MAX9993
Detailed Description
The MAX9993 high-linearity down-conversion mixer pro-
vides 8.5dB of gain and +23.5dBm IIP3, with a 9.5dB
noise figure (typ). Integrated baluns and matching cir-
cuitry allow 50Ωsingle-ended interfaces to the RF and
LO ports. A single-pole, double-throw (SPDT) LO switch
provides 50ns switching time between LO inputs, with
typically 40dB LO-to-LO isolation. Furthermore, the inte-
grated LO buffer provides a high drive level to the mixer
core, reducing the LO drive required at the MAX9993’s
inputs to 0dBm to +6dBm range. The IF port incorpo-
rates a differential output, which is ideal for providing
enhanced IIP2 performance.
Specifications are guaranteed over broad frequency
ranges to allow for use in UMTS and 2G/2.5G/3G
DCS1800 and PCS1900 base stations. The MAX9993 is
specified to operate over an RF input range of
1700MHz to 2200MHz, an LO range of 1400MHz to
2000MHz, and an IF range of 40MHz to 350MHz. This
device can operate in high-side LO injection applica-
tions with an extended LO range, but performance
degrades gently as fLO continues to increase. See the
Typical Operating Characteristics for measurements
taken with fLO up to 2400MHz. This device is available
in a compact 5mm ✕5mm 20-pin thin QFN package
with an exposed pad.
RF Input and Balun
The MAX9993 has one input (RF) that is internally
matched to 50Ω, requiring no external matching com-
ponents. A DC-blocking capacitor is required, because
the input is internally DC shorted to ground through the
on-chip balun. Input return loss is better than 15dB over
the entire RF frequency range of 1700MHz to 2200MHz.
LO Input, Switch, Buffer, and Balun
The mixer can be used for either high-side or low-side
injection applications with an LO frequency range of
1400MHz to 2000MHz. An internal LO SPDT switch
selects one of two single-ended LO ports. This allows
the external oscillator to settle on a particular frequency
before it is switched in. LO switching time is guaran-
teed to be less than 50ns. This switch is controlled by a
digital input (LOSEL): logic low selects LO1, logic high
selects LO2. LO1 and LO2 inputs are internally
matched to 50Ω, requiring only a 22pF DC-blocking
capacitor.
A two-stage internal LO buffer allows a wide input power
range for the LO drive. All guaranteed specifications are
for an LO signal power from 0dBm to +6dBm. A low-loss
balun along with an LO buffer drives the double-balanced
mixer. All interfacing and matching from the LO inputs to
the IF outputs are integrated on-chip.
High-Linearity 1700MHz to 2200MHz Down-
Conversion Mixer with LO Buffer/Switch
8 _______________________________________________________________________________________
balun. Provide a DC-blocking capacitor if required.
inductance connection between the exposed paddle (EP) and the PC board ground.
carries approximately 100mA DC current.