General Description
The MAX2021 low-noise, high-linearity, direct upconversion/downconversion quadrature modulator/demodulator is designed for RFID handheld and portal readers, as well as single and multicarrier 650MHz to 1200MHz GSM/EDGE, cdma2000®, WCDMA, and iDEN® base-station applications. Direct conversion architectures are advantageous since they significantly reduce transmitter or receiver cost, part count, and power consumption as compared to traditional IF-based double conversion systems.
In addition to offering excellent linearity and noise performance, the MAX2021 also yields a high level of component integration. This device includes two matched passive mixers for modulating or demodulating in-phase and quadrature signals, two LO mixer amplifier drivers, and an LO quadrature splitter. On-chip baluns are also integrated to allow for single-ended RF and LO connections. As an added feature, the baseband inputs have been matched to allow for direct interfacing to the transmit DAC, thereby eliminating the need for costly I/Q buffer amplifiers.
The MAX2021 operates from a single +5V supply. It is available in a compact 36-pin TQFN package (6mm x 6mm) with an exposed pad. Electrical performance is guaranteed over the extended -40°C to +85°C temper ature range.

Features
♦ 650MHz to 1200MHz RF Frequency Range
♦ Scalable Power: External Current-Setting
   Resistors Provide Option for Operating Device in
   Reduced-Power/Reduced-Performance Mode
♦ 36-Pin, 6mm x 6mm TQFN Provides High Isolation in a Small Package

Modulator Operation:
♦ Meets 4-Carrier WCDMA 65dBc ACLR
♦ +21dBm Typical OIP3
♦ +58dBm Typical OIP2
♦ +16.7dBm Typical OP1dB
♦ -32dBm Typical LO Leakage
♦ 43.5dBc Typical Sideband Suppression
♦ -174dBm/Hz Output Noise Density
♦ DC to 550MHz Baseband Input Allows a Direct Launch DAC Interface, Eliminating the Need for Costly I/Q Buffer Amplifiers
♦ DC-Coupled Input Allows Ability for Customer Offset Voltage Control

Demodulator Operation:
♦ +35.2dBm Typical IIP3
♦ +76dBm Typical IIP2
♦ > 30dBm IP1dB
♦ 9.2dB Typical Conversion Loss
♦ 9.3dB Typical NF
♦ 0.06dB Typical I/Q Gain Imbalance
♦ 0.15° I/Q Typical Phase Imbalance

Applications
   RFID Handheld and Portal Readers
   Single and Multicarrier WCDMA 850 Base Stations
   Single and Multicarrier cdmaOne™ and cdma2000 Base Stations
   GSM 850/GSM 900 EDGE Base Stations
   Predistortion Transmitters and Receivers
   WiMAX Transmitters and Receivers
   Fixed Broadband Wireless Access
   Military Systems
   Microwave Links
   Digital and Spread-Spectrum Communication Systems
   Video-on-Demand (VOD) and DOCSIS Compliant Edge QAM Modulation
   Cable Modem Termination Systems (CMTS)