PCB area needed for
the chip is minimized. This allows multiple lanes
close together.
Only two of four connector GND pins are connected to
the GND plane to reduce the capacitance.
The differential CD inputs must be a 100Ω differential
transmission line. A cut-out of the ground and power
plane underneath the input pins is recommended to
minimize the parasitic capacitance. For best
performance, no vias should be used in this high-speed
signal path.
The Components Express 4+1 connector in Figure 2-3 is
only shown as an example. Other connector
configurations are available with DIN1.0/2.3 connectors
such as 6+1, 2+1, 1+1, dual- or single-lane configurations.
DS60001302B-page 12
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