Preliminary Technical Data UG-1828
Rev. PrC | Page 27 of 338
Table 9. Constrains and Limitations in TDD Type Repeater Application with Baseband Processor Analyzing Traffic Data
Functionality Constrains and Limitations
In TDD type Repeater application, ADRV9001 can use its internal LO to generate RF LO1 for both uplink and downlink.
It is also possible to use external LO inputs in this mode of operation. External LO1 operating at 2× RF LO can be used
for both uplink and downlink.
RF Front End For LO generation, the ADRV9001 uses internal VCO that generates square wave type signal. A square wave LO would
produce harmonics. For example:
depending of RF matching used on the RF ports user 2nd LO harmonic can be as high as −50 dBc and 3rd harmonic
can be as high as −9 dBc. Therefore, the RF filtering on the Rx and Tx path must ensure that signals at the LO harmonic
frequencies (up to 9th in some cases) are not affecting overall system performance.
DPD The DPD functionality can be used in the 2R2T TDD mode. Maximum channel bandwidth that DPD can support is
limited by ADRV9001 RF bandwidth divided by 3 or by 5. The DPD operation can be performed by ADRV9001 or ORx
data can be sent to baseband processor via Rx data port during Tx operation. Rx path used during DPD operation to
perform Tx observation is also used by the Tx tracking calibrations. In case of external DPD, user must ensure that
access to the Rx path during Tx slots is time-shared between DPD operation and Tx calibrations.
Calibrations During Rx initialization sequence user must ensure that there are no signals present at the Rx input (external LNA
should be disabled) and appropriate termination should be present at LNA output to avoid reflections of Rx
calibration tones. The maximum input signal amplitude must not exceed −82 dBm/MHz for wideband modes, TBD
dBm/MHz for narrowband modes. During Tx initialization sequence the user must ensure that the power amplifier is
powered down to avoid unwanted emission of Tx calibration tones at the antenna.
ADRV9001 must access Rx datapath during Tx time slots for Tx tracking calibration to operate. If user use Tx
observation path with DPD functionality performed by baseband processor then access to the Rx datapath during Tx
slots must be time-shared between DPD operation and Tx calibrations.
AGPIOs Analog GPIOs (operating at 1.8 V level) can be used as read or write digital levels of in the end user system. AGPIOs
can be used to control states of external components or read back digital logic levels from external components.
DGPIOs Digital GPIOs can be used to perform real-time monitoring of states of internal ADRV9001 blocks. Digital GPIOs
operating as inputs can allow user to control Rx gain, Tx attenuation, AGC operation and other elements of ADRV9001
TRx. Depending on the ADRV9001 operation up to 4 GPIOs may be used by data port interface.
AuxADC AuxADC can be used to monitor analog voltage (for example, temperature sensor). Maximum AuxADC input voltage
must not exceed 0.9 V.
AuxDAC AuxDAC can be used to control the VCXO responsible for generating the ADRV9001 device clock, generate pre-
configured ramp up/down signal that can be used to control power amplifier bias, control any circuitry that requires
analog control voltage up to 1.8 V.
DEV_CLK_OUT ADRV9001 provides divided down version of DEV_CLK reference clock input signal on the DEV_CLK_OUT output. This
output is intended to provide reference clock signal to the digital components in the overall system. This output can
be configured to be active after power up and before ADRV9001 configuration stage.
Multichip Sync If there is no need for multichip synchronization, the ADRV9001 can be initialized using API functions only.
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