LTC559X View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LTC559X Datasheet PDF : 20 Pages
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LTC5567
Applications Information
frequency range is listed in Table 2. Measured LO input
return losses are shown in Figure 6. Finally, LO input im-
pedance and input reflection coefficient, versus frequency
is shown in Table 3.
Table 2. LO Input Matching Values vs LO Frequency Range
FREQUENCY (MHz)
C5 (pF)
C6 (pF)
285 to 392
330
33
338 to 415
330
22
415 to 505
56
18
525 to 635
27
10
645 to 803
15
7.5
800 to 1150
6.8
2.7
1000 to 4000
3.9
—
3000 to 4500
1.8
0.2
0
–5
Table 3. LO Input Impedance and S11 (At Pin 15, No External
Matching, Mixer Enabled)
FREQUENCY
(MHz)
INPUT
IMPEDANCE
S11
MAG
ANGLE
350
5.2 + j14.9
0.83
146.5
400
6.0 + j17.3
0.81
141.7
450
6.6 + j19.5
0.80
137.0
500
7.2 + j21.5
0.78
132.7
600
9.1 + j26.5
0.75
123.6
800
15.1 + j35.7
0.67
106.0
1000
24.9 + j43.6
0.58
89.5
1500
67.5 + j36.4
0.33
47.1
2000
61.7 – j4.2
0.11
–18.3
2500
40.3 – j7.1
0.13
–139.4
3000
31.7 + j1.8
0.23
173.1
3500
29.8 + j12.3
0.29
140.0
4000
31.5 + j22.9
0.35
113.2
4500
36.0 + j32.4
0.38
92.8
–10
–15
–20
–25
0.2
0.7 1.2 1.7 2.2 2.7 3.2
FREQUENCY (GHz)
C5 = 27pF, C6 = 10pF
C5 = 6.8pF, C6 = 2.7pF
C5 = 3.9pF
C5 = 1.8pF, C6 = 0.2pF
TC = 25°C
3.7 4.2 4.7
5567 F06
Figure 6. LO Input Return Loss
The LO buffers have been designed such that the LO input
impedance does not change significantly when the IC is
disabled. This feature only requires that supply voltage is
applied. The actual performance of this feature is shown
in Figure 7. As shown, the LO input return loss is better
than 10dB over the 1GHz to 4GHz frequency range when
the IC is enabled or disabled.
0
TC = 25°C
–2
C5 = 3.9pF
–4
–6
–8
–10
– 12
DISABLED
– 14
ENABLED
– 16
– 18
0.2 0.7 1.2 1.7 2.2 2.7 3.2 3.7 4.2 4.7
FREQUENCY (GHz)
5567 F07
Figure 7. LO Input Return Loss—Mixer Enabled and Disabled
IF Output
The IF output schematic with external matching compo-
nents is shown in Figure 8. As shown, the output is dif-
ferential open collector. Each IF output pin must be biased
at the supply voltage (VCC), which is applied through the
external matching inductors (L1 and L2) shown in Figure 8.
Each pin draws approximately 27.5mA of DC supply cur-
rent (55mA total).
5567f
13
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