Datasheet

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MAX2042A
SiGe High-Linearity, 1600MHz to 3900MHz
Upconversion/Downconversion Mixer with LO Buffer
Applications Information
Input and Output Matching
The RF input provides a 50I match when combined
with a series DC-blocking capacitor. Use an 8.2pF capac-
itor value for RF frequencies ranging from 2000MHz to
2900MHz. Use a 1.5pF capacitor value to match the
RF port for the 3000MHz to 3900MHz band. For RF
frequencies in the 1650MHz to 2250MHz range, use
C1 = 1.8pF and L1 = 12nH. The LO input is internally
matched to 50I, so use a 2pF DC-blocking capacitor
to cover operations spanning the 1300MHz to 4000MHz
range. The IF output impedance is 50I (differential).
For evaluation, an external low-loss 1:1 (impedance
ratio) balun transforms this impedance down to a 50I
single-ended output (see the Typical Application Circuit).
Reduced-Power Mode
The device includes a pin (LOBIAS) that allows an exter-
nal resistor to set the internal bias current. A nominal
value for this resistor is given in Tables 1 and 2. Larger-
value resistors can be used to reduce power dissipa-
tion at the expense of some performance loss. If Q1%
resistors are not readily available, substitute with Q5%
resistors.
Significant reductions in power consumption can also be
realized by operating the mixer with an optional supply
voltage of 3.3V. Doing so reduces the overall power
consumption by up to 42%. See the 3.3V Supply AC
Electrical Characteristics tables and the relevant 3.3V
curves in the Typical Operating Characteristics section to
evaluate the power vs. performance tradeoffs.
Layout Considerations
A properly designed PCB is an essential part of any
RF/microwave circuit. Keep RF signal lines as short as
possible to reduce losses, radiation, and inductance.
For the best performance, route the ground pin traces
directly to the exposed pad under the package. The PCB
exposed pad MUST be connected to the ground plane
of the PCB. It is suggested that multiple vias be used to
connect this pad to the lower-level ground planes. This
method provides a good RF/thermal conduction path for
the device. Solder the exposed pad on the bottom of the
device package to the PCB.
Power-Supply Bypassing
Proper voltage-supply bypassing is essential for high-
frequency circuit stability. Bypass each V
CC
pin with the
capacitors shown in the Typical Application Circuit and
see Table 1.
Exposed Pad RF/Thermal
Considerations
The exposed pad (EP) of the device’s 20-pin TQFN
package provides a low thermal-resistance path to the
die. It is important that the PCB on which the device is
mounted be designed to conduct heat from the EP. In
addition, provide the EP with a low-inductance path to
electrical ground. The EP MUST be soldered to a ground
plane on the PCB, either directly or through an array of
plated via holes.