MAX2023ETX+T Maxim Integrated Products, MAX2023ETX+T Datasheet - Page 10

• Manufacturer Part Number: MAX2023ETX+T
• Description: Modulator / Demodulator IC MOD/DEMOD HI DYN RNG
• Manufacturer: Maxim Integrated Products

Specifications of MAX2023ETX+T

• Package / Case: QFN-36
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

High-Dynamic-Range, Direct Up-/Downconversion
1500MHz to 2300MHz Quadrature Mod/Demod
The MAX5895 DAC has programmable gain and differ-
ential offset controls built in. These can be used to opti-
mize the LO leakage and sideband suppression of the
MAX2023 quadrature modulator.
The MAX2023 is an ideal modulator for a zero-IF (ZIF),
single-carrier GSM transmitter. The device’s wide dynamic
range enables a very efficient overall transmitter architec-
ture. Figure 2 illustrates the exceptionally simple complete
lineup for a high-performance GSM/EDGE transmitter.
The single-carrier GSM transmit lineup generates base-
band I and Q signals from a simple 12-bit dual DAC
such as the MAX5873. The DAC clock rate can be a
multiple of the GSM system clock rate of 13MHz. The
ground-referenced outputs of the dual DAC are filtered
by simple discrete element lowpass filters to attenuate
both the DAC images and the noise floor. The I and Q
baseband signals are then level shifted and amplified
by a MAX4395 quad operational amplifier, configured
as a differential input/output amplifier. This amplifier
can deliver a baseband power level of greater than
+15dBm to the MAX2023, enabling very high RF output
power levels. The MAX2023 will deliver up to +5dBm
for GSM vectors with full conformance to the required
system specifications with large margins. The excep-
tionally low phase noise of the MAX2023 allows the cir-
10
Figure 2. Complete Transmitter Lineup for GSM/EDGE DCS/PCS-Band Base Stations
Q
I
_______________________________________________________________________________________________
12
12
DUAL DAC
MAX5873
GSM Transmitter Applications
QUAD AMP
MAX4395
MAX2021/MAX2023
90°
0°
∑
cuit to meet the GSM system level noise requirements
with no additional RF filters required, greatly simplifying
the overall lineup.
The output of the MAX2023 drives a MAX2059 RF VGA,
which can deliver up to +15dBm of GSM carrier power
and includes a very flexible digitally controlled attenuator
with over 56dB of adjustment range. This accommodates
the full static and dynamic power-control requirements,
with extra range for lineup gain compensation.
The MAX2023 utilizes an internal passive mixer archi-
tecture that enables the device to possess an excep-
tionally low-output noise floor. With such architectures,
the total output noise is typically a power summation of
the theoretical thermal noise (kTB) and the noise contri-
bution from the on-chip LO buffer circuitry. As demon-
strated in the Typical Operating Characteristics , the
MAX2023’s output noise approaches the thermal limit
of -174dBm/Hz for lower output power levels. As the
output power increases, the noise level tracks the noise
contribution from the LO buffer circuitry, which is
approximately -165dBc/Hz.
The I/Q input power levels and the insertion loss of the
device determine the RF output power level. The input
power is a function of the delivered input I and Q volt-
ages to the internal 50Ω termination. For simple sinu-
VCO + SYNTH
MAX9491
95MHz LO
45, 80,
31dB
OR
MAX2058/MAX2059
RF DIGITAL VGAs
INTO Rx CHAIN
(FEEDS BACK
FRONT-END)
LOOPBACK
17dB
OUT
OFF
Rx
CONTROL
LOGIC
SPI
SPI
31dB
RF Output
RFOUT