NB3N1200KMNGEVB, NB3W1200LMNGEVB
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5
Differential Clock Inputs and Outputs
CLK_IN & CLK_IN# - Differential Clock Inputs
The differential Clock input traces, CLK_IN/CLK_IN#,
are equal length routed straight from the SMA connectors on
the left side directly to the DUT; there are no vias on metal
traces.
CLK_IN & CLK_IN# have resistor pads (R51 & R52) to
GND to terminate a signal generator, if used. 50-ohm
resistors are installed. Remove these resistors if CLK_IN
& CLK_IN# are driven by another IC device.
DIF_n and DIF_n# - Differential Outputs
NB3N1200KMNGEVB and NB3W1200LMNGEVB
were designed with a flexible PCB layout configuration to
measure the differential HCSL (1200K) or Push-Pull
(1200L) outputs with a 50-ohm scope head or
high-impedance FET probe. (See Output Layout in
Figures 8 and 9)
Six of the twelve differential outputs are designed to have
equal length metal traces from the device pins to the SMA
connectors.
The other six differential outputs have shortened metal
traces, do not have SMA connectors and can be observed
with a high-impedance probe on the metal pads provided.
Each DIF_n/DIF_n# output has a provision for C
Load
;
2 pF capacitors are installed on all outputs.
Rs & Rp pads are located close to the DUT. Rs = 33-
W
is
installed for both the NB3N1200K and NB3W1200L.
NB3N1200K (HCSL Outputs)
RP is not installed on the six output pair with long metal
traces to SMA connectors; Use 50-
W
to GND of the
oscilloscope head for RP.
Rp is installed (50-
W
to GND) on the short metal traces
without SMA connectors and will use Hi-Z probes.
NB3W1200L (Push-Pull Outputs)
Rp is not installed
Table 2. NB3N1200KMNGEVB AND NB3W1200LMNGEVB OUTPUT LOAD AND TERMINATION
VS. OSCILLOSCOPE MEASUREMENT
Device
Output Traces
Rs
Rp
CLoad
Scope
1200K
Long
33-
W
Open (DNI)
2 pF
50-
W
1200K
Short
33-
W
50-
W
2 pF
Hi-Z
1200L
Long or Short
33-
W
Open (DNI)
2 pF
Hi-Z
Figure 9. Differential Outputs Schematic/PCB Configuration: Long vs. Short Metal Traces
From: DUT Output
From: DUT Output
Rs
Rp
Rs
Rp
GND
GND
CL
CL is at SMA
Connector
Long Output Traces:
Use 50-
W
Scope via SMA Connector
Short Output Traces:
Use High-Z Probe
DIF_5#
DIF_5
DIF_4#
DIF_4
DIF_4#
DIF_4
DIF_5#
DIF_5
D IF_4
D IF_5
DIF_N4
DIF_N5
OUT_N4
OUT4
OUT5
OUT_N5
R43
49.9
1
2
C9
2.0pF
1
2
PR6
R45
33
1
2
DIF_4
34
DIF_5
38
DIF_4#
35
DIF_5#
39
R47
1
2
TP19
J11
DIF_5
R125
0
1
2
TP20
J12
DIF_5#
C10
2.0pF
1
2
R33
33
1
2
R35
49.9
1
2
C11
2.0pF
1
2
0
1
2
R37
33
1
2
R39
49.9
1
2
R126
1
2
R46
0
1
2
1
2
R41
33
1
2
0
49.9
C12
2.0pF
R42
DIF_4
DIF_4#
