Description:
The uPG2012TB-EVAL-A evaluation board provides a quick and convenient means of evaluating
the performance of the NEC uPG2012TB switch. In addition to the device, the board provides DC
block capacitors, power supply bypass capacitors, and RF and DC connectors.
A DC block capacitor is required at all RF ports. On this board, two parallel capacitors of 22pF are
used for this purpose. This configuration minimizes the mismatch effect associated with the serial
capacitors over a wide frequency range. In a real application where the operation frequency
range is relatively narrow, one DC block capacitor usually is sufficient. The user should select the
appropriate capacitor value according to the operation frequencies and the type of capacitor
selected. Generally the performance of the switch circuit is not sensitive, to a certain extent, to
the value of DC block capacitors.
A 1000pF DC bypass capacitor is used on all control lines. For high speed applications the user
may choose smaller capacitance or no capacitor at all.
DC supply connectors:
P1 is control voltage V
dd
, P2 is V
cont
and pins P3 and P4 are the ground.
V
dd
and V
cont
should be connected to separate power supplies to provide the required control
logic.
RF connectors:
As indicated on the board, J1 is connected to the OUTPUT1 port, J2 is connected to the
OUTPUT2 port and J3 is connected to the INPUT port.
Information on Board Material:
The board material is 20 mil thick Duroid 6002. Its dielectric constant is 2.94.
Switch Logic Table:
The following table lists the logic table for switch states.
Vdd
H
H
Vcont
L
H
INPUT –
OUTPUT1
OFF
ON
INPUT –
OUTPUT2
ON
OFF
Insertion Loss of Through Board:
In assessing the insertion loss of the switch by measuring S21 of the evaluation board, it is
necessary to take into account the loss through the connectors and PCB trace. To this end a
through board was characterized to determine the board/connector loss. The table below lists the
board loss at different frequencies.
INPUT FREQUENCY (GHz)
0.5
1.0
1.5
2.0
2.5
BOARD LOSS (dB)
0.053
0.073
0.107
0.120
0.133
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