ADL5350-EVAL AD [Analog Devices], ADL5350-EVAL Datasheet - Page 22

• Manufacturer Part Number: ADL5350-EVAL
• Description: LF to 4 GHz High Linearity Y-Mixer
• Manufacturer: AD [Analog Devices]

ADL5350
HIGH FREQUENCY APPLICATIONS
The ADL5350 can be used at extended frequencies with some
careful attention to board and component parasitics. Figure 61
is an example of a 2.3 GHz to 2.5 GHz down-conversion using a
low-side LO. The performance of this circuit is depicted in
Figure 62. Note that the inductor and capacitor values are very
small, especially for the RF and IF ports. Above 2.5 GHz, it is
necessary to consider alternate solutions to avoid unreasonably
small inductor and capacitor values.
The typical networks used for cellular applications below
2.5 GHz utilize band-select and band-reject networks on the RF
and IF ports. At higher RF frequencies, these networks are not
easily realized using lumped element components (discrete Ls
and Cs). As a result, it is necessary to consider alternate filter
network topologies to allow more reasonable values of
inductors and capacitors.
–10
30
25
20
15
10
–5
2200
5
0
Figure 61. 2.3 GHz to 2.5 GHz Down-Conversion Schematic
Figure 62. Measured Performance for Circuit in Figure 61
ALL INDUCTORS
ARE 0302CS
SERIES FROM
COILCRAFT
Using Low-Side LO Injection and 374 MHz IF
RF
2250
IF
0.67nH
1.5nH
2300
RF FREQUENCY (MHz)
1pF
RF/IF
RF/IF
8
1
2350
1nF
0.7pF
IP1dB
GND2
IIP3
GC
ADL5350
7
2
4.7µF
3.0nH
LO
2400
VPOS
LOIN
3V
GAIN
6
3
100pF
2.1nH
100pF
2450
GND1
GND1
5
4
2500
12
9
6
3
0
–3
–6
–9
–12
Rev. PrC | Page 22 of 24
Figure 63 depicts a cross-over filter network approach to
provide isolation between the RF and IF ports for a down-
converting application. The cross-over network essentially
provides a high-pass filter to allow the RF signal to pass to the
RF/IF node (Pin 1 and Pin 8), while presenting a low-pass filter,
(which is actually band-pass when considering the DC blocking
capacitor, C
to be passed to the desired IF load.
When designing the RF and IF port networks, it is important to
remember that the networks share a common node (the RF/IF
pins). In addition, the opposing network presents some loading
impedance to the target network being designed. Classic audio
crossover filter design techniques can be applied to help derive
component values. However, some caution must be applied
when selecting component values. At high RF frequencies, the
board parasitics may significantly influence the final optimum
inductor and capacitor component selections. Some empirical
testing may be necessary to optimize the RF and IF port filter
networks. The performance of the circuit depicted in Figure 63
is provided in Figure 64.
30
28
26
24
22
20
18
16
14
3300 3350 3400 3450 3500 3550 3600 3650 3700 3750 3800
Figure 63. 3.3 GHz to 3.8 GHz Down-Conversion Schematic
Figure 64. Measured Performance for Circuit in Figure 63
ALL
INDUCTORS
ARE 0302CS
SERIES FROM
COILCRAFT
AC
). This allows the difference component (f
RF
IF
3.5nH
L1
Preliminary Technical Data
1.8pF
C2
1.2pF
RF FREQUENCY (MHz)
GAIN
C1
RF/IF
RF/IF
8
1
L2
1.5nH
C
100pF
AC
IP1dB
GND2
GC
ADL5350
7
2
4.7µF
VPOS
LOIN
LO
3V
6
3
100pF
3.8nH
3.5nH
100pF
GND1
GND1
5
4
IIP3
RF
–2
–3
–4
–5
–6
–7
–8
–9
–10
– f
LO
)