MAX2022EVKIT Maxim Integrated Products, MAX2022EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX2022EVKIT
• Description: EVAL KIT FOR MAX2022
• Manufacturer: Maxim Integrated Products
• Type: Modulator, Demodulatorr

Specifications of MAX2022EVKIT

• Frequency: 1.5GHz ~ 2.5GHz
• For Use With/related Products: MAX2022
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The desired sideband power level should be approxi-
mately -23.5dBm (-20.5dBm output power including
3dB pad loss). Phase and amplitude differences at the
I and Q inputs result in degradation of the sideband
suppression. Note that the spectrum analyzer’s uncali-
brated absolute magnitude accuracy is typically no
better than ±1dB.
The MAX2022 is designed for upconverting (downcon-
verting) to (from) a 1500MHz to 2500MHz RF from (to)
baseband. Applications include single- and multicarrier
1800MHz to 2200MHz UMTS/WCDMA, cdma2000,
DCS/PCS, and WiMAX base stations. Direct upconver-
sion (downconversion) architectures are advantageous
since they significantly reduce transmitter (receiver)
cost, part count, and power consumption compared to
traditional heterodyne conversion systems.
The MAX2022 integrates internal baluns, an LO buffer,
a phase splitter, two LO driver amplifiers, two matched
double-balanced passive mixers, and a wideband
quadrature combiner. Precision matching between the
in-phase and quadrature channels, and highly linear
mixers achieve excellent dynamic range, ACLR, 1dB
compression point, along with LO and sideband sup-
pression, making it ideal for 4-carrier W-CDMA/UMTS
operation.
The MAX2022 EV kit circuit allows for thorough analysis
and a simple design-in.
The MAX2022 has several RF processing stages that
use the various V
decoupling, off-chip interaction between them may
degrade gain, linearity, carrier suppression, and output
power. Proper voltage-supply bypassing is essential for
high-frequency circuit stability.
C1, C6, C7, C10, and C13 are 22pF supply-decoupling
capacitors used to filter high-frequency noise. C2, C5,
C8, C11, and C12 are larger 0.1µF capacitors used for
filtering lower-frequency noise on the supply.
The MAX2022 has internal baluns at the RF output and
LO input. These inputs have almost 0Ω resistance at
DC, and so DC-blocking capacitors C3 and C9 are
used to prevent any external bias from being shunted
directly to ground.
Supply-Decoupling Capacitors
_______________________________________________________________________________________
CC
Detailed Description
pins. While they have on-chip
DC-Blocking Capacitors
MAX2022 Evaluation Kit
The bias current for the integrated LO buffer is set with
resistor R1 (432Ω ±1%). Resistors R2 (562Ω ±1%) and
R3 (301Ω ±1%) set the bias currents for the LO driver
amplifiers. Increasing the value of R1, R2, and R3
reduces the current, but the device will operate at
reduced performance levels. Doubling the values of R1,
R2, and R3 reduces the total current to approximately
166mA, but the OIP3 degrades by approximately 4.5dB.
When desired, a common-mode voltage can be inject-
ed onto the BB input lines through TP3 on the EV kit. To
enable this feature, the proper value of resistors R5, R6,
R9, R10, and R12–R15 need to be installed. Resistors
R15/R14 and R13/R12 form voltage-dividers, while R5,
R6, R9, and R10 are large-value bias injection resistors.
See Figure 3 for EV kit schematic details.
LO leakage at the RF port can be nulled to a level less
than -80dBm by introducing DC offsets at the I and Q
ports. However, this null at the RF port can be compro-
mised by an improperly terminated I/Q IF interface.
Care must be taken to match the I/Q ports to the driving
DAC circuitry. Without matching, the LO’s second-order
(2f
port where it can mix with the internal LO signal to pro-
duce additional LO leakage at the RF output. This leak-
age effectively counteracts against the LO nulling. In
addition, the LO signal reflected at the I/Q IF port pro-
duces a residual DC term that can disturb the nulling
condition.
As shown in Figure 1, providing an RC termination on
each of the I+, I-, Q+, Q- ports reduces the amount of
LO leakage present at the RF port under varying temp-
erature, LO frequency, and baseband drive conditions.
Note that the resistor value is chosen to be 100Ω with a
corner frequency 1 / (2πRC) selected to adequately filter
the f
of the baseband response at the highest baseband
frequency. The common-mode f
I+/I- and Q+/Q- effectively see the RC networks and
thus become terminated in 50Ω (R/2). The RC network
provides a path for absorbing the 2f
while the inductor provides high impedance at f
2f
LO
LO
LO
to help the diplexing process.
) term may leak back into the modulator’s I/Q input
and 2f
LO
leakage, yet not affecting the flatness
LO
External Diplexer
LO
and 2f
and f
LO
LO
LO Bias
signals at
IF Bias
leakage,
LO
and
3