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DETAILED DESCRIPTION

GC5322 Introduction

Baseband Interface

Gain/Pilot Insertion/AntCal Insertion/Power Meter

Digital Upconverters (DUCs)

GC5322

SLWS208 – JANUARY 2008

The GC5322 is a flexible transmit sector processor that includes a digital upconverter (DUC) block, a crest factor

reduction (CFR) block, and a digital predistortion (DPD) block and its associated feedback chain. The GC5322

processes composite input bandwidths of up to 40 MHz and processes DPD expansion bandwidths of up to 140

MHz (actual performance may vary for signal bandwidths exceeding 23 MHz). By reducing both the

peak-to-average ratio (PAR) of the input signals using the CFR block and linearizing the power amplifier (PA)

using the DPD block, the GC5322 reduces the costs of multicarrier PAs (MCPA) for wireless infrastructure

applications. The GC5322 applies CFR and DPD while a separate microprocessor (a Texas Instruments

TMS320C6727 DSP) is used to optimize performance levels and maintain target PA performance levels.

By including the GC5322 in their system architecture, manufacturers of BTS equipment can realize significant

savings on power amplifier bill of materials (BOM) and overall operational costs due to the PA efficiency

improvement. The GC5322 meets multicarrier 3G performance standards (PCDE, composite EVM, and ACLR) at

PAR levels down to 6.5 dB and improves the ACLR, at the PA output, by 20 dB to 30 dB or more. The GC5322

integrates easily into the transmit signal chain between baseband processors such as the Texas Instruments

TMS320C64x™ DSP family and their high-performance data converters.

A typical GC5322 system application would include the following transmit-chain components:

• TMS320C6727 digital signal processor (DSP)

• DAC5682 16-bit, 1-GSPS DAC (transmit path)

• CDCM7005 clock generator

• TRF3761 integrated VCO/PLL synthesizer

• TRF3703 quadrature modulator

• ADS5517 11-bit 200-MSPS or ADS5444 13-bit, 250-MSPS ADC (feedback path)

• AMC7823 analog monitoring and control circuit with GPIO and SPI

The GC5322 BB interface block accepts baseband signals over an interleaved parallel interface at a data rate of

up to 93.3 MHz. The input interface supports up to 12 separate baseband carriers. The GC5322 DUC block can

be programmed in a wideband mode in which users are required do channelize the data using an external

processor.

Baseband gain can be applied on a per-carrier basis to accurately control the individual channel power through

the system. Also present is the functionality for adding pilot codes to the data stream for antenna calibration

applications. Independent programmable RMS power meters for up to 12 channels are also included in this block

of the device.

The GC5322 DUC block digitally upconverts, spectrally shapes and combines multiple channels into one

wideband, composite signal. It can support:

• Up to twelve cdma2000/TDSCDMA carriers

• Up to four 5-MHz W-CDMA (UMTS) carriers

• Up to two 10-MHz OFDMA (WiMAX/WiBRO) channels

• One 20-MHz OFDMA (WiMAX/WiBRO) channel

Or, with reduced DPD expansion bandwidth:

• Up to four 10-MHz OFDMA (WiMAX/WiBRO) channels

• Up to two 20-MHz OFDMA channels

• One 40-MHz OFDMA channel

Copyright © 2008, Texas Instruments Incorporated

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