lt5560 Linear Technology Corporation, lt5560 Datasheet - Page 17

• Manufacturer Part Number: lt5560
• Description: 0.01mhz To 4ghz Low Power Active Mixer
• Manufacturer: Linear Technology Corporation

Table 3 lists actual component values used on the LT5560
evaluation boards for impedance matching at various
frequencies. The measured Input Return Loss vs Fre-
quency performance is plotted for several of the cases
in Figure 6.
Table 3. Component Values for Input Matching
Note 1: Series 5.6pF capacitor is used at the input (see Figure 3).
CASE
1
2
3
4
5
6
7
8
9
FREQ.
(MHz)
1900
2450
3600
450
140
240
900
10
70
Figure 6. Input Return Loss vs Frequency
for Different Matching Values
1
–20
–25
–30
–10
–15
–5
0
10
HHM1522B1 1:1
HHM1520A2 2:1
HHM1583B1 2:1
WBC1-1TL 1:1
WBC1-1TL 1:1
WBC1-1TL 1:1
WBC1-1TL 1:1
WBC1-1TL 1:1
HHM1526 2:1
1
T1
FREQUENCY (MHz)
100
2
3
4
(pF)
220
NA
2.2
0.5
C1
39
22
15
1
1
5
1000
6
L1, L2
(nH)
180
33
18
12
0
0
0
0
0
5560 F06
7
4000
9
(@12dB RL)
MATCH BW
1660-2500
1640-2580
3330-3840
710-1630
115-295
390-560
29-102
50-190
6-18
LO Input Port
Figure 7 shows a simplifi ed schematic of the LO input. The
LO input connections drive the bases of the mixer transis-
tors, while a 200Ω resistor across the inputs provides the
impedance termination. The internal 1kΩ bias resistors are
in parallel with the input resistor resulting in a net input
DC resistance of approximately 180Ω. The pins are biased
by an internally generated voltage at approximately
1V below V
required. If desired, the LO inputs can be driven differen-
tially. The required LO drive at the IC is 240mV
which can come from a 50Ω source or a higher impedance
such as PECL.
LO
50Ω
IN
C3
C7
CC
L5
; thus external DC blocking capacitors are
Figure 7. LO Input Schematic
C5
C4
8
1
LT5560
V
LO
LO
CC
+
–
1k
200Ω
LT5560
RMS
1k
17
V
BIAS
(typ)
5560 F07
5560f