Measuring Switch Perormance - Analog Devices ADGM1004EBZ User Manual

EVAL-ADGM1004EBZ User Guide
MEASURING SWITCH PERFORMANCE
Figure 1 shows the EVAL-ADGM1004EBZ
the ADGM1004. Apply a V
DD
measure the performance of the switch. The links are set
according to the switch under test (see Table 3). After selecting
the desired channel and its state, the switch performance data
can be collected using a network analyzer. Terminate the RFx
edge connectors of unused switch channels into 50 Ω loads to
achieve the full performance of the channel under test.
The EVAL-ADGM1004EBZ, shown in Figure 1, comes with a
calibration transmission line, CALIBRATION THRU, on the
PCB. This calibration line removes the insertion loss and phase
offset of the PCB transmission lines connecting to the switch from
the measurement. Figure 2 shows the calibration transmission line
and Figure 3 shows its insertion loss and return loss up to 16 GHz.
The calibration line is exactly the same length as the distance
from any one RFx connector to the RFx pin of the device, plus
the distance from the RFC connector to the RFC pin of the device.
Figure 2. EVAL-ADGM1004EBZ Calibration Transmission Line Used for PCB
Insertion Loss and Phase Offset Correction
0
–0.5
S(2,1)
–1.0
–1.5
S(1,1)
–2.0
–2.5
–3.0
0 2.5 5.0
FREQUENCY (GHz)
Figure 3. Calibration Transmission Line Insertion Loss and Return Loss
evaluation board of
supply to the evaluation board to
0
–10
–20
–30
–40
–50
7.5 10.0 12.5 15.0
Figure 4 illustrates the calibration line length. All RF traces
connecting to the
Figure 4. Calibration Transmission Line Length Equal to the A + B Length
To deembed the PCB transmission line insertion loss from the
entire switch insertion loss board measurement (the RF1 to
RFC path), divide the S(2,1) of measured data by the |S(2,1)| of
the CALIBRATION THRU line. Perform this deembedding by
using the network analyzer at the time of the measurement or after
the measurement using individual measurement data files. Refer
to the Network Analyzer Calibration Procedure section for
more information.
Use the network analyzer port extension function to deembed
the phase offset introduced by the PCB transmission lines. The
port extension method uses time delay offset values to correct
for phase. Enter the time delays into the port extension menu
on the network analyzer corresponding to the phase offset
introduced from an RF edge connector to the switch pin. Figure 4
shows an example of these phase offsets on a typical switch
measurement, labeled as A and B. Both A and B are identical in
length and can be calculated by measuring the time delay of the
calibration line and dividing it by two.
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ADGM1004 are of equal length.
A
B
UG-1078