DC1437B-AA Linear Technology, DC1437B-AA Datasheet - Page 15

• Manufacturer Part Number: DC1437B-AA
• Description: BOARD EVAL LTM9003-AA
• Manufacturer: Linear Technology
• Type: Pre-Distortion Receiver Subsystemr

Specifications of DC1437B-AA

• Design Resources: DC1437 Schematic
• Frequency: 184MHz
• Features: LTM9003 12bit Predistortion Receiver Subsystem
• Tool / Board Applications: Wireless Connectivity-ZigBee, RF, Infrared, USB
• Mcu Supported Families: LTM9003
• Development Tool Type: Hardware - Eval/Demo Board
• For Use With/related Products: LTM9003
• Lead Free Status / RoHS Status: Not applicable / Not applicable

applicaTions inForMaTion
RF Input Port
The mixer’s RF input is shown in Figure 4 and is internally
matched from 1.1GHz to 1.8GHz, requiring no external
components over this frequency range. The input return
loss, shown in Figure 5, is typically 12dB at the band edges.
The input match at the lower band edge can be optimized
with a shunt 3.3pF capacitor at Pin G1, which improves
the 0.8GHz return loss to greater than 25dB. Likewise,
the 2GHz match can be improved to greater than 25dB
with a series 3.9nH inductor and a 1pF shunt capacitor.
Measured RF input return losses for these three cases are
plotted in Figure 5.
Figure 5. RF Input Return Loss with and without Matching
RF
RF
IN
IN
FOR 450MHz, 900MHz
LOW-PASS MATCH
and 3.6GHz RF
–10
–15
–25
–30
–20
–5
L = L (mm)
0
Z
100
L5
O
C5
= 50
C5
Figure 4. RF Input Schematic
HIGH-PASS MATCH
FOR 2.6GHz RF
AND WIDEBAND RF
LTM9003
FREQUENCY (MHz)
RF
1000
800MHz MATCH
(3.3pF)
NO MATCHING
ELEMENTS
2GHz MATCH
(3.9nH + 1pF)
9003 F05
10000
9003 F04
TO
MIXER
This series transmission line/shunt capacitor matching
topology allows the LTM9003 to be used for multiple
frequency standards without circuit board layout modifica-
tions. The series transmission line can also be replaced
with a series chip inductor for a more compact layout.
RF input impedance and S11 versus frequency (with no
external matching) are listed in Table 1 and referenced
to Pin G1. The S11 data can be used with a microwave
circuit simulator to design custom matching networks and
simulate board-level interfacing to the RF input filter.
Table 1a. RF Input Impedance vs Frequency (LTM9003-AA)
FREQUENCY
(MHz)
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
3000
500
600
700
800
900
INPUT IMPEDANCE
23.6 + j6.7
27.1 + j6.1
30.8 + j5.3
34.9 + j4.2
39.4 + j2.9
44.6 + j1.4
61.5 – j1.2
68.7 + j1.4
67.5 + j4.5
64.3 + j4.7
60.8 + j4.1
56.7 + j2.8
52.7 + j1.2
48.6 – j0.6
44.7 – j2.3
33.1 – j6.3
29.4 – j6.9
22.9 – j6.7
20.3 + j7
66 – j0.3
69 + j3.2
40.8 – j4
37 – j5.3
56 – j1
26 – j7
50.1
MAG
0.57
0.53
0.48
0.43
0.38
0.33
0.28
0.22
0.17
0.14
0.14
0.17
0.22
0.27
0.32
0.36
0.43
0.46
0.48
0.51
0.52
0.53
0.53
0.53
0.4
0.5
LTM9003
S11
–104.3
–110.5
–117.2
–124.3
–131.7
–139.6
ANGLE
137.9
132.7
120.4
112.6
102.8
–21.5
–64.3
–72.2
–79.5
–85.8
–92.1
89.8
70.4
42.2

143
127
–41
–54
–98
6.6
9003f