MAX2683/MAX2684
3.5GHz Downconverter Mixers
with Selectable LO Doubler
12 ______________________________________________________________________________________
Detailed Description
The MAX2683/MAX2684 are double-balanced down-
converter mixers optimized for the 3.4GHz to 3.8GHz
frequency band. The MAX2683 is designed for down-
conversion to IF frequencies of 100MHz to 400MHz,
while the MAX2684 is designed for IF frequencies of
800MHz to 1000MHz. In addition, the devices include a
logic-level LO frequency doubler, an integrated LO fil-
ter, and externally programmable bias control circuitry.
RF Input
RFIN is a single-ended input that accepts frequencies
in the 3.4GHz to 3.8GHz range. It requires a matching
network and a DC-blocking capacitor that may be part
of this network. See Typical Operation Circuit for rec-
ommended component values. See Table 1 for RFIN
port S-parameters.
LO Inputs, LO Frequency Doubler,
and LO Filter
The MAX2683/MAX2684 feature an internal LO frequen-
cy doubler that allows the external LO to run at full or
half frequency. Running the LO at half frequency has
the benefit of reducing unwanted LO leakage through
the low-noise amplifier (LNA) to the antenna, reducing
injection pulling of the voltage-controlled oscillator
R
BIAS
= 2kΩ
S11 PHASE
(degrees)
-126.0
-124.7
-123.5
-122.3
3600
R
BIAS
= 1.2kΩ
S11 MAG
S11 PHASE
(degrees)
S11 MAG
0.570 -125.1 0.547
0.567 -123.7 0.544
0.564 -122.5 0.540
0.561 -121.3 0.536
R
BIAS
= 820Ω
RF
FREQUENCY
(MHz)
S11 MAG
S11 PHASE
(degrees)
3550 0.594 -117.5
3500 0.590 -116.2
3450 0.586 -114.8
3400 0.582 -113.3
0.599 -118.7 0.574 -126.1 0.553 -127.0
3650 0.602 -120.0 0.576 -127.2 0.555 -128.1
3700 0.607 -121.2 0.580 -128.3 0.559 -129.1
3750 0.608 -122.3 0.583 -129.3 0.563 -130.1
3800 0.612 -123.5 0.587 -130.2 0.567 -131.0
3400 0.578 -117.5 0.537 -119.7 0.512 -121.3
3450 0.582 -119.0 0.542 -121.2 0.518 -122.7
3500 0.586 -120.5 0.545 -122.6 0.523 -124.1
3550 0.590 -121.8 0.545 -122.7 0.527 -125.5
3600 0.595 -123.1 0.555 -125.4 0.533 -126.8
3650 0.599 -124.5 0.558 -126.7 0.537 -128.0
3700 0.604 -125.7 0.564 -127.8 0.542 -129.1
3750 0.606 -126.7 0.568 -128.9 0.546 -130.2
3800 0.611 -127.9 0.572 -129.9 0.552 -13.1
MAX2683
MAX2684
Table 1. MAX2683/MAX2684 RFIN Port S-Parameters (V
CC
= +5V, T
A
= +25°C)
(16 paginas)
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