GC5322 Datasheet, PDF (5/6 Pages) Texas Instruments – GC5322 Wideband Digital Predistortion Transmit Processor

GC5322
www.ti.com
SLWS208 – JANUARY 2008
Microprocessor Interface (MPU)
The MPU interface is designed to interface with external memory interface (EMIF) ports on TI DSPs operating in
asynchronous mode. It consists of a 16-bit bidirectional data bus, a 10-bit address bus, and RDB, WRB, OEB,
and CEB control signals. The interface fully supports TI 'C55x™, 'C64x™ DSPs and, with minimal effort,
supports the low-cost 'C6727 floating-point DSP.
Smart Capture Buffers (SCB)
The GC5322 has two capture buffers, each 4096 complex words deep, which are periodically read by the
external coefficient update controller (DSP) in order to optimize the DPD coefficients. The first capture buffer can
be used to capture:
• The output of the Farrow resampler; this is also called the reference signal.
• The feedback output; this represents the waveform as seen by the PA.
• The error output
• Testbus(31:16)
The second capture buffer can be used to provide:
• The output of the Farrow resampler; this is also called the reference signal.
• The feedback output; this represents the waveform as seen by the PA.
• The error output
• Testbus(15:0)
The reference and feedback buffers are time-aligned by the GC5322, because there may be a delay of tens or
even hundreds of samples between the transmitted signal and the feedback signal from the PA output. The
capture controller can trigger a capture on several different metrics, including an above-threshold peak count or
an average signal power value.
Input and Output Syncs
The GC5322 features multiple-user programmable input syncs. These are typically used as trigger mechanisms
to activate features within the device. These triggers can be provided internally or through externally provided
inputs. The input syncs can be used to trigger:
• Power measurements
• DUC channel delay, dither, and tuner alignment
• Initializing/loading the DUC, feedback, equalizer, LUTs, etc.
• Flush out data within the processing blocks of the device
• Feedback path tuner alignment
• Capturing and sourcing of data through SCBs
Programmable Power Meters
There are three power meter locations/functions within the GC5322. The first is a channel RMS power meter.
The second power meter is located at the output of the CFR block, and the final power detector is similar to the
CFR output power detector and is located at the Farrow resampler output. This power meter can measure RMS
power integrated up to a million samples at the DPD sample rate.
Related Material and Documents
• GC5322 Quick Start Guide
• Application Note: GC5322 Configuration and Performance for a UMTS (W-CDMA) BTS
• Application Note: GC5322 Configuration and Performance for an OFDMA (802.16e) BTS
• Application Note: GC5322 Configuration and Performance for a TD-SCDMA BTS
• GC5322 Architecture Data Sheet (DUC, CFR, FR, DPD, and BUC)
Contact Texas Instruments for projected availability of listed documents.
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): GC5322
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