Analog Devices ADRV9002 User Manual

UG-1828 Preliminary Technical Data
Rev. PrC | Page 198 of 338
Figure 183. High Level Block Diagram of DPD Algorithm
In the ADRV9001 device, DPD is considered as one of the transmitter tracking calibrations. It is a real-time signal processing with
iterative updates to account for hardware variations such as temperature and power level changes. Similar to some other transmitter
tracking calibrations, it requires a loopback path from the transmitter to the observation receiver (ORx) to perform the calibration. In this
case, an external loop back path (ELB) type 2 is required (please refer to the Receiver/Observation Receiver Signal Chain section for more
details about the loopback paths), in which, the transmitter output signal after PA is looped back to the ORx as shown in Figure 184. The
user must make sure this path is established before enabling the integrated DPD. In FDD applications where only one Rx is used or in the
TDD applications during transmit time slots, unused receiver path can be used to perform DPD calibration as well as some other
transmitter tracking calibrations. Please refer to ADRV9001 Example Use Cases section for more details.
Figure 184. High level Block Diagram of ADRV9001 DPD Implementation
Similar to what is shown in Figure 183, ADRV9001 DPD includes 2 major components, a “DPD Actuator” and a “Coefficients Calculation
Engine”. The “Coefficients Calculation Engine” computes the DPD coefficients periodically and then updates the “DPD Actuator” for
real-time pre-distortion of the transmit signal. The pre-distortion coefficients are associated with polynomial terms defined by the PA
model. In order to meet the real-time processing requirement, polynomial terms that are associated with a common time-delay input data
are pre-computed and stored into Look-up Tables (LUT) in the “DPD Actuator”. In the device, without frequency hopping, 2 LUTs are
used for all waveforms, one is currently being active for performing pre-distortion while the other one is being updated at the background
to track the changes and replace the current LUT when ready, resulting in seamless transmit operation. “DPD Actuator” also includes a
functionality to perform the calculation of the amplitude of the input signal, which is used to search the LUT. The outputs of the LUT are
then multiplied with different time delayed input data according to the configured DPD model and combined to form the final pre-
distorted transmit data.
DATA, d(
t
) INPUT, x(
t
)
OUTPUT, y(
t
)
FREQUENCY
MAGNITUDE
MAGNITUDE
FREQUENCY
MAGNITUDE
FREQUENCY
OUTPUT
INPUT
OUTPUT
OUTPUT
INPUT
INPUT
COMPRESSION
PREDISTORTOR PA
DPD
COEFFICIENTS
COMPUTAION
24159-141
DPD
ACTUATOR
DPD
LO
SYNTHESIZER
BALUN
POWER
AMPLIFIER
ELB TYPE 2
DIRECTIONAL
COUPLER
DUPLEXER
ANTENNA
DAC
COEFFICIENTS
CALCULATION
ENGINE
DAC
Tx ANALOG FRONT END
ADRV9001
Tx DATA
+
LO
SYNTHESIZER
BALUN
ADC
ADC
ORx ANALOG FRONT END
24159-142

Analog Devices ADRV9002 Specifications

General

Brand	Analog Devices
Model	ADRV9002
Category	Transceiver
Language	English