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Maxim Integrated Products 47
MAX2042A
SiGe High-Linearity, 1600MHz to 3900MHz
Upconversion/Downconversion Mixer with LO Buffer
Functional Diagram
Detailed Description
When used as a high-side LO injection mixer in the
2300MHz to 2900MHz band, the MAX2042A provides
+33dBm of IIP3, with typical conversion loss and noise
figure values of only 7.2dB and 7.25dB, respectively.
The integrated baluns and matching circuitry allow for
50I single-ended interfaces to the RF and the LO port.
The integrated LO buffer provides a high drive level to
the mixer core, reducing the LO drive required at the
IC’s input to a -6dBm to +3dBm range. The IF port incor-
porates a differential output, which is ideal for providing
enhanced 2LO - 2RF performance.
Specifications are over broad frequency ranges to allow
for use in GSM/EDGE, CDMA, TD-SCDMA, WCDMA, LTE,
TD-LTE, WiMAX, and MMDS base stations. The device
is specified to operate over a 1600MHz to 3900MHz
RF input range, a 1300MHz to 4000MHz LO range,
and a 50MHz to 500MHz IF range. The external IF
components set the lower frequency range (see the
beyond these ranges is possible (see the
TypicalRF Input and Balun
The IC’s RF input provides a 50I match when combined
with a series DC-blocking capacitor. This DC-blocking
capacitor is required as the input is internally DC shorted
to ground through the on-chip balun. When using an
8.2pF DC-blocking capacitor, the RF port input return
loss is typically 17dB over the 2300MHz to 2900MHz
RF frequency range. A return loss of 14dB over the
3000MHz to 3900MHz range is achieved by changing
the DC-blocking capacitor to 1.5pF.
For applications spanning the 1700MHz to 2200MHz
frequency range, a 12nH shunt inductor can be used
in conjunction with a 1.8pF DC-blocking capacitor to
provide a typical return loss of 12dB. See the
TypicalLO Inputs, Buffer, and Balun
With a broadband LO drive circuit spanning 1300MHz to
4000MHz, the device can be used in either low- or high-
side LO injection architectures for virtually all 1.7GHz to
3.5GHz receiver and transmitter applications. The LO
input is internally matched to 50I, requiring only a 2pF
DC-blocking capacitor. A two-stage internal LO buffer
allows for a -6dBm to +3dBm LO input power range. The
on-chip low-loss balun, along with an LO buffer, drives
the double-balanced mixer. All interfacing and match-
ing components from the LO inputs to the IF outputs are
integrated on-chip.
High-Linearity Mixer
The core of the device is a double-balanced, high-
performance passive mixer. Exceptional linearity is
provided by the large LO swing from the on-chip LO buffer.
IIP3, 2LO - 2RF rejection, and noise-figure performance
are typically 33dBm, 72dBc, and 7.25dB, respectively.
Differential IF Ports
The device has a 50MHz to 500MHz IF frequency range,
where the low-end frequency depends on the frequency
response of the external IF components.
The device’s differential IF ports are ideal for providing
enhanced 2LO - 2RF performance. The user can connect
a differential IF amplifier or SAW filter to the mixer IF
port, but a DC block is required on both IF+/IF- ports to
keep external DC from entering the IF ports of the mixer.
To characterize the part, an external MABACT0069 1:1
transformer is used to transform the 50I differential IF
interface to 50I single-ended. Its loss is included in the
data presented in this data sheet. This transformer also
supplies a needed IF pin ground return for the on-chip
circuitry. If a ground return is not available on the IF pins,
the return is achievable through some off-chip resistance
to ground or large-value inductors. A 1kI to ground
on each IF pin can be used for such an application.
In addition, the IF interface directly supports single-
ended, AC-coupled signals into or out of IF+ by shorting
IF- to ground and using a 1kI resistor from IF+ to ground.
RF
IF
RF BALUN
LO BALUN
LO DRIVER
LO
MAX2042A