Preliminary Technical Data UG-1828
Rev. PrC | Page 199 of 338
ADRV9001 DPD SUPPORTED WAVEFORMS
The integrated DPD supports NB waveforms such as TETRA. Note some NB standard waveforms such as Direct Modulation types with
constant envelope do not require DPD. The different modes of operation for TETRA are listed in Table 79. The integrated DPD supports
all TETRA 1 and 2 modes.
Table 79. Supported NB Standards and Associated Operational Parameters
TETRA1 25 DQPSK 1 3.1
TETRA2 25 4 QAM 8 9.6
TETRA2 25 16 QAM 8 9.5
TETRA2 25 64 QAM 8 10.3
TETRA2 50 4 QAM 16 10.2
TETRA2 50 16 QAM 16 10.3
TETRA2 50 64 QAM 16 10
TETRA2 100 64 QAM 32 11.2
TETRA2 150 64 QAM 48 10.8
Besides that, the integrated DPD also supports some WB LTE and LTE-like waveforms with their associated operational parameters.
Other WB waveforms can be supported if the power amplifier behavior fits the designed hardwired amplifier model, as well as the
sampling rates and transceiver bandwidth.
The WB LTE standards supported and their associated operation parameters are summarized in Table 80.
Table 80. Supported WB Standards and Associated Operational Parameters
LTE Bandwidth (MHz) Number of Carriers PAR (dB) Before CFR
1.4 Multicarrier ~11
3 Multicarrier ~11
5 Multicarrier ~11
15 Multicarrier ~11
20 Multicarrier ~11
In theory, DPD can support any profile with a RF signal bandwidth less than 1/5 of the ADRV9001 system frequency. For example, if the
ADRV9001 has a system frequency of 184.32MHz, DPD can support a signal bandwidth if it is less than 36.864MHz.
As shown in Table 79 and Table 80, multicarrier TETRA2 has a Peak-to-Average Ratio (PAR) between 9.6 dB to 11.2 dB and multi-carrier
LTE signal typically has a PAR of about 11dB. To achieve higher PA efficiency and DPD algorithm stability, a waveform with a large PAR
is expected to have crest factor reduction (CFR) performed in baseband processor before DPD operation. It is important that CFR is
applied to a multicarrier signal before transmission since it keeps the average power higher while maintaining the same peak back off in
the digital transmit data. Also, CFR suppresses large peaks to below a preset threshold therefore eliminating occasional large peaks that
could make DPD unstable if the peak is beyond the compression threshold limit of the PA. For example, an LTE signal has a PAR of about
11 dB and the PAR can be reduced by CFR to be about 7 dB by trading off EVM. Note it is the responsibility of baseband processor to
perform CFR with an appropriate tradeoff between PAR reduction and EVM degradation before sending the transmit data to ADRV9001.
It should be also noted that additional EVM degradation caused by the integrated DPD is negligible compared to the degradation caused
by CFR.
DPD WITH FREQUENCY HOPPING (FH)
ADRV9001 also supports DPD operation during frequency hopping (FH). In this case, user could identify multiple frequency regions and
for any LO frequency in one region, the same DPD solution is applied. ADRV9001 allows a maximum of 8 frequency regions. User could
define each region by specifying the lower bound and upper bound LO frequencies ([lower bound, upper bound)) for up to 7 regions and
the rest LO frequencies are in the 8
th
region.
ADRV9001 DPD PERFORMANCE
The integrated DPD algorithm has been tested using both MOS type and GaN type of PAs. As an example, Figure 185 and Figure 186
shows the AM-AM and AM-PM performance of the raw transmit signal input versus the MOS type of PA output before and after DPD
without FH. The test waveform is TETRA1. From Figure 186, it can be seen clearly that the PA nonlinearity is successfully corrected by
the integrated DPD.
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