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Maxim > Design Support > Technical Documents > Application Notes > A/D and D/A Conversion/Sampling Circuits > APP 3559
Maxim > Design Support > Technical Documents > Application Notes > Basestations/Wireless Infrastructure > APP 3559
Maxim > Design Support > Technical Documents > Application Notes > High-Speed Signal Processing > APP 3559
Keywords: high performance,RF, modulator, heterodyne, transmitter, multi-carrier, direct conversion, IF,
CDMA2000, WCDMA, OFDM, OIP2, OIP3, noise floor, LO, ACLR, UMTS, Tx, digital-to-analog converter,
DAC, interpolation filter, cascade, reject mixer
APPLICATION NOTE 3559
High-Performance RF Modulator Enables Multi-
Carrier Communications Transmitters
Jun 20, 2005
Abstract: Cellular transmitters rely on high-performance RF modulators to maintain linearity and dynamic
range. With the growth of multi-carrier transmitters, RF modulators must maintain a low noise floor while
delivering good high-level performance, usually determined by second- and third-order intercept points.
The following article discusses these requirements and explains how the MAX2022 meets the
requirements for a typical four-carrier WCDMA transmitter architecture.
Overview
Today nearly all cellular base stations employ super heterodyne
architectures to transmit/receive RF signals. These architectures
require two or more up/down conversion stages, intermediate
filtering, and analog signal processing. Figure 1 shows a typical
dual-conversion, cellular-base-station transmit block diagram. Many
of these transmitters were implemented as single-carrier systems.
Multi-carrier transmitters replicate single-carrier transmitters multiple
times, thus introducing substantially more system hardware. To
reduce transmitter cost, many system designers are turning to multi-
carrier transmitters and direct-conversion RF architectures.
Figure 1. Typical super heterodyne transmit architecture.
The Challenges of a Multi-Carrier Architecture
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