Datasheet

Maxim Integrated │ 20
MAX2022 High-Dynamic-Range, Direct Up/
Downconversion 1500MHz to 3000MHz
Quadrature Modulator/Demodulator
www.maximintegrated.com
RF Output
The MAX2022 utilizes an internal passive mixer architec-
ture.Thisenablesaverylownoisefloorof-173.2dBm/Hz
for low-level signals, below about -20dBm output power
level. For higher output level signals, the noise floor will
be determined by the internal LO noise level at approxi-
mately -162dBc/Hz.
The I/Q input power levels and the insertion loss of the
device will determine the RF output power level. The input
power is the function of the delivered input I and Q voltag-
estotheinternal50Ωtermination.Forsimplesinusoidal
basebandsignals,alevelof89mV
P-P
differential on the I
andtheQinputsresultsinaninputpowerlevelof-17dBm
deliveredtotheIandQinternal50Ωterminations.This
results in a -23.5dBm RF output power.
Generation of WCDMA Carriers
The MAX2022 quadrature modulator makes an ideal sig-
nal source for the generation of multiple WCDMA carriers.
The combination of high OIP3 and exceptionally low out-
put noise floor gives an unprecedented output dynamic
range. The output dynamic range allows the generation of
four WCDMA carriers in the UMTS band with a noise floor
sufficiently low to meet the 3GPP specification require-
ments with no additional RF filtering. This promotes an
extremely simple and efficient transmitter lineup. Figure 2
illustrates a complete transmitter lineup for a multicarrier
WCDMA transmitter in the UMTS band.
The MAX5895 dual interpolating-modulating DAC is
operated as a baseband signal generator. For genera-
tion of four carriers of WCDMA modulation, and digital
predistortion, an input data rate of 61.44 or 122.88Mbps
can be used. The DAC can then be programmed to
operate in x8 or x4 interpolation mode, resulting in a
491.52Msps output sample rate. The DAC will gener-
ate four carriers of WCDMA modulation with an ACLR
typicallygreaterthan77dBundertheseconditions.The
output power will be approximately -18dBm per carrier,
with a noise floor typically less than -144dBc/Hz.
The MAX5895 DAC has built-in gain and offset fine
adjustments. These are programmable by a 3-wire serial
logic interface. The gain adjustment can be used to adjust
the relative gains of the I and Q DAC outputs. This feature
can be used to improve the native sideband suppression
of the MAX2022 quadrature modulator. The gain adjust-
ment resolution of 0.01dB allows sideband nulling down
to approximately -60dB. The offset adjustment can simi-
larly be used to adjust the offset DC output of each I and
Q DAC. These offsets can then be used to improve the
native LO leakage of the MAX2022. The DAC resolution
of 4 LSBs will yield nulled LO leakage of typically less
than -50dBc relative to four-carrier output levels.
Figure 2. Complete Transmitter Lineup for a Multicarrier WCDMA in the UMTS Band
MAX5895
MAX2022
RF-MODULATOR
MAX2057
TX
OUTPUT
+12dB
L-C FILTER
I/Q GAIN AND
OFFSET ADJUST
I
I
Q
Q
∑
CLOCK
SYNTH