Datasheet

To avoid damage to the part, voltage MUST be applied
to V
CC
before digital logic is applied to LOSEL (see the
Absolute Maximum Ratings ). LO1 and LO2 inputs are
internally matched to 50Ω, requiring an 82pF DC-block-
ing capacitor at each input.
A two-stage internal LO buffer allows a wide input-
power range for the LO drive. All guaranteed specifica-
tions are for a -3dBm to +3dBm LO signal power. 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 MAX2031 is a double-balanced, high-
performance passive mixer. Exceptional linearity is pro-
vided by the large LO swing from the on-chip LO buffer.
Differential IF
The MAX2031 mixer has a DC to 250MHz IF frequency
range. Note that these differential ports are ideal for pro-
viding enhanced IIP2 performance. Single-ended IF
applications require a 1:1 balun to transform the 50Ω dif-
ferential IF impedance to 50Ω single-ended. Including
the balun, the IF return loss is better than 15dB. The dif-
ferential IF is used as an input port for upconverter oper-
ation. The user can use a differential IF amplifier following
the mixer, but a DC block is required on both IF pins.
Applications Information
Input and Output Matching
The RF and LO inputs are internally matched to 50Ω. No
matching components are required. As a downconvert-
er, the return loss at the RF port is typically better than
15dB over the entire input range (650MHz to 1000MHz),
and return loss at the LO ports are typically 15dB
(960MHz to 1180MHz). RF and LO inputs require only
DC-blocking capacitors for interfacing (see Table 1).
An optional L-C bandpass filter (BPF) can be installed at
the RF port to improve upconverter performance. See
the
Typical Application Circuit and Typical Operating
Characteristics
for upconverter operation with an L-C
BPF tuned for 810MHz RF frequency. Performance can
be optimized at other frequencies by choosing different
values for L1 and C4. Removing L1 and C4 altogether
results in a broader match, but performance degrades.
Contact factory for details.
The IF output impedance is 50Ω (differential). For eval-
uation, an external low-loss 1:1 (impedance ratio) balun
transforms this impedance to a 50Ω single-ended out-
put (see the
Typical Application Circuit).
Bias Resistor
Bias current for the LO buffer is optimized by fine tun-
ing resistor R1. If reduced current is required at the
MAX2031
High-Linearity, 650MHz to 1000MHz Upconversion/
Downconversion Mixer with LO Buffer/Switch
______________________________________________________________________________________ 17
DESIGNATION QTY DESCRIPTION SUPPLIER
82pF microwave capacitor (0603).
Use for 800MHz/900MHz cellular band applications.
C1 1
7pF microwave capacitor (0603).
Use for 700MHz band applications
Murata Electronics North America, Inc.
C2, C7, C8, C10,
C11, C12
6 82pF microwave capacitors (0603) Murata Electronics North America, Inc.
C3, C6, C9 3 0.01µF microwave capacitors (0603) Murata Electronics North America, Inc.
C4* 1 6pF microwave capacitor (0603) —
2pF microwave capacitor (0603).
Use for 800MHz/900MHz cellular band applications.
C5** 1
3.3pF microwave capacitor (0603).
Use for 700MHz band applications
Murata Electronics North America, Inc.
L1* 1 4.7nH inductor (0603) —
R1 1 523Ω ±1% resistor (0603) Digi-Key Corp.
T1 1 MABAES0029 1:1 transformer (50:50) M/A-Com, Inc.
U1 1 MAX2031 IC (20 TQFN) Maxim Integrated Products, Inc.
Table 1. Typical Application Circuit Component List
* C4 and L1 installed only when mixer is used as an upconverter.
** C5 installed only when mixer is used as a downconverter.