GC5330IZEV Datasheet, PDF (19/49 Pages) Texas Instruments – Wideband Transmit-Receive Digital Signal Processors

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GC5330
GC5337
SLWS226 B – DECEMBER 2010 – REVISED JANUARY 2011
DPD – Envelope Tracking (ET) Mode
The ET block provides a 10-, 12-, or 14-bit real digital word, at a rate up to 155 MSPS, that is proportional to the
peak envelope signal of the composite TX stream either before or after the DPD function. The ET block includes
fixed and fractional delay adjustments and a LUT to provide nonlinear shaping to the ET waveform. The GC533x
can provide one or two ET outputs along with the corresponding one or two TX signal stream outputs. The ET
outputs use one of the LVDS DAC ports and have two interface format modes:
a. One or two antenna streams. One antenna stream per port, with interleaved MSB half-word and LSB
half-word. The port can be configured as 7-, 6-, or 5-bit DDR data (see Table 14 and Figure 18), plus clock
(maximum clock rate of 155 MHz in this mode). In all three cases, the 16-bit internal data is rounded to the
specified 14, 12, or 10 bits. Format on the DDR data port for the three cases is:
14-bit: [13:7], then [6:0]
12-bit: [11:6], then [5:0]
10-bit: [9:5], then [4:0]
b. One antenna stream only. One antenna stream per port. The port can be configured as 14-, 12-, or 10-bit
SDR data (see Figure 18), plus clock (maximum clock rate of 155 MHz in this mode). In all three cases, the
16-bit internal data is rounded to the specified 14, 12, or 10 bits.
Note that clock out may have a few hundred ps of jitter and is not suitable for directly driving the ET modulator
DAC. The clock for the ET modulator DAC should come directly from a TI CDC clock chip, which is already on
the board to provide clock sources.
TX IF Sub-Chip
The TX IF sub-chip includes a bulk upconverter (BUC), four IF mixer/NCO blocks, and TX stream MUX and
SUM.
The BUC block has interpolations of 1×, 1.5×, 2×, 3×, and 4×. In the DPD high-band width mode, the 2×
interpolation from the BUC is routed to the DPD input. In the high-bandwidth mode, BUC interpolation is not used
after DPD. In the DPD high-performance mode, BUC interpolation is dependent on the configuration.
There are four parallel NCO/MIX blocks to allow frequency translation of each composite TX stream. The NCO is
48 bits and is referenced to the TX output rate. The NCO/MIX block can be used in either HP or HB modes;
however, using the mixer reduces the DPD expansion bandwidth by the amount of frequency translation.
The TX stream MUX and SUM block allows summing of TX streams to create composite TX streams.
TX DAC Formatter
The DAC output consists of two 20-pair LVDS blocks that can be configured by the DAC formatter block for
several TI DACs and system configurations. The formatter can support up to 8 DACs for 4 TX streams in
complex mode. The DAC formatter block supports the TI DAC5682, DAC328x, and DAC348x families. Table 5
illustrates the pin connections the different DAC and envelope [ET] modulator types.
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