LT5579IUH-PBF LINER [Linear Technology], LT5579IUH-PBF Datasheet - Page 17

• Manufacturer Part Number: LT5579IUH-PBF
• Description: 1.5GHz to 3.8GHz High Linearity Upconverting Mixer
• Manufacturer: LINER [Linear Technology]

TYPICAL APPLICATIONS
The RF port impedance match was realized with C8 =
1.5pF and L3 = 6.8nH. The optimum impedance match
was purposefully shifted high in order to achieve better
OIP3 performance at the desired frequency.
Figure 9 shows the measured conversion gain and OIP3
as a function of RF output frequency. As mentioned above,
the output impedance match is shifted towards the high
side of the band, and this is evidenced by the positive slope
of the gain. The single sideband noise fi gure across the
frequency range is also shown.
Curves for both high side and low side LO cases are
shown. In this particular application, the low side OIP3
outperforms the high side case.
Figure 9. Gain, Noise Figure and OIP3 vs
RF Frequency with 70MHz IF and 1650MHz RF
35
30
25
20
15
10
–5
5
0
1550
T
f
P
P
IF
A
IF
LO
= 70MHz
= 25°C
= –5dBm/TONE
= –1dBm
RF OUTPUT FREQUENCY (MHz)
1600
SSB NF
GAIN
OIP3
1650
LOW SIDE LO
HIGH SIDE LO
1700
5579 F09
1750
1950MHz Application
In this example, a high side LO was used to convert the IF
input signal at 240MHz to 1950MHz at the RF output. The
RF port impedance match was realized with C8 = 1pF and
L3 = 4.7nH. As in the 1650MHz case, it was found that
tuning the output match slightly high in frequency gave
better OIP3 results at the desired frequency. The input
match for 240MHz operation is the same as described in
the test circuit of Figure 1.
The measured 1950MHz performance is plotted in Fig-
ure 10 for both low side and high side LO drive. With this
matching confi guration, the low side LO case outperforms
the high side LO. The gain, noise fi gure (SSB) and OIP3
are plotted as a function of RF output frequency.
Figure 10. Gain, Noise Figure and OIP3 vs
RF Frequency for the 1950MHz Application
35
20
15
30
25
10
5
0
1800
T
f
P
P
IF
A
IF
LO
= 240MHz
= 25°C
= –5dBm/TONE
= –1dBm
1850
RF OUTPUT FREQUENCY (MHz)
1900
SSB NF
OIP3
GAIN
1950
LOW SIDE LO
HIGH SIDE LO
2000
5579 F10
2050
LT5579
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