Preliminary Data Sheet
SPM-2045 High Linearity Mixer
Input IP3, SPM 2045, LO Power = +17 dBm
With variations in IF port match
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33
32
31
30
29
28
27
26
25
2 cm
4 cm
6 cm
8 cm
10 cm
12 cm
14 cm
16 cm
18 cm
20 cm
22 cm
24 cm
26 cm
28 cm
30 cm
31
30
29
IIP3 (dBm)
Input IP3, +17 dBm LO Power, 150 MHz IF
With variation in RF port match
IIP3 (dBm)
1750 MHz
1800 MHz
1850 MHz
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27
26
25
24
0
2
4
6
8
10
12
14
16
18
20
22
Tuner Length (cm)
1750 MHz
1800 MHz
1850 MHz
Trombone extension length
Sensitivity to Port Match
These graphs demonstrate the sensitivity of the linearity of the SPM-2045 to the impedance of the source which drives the
RF port, and the load that the IF port sees. In this case, the mixer is operated as a down-converter with LO drive of 17dBm
and an IF frequency of 150MHz. Three LO frequencies are shown.
In the left graph, a variable-length 50 ohm transmission line ("trombone") is placed between the IF port of the mixer and a 2
dB, open-circuited attenuator to provide a 4dB return loss to the IF port. The length of the transmission line is changed to
vary the phase of the reflection coefficient, thus providing a variable impedance. This graph shows how the input TOI varies
with the phase of the reflection coefficient. Notice that significant degradation in TOI can occur with mismatch, depending on
the phase of the mismatch.
In the right graph, a double-stub tuner is placed between the RF source and the mixer in order to provide a non-50 ohm
impedance to the RF port. The stub separation was adjusted to provide a reflection coefficient of approximately -4 dB. The
tuner length was changed to vary the phase of the reflection coefficient, thus providing a variable impedance. This graph
shows how the input TOI varies with the phase of the reflection coefficient on the RF port. Note that the TOI is very tolerant of
variations in load impedance, showing a change of only 3dB.
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8
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EDS102972 Rev A
STANFORD [ STANFORD MICRODEVICES ]
