MAX2361EGM-D Maxim Integrated Products, MAX2361EGM-D Datasheet - Page 23

• Manufacturer Part Number: MAX2361EGM-D
• Description: RF Transmitter Complete Dual-Band Q uadrature Transmitte
• Manufacturer: Maxim Integrated Products

Specifications of MAX2361EGM-D

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

High-frequency bypass capacitors are required close
to the pins with a dedicated via to ground. The 48-pin
QFN-EP package provides minimal inductance ground
by using an exposed paddle under the part. Provide at
least five low-inductance vias under the paddle to
ground, to minimize ground inductance. Use a solid
ground plane wherever possible. Any cutout in the
ground plane may act as slot radiator and reduce its
shield effectiveness.
Keep the RF LO traces as short as possible to reduce
LO radiation and susceptibility to interference.
The low-band tank (TANKL+, TANKL-) and high-band
tank (TANKH+, TANKH-) are fully differential. The exter-
nal tank components are shown in Figure 6. The fre-
quency of oscillation is determined by the following
equation:
C
C
C
C
and traces
C
quency
C
Table 10 shows possible component values for various
oscillation frequencies.
Internal to the IC, the charge pump will have a leakage
of less than 10nA. This is equivalent to a 300MΩ shunt
Figure 5. 3-Wire Interface Diagram
C
f
OSC
INT
D
VAR
PAR
CENT
C
VAR
= Capacitance of varactor
= External coupling capacitor to the varactor
= Internal capacitance of TANK port
= Equivalent variable tuning capacitance
= Parasitic capacitance due to PC board pads
=
= External capacitor for centering oscillation fre-
=
2
π
2 (C
C
D
(C
D
INT
×
______________________________________________________________________________________
CLK
+ C )
CS
DI
C
C
+
C
B19 (MSB)
C
t
CENT
CS
1
+
B18
C
IF Tank Design
VAR
+
t
CH
C
PAR
B0
) L
Quadrature Transmitters
A3
resistor. The charge-pump output must see an
extremely high DC resistance of greater than 300MΩ.
This minimizes charge-pump spurs at the comparison
frequency. Make sure there is no solder flux under the
varactor or loop filter.
The MAX2361/MAX2363/MAX2365 EV kit can be used
as a starting point for layout. For best performance,
take into consideration power-supply issues as well as
the RF, LO, and IF layout.
To minimize coupling between different sections of the
IC, the ideal power-supply layout is a star configuration,
which has a large decoupling capacitor at a central
V
each going to a separate V
MAX2363/MAX2365 circuit. At the end of each trace is
a bypass capacitor with impedance to ground less than
1Ω at the frequency of interest. This arrangement pro-
Figure 6. Tank Port Oscillator
CC
node. The V
t
CWL
t
C
C
Complete Dual-Band
CWH
D
D
A1
C
C
C
C
C
CENT
CC
A0 (LSB)
t
EW
t
ES
traces branch out from this node,
L
Power-Supply Layout
CC
C
PAR
node in the MAX2361/
Layout Issues
t
t
t
t
t
t
CS
CH
CWH
ES
CWL
EW
> 50ns
> 50ns
> 10ns
> 50ns
> 50ns
> 50ns
C
INT
MAX2361
MAX2363
MAX2365
-R
n
23