Analog Devices ADRV9001 User Manual page 114

UG-1828
It is important that a suitable attenuator be chosen between the power amplifier output and the observation channel input. This is to
prevent Tx data from saturating the observation channel input. The following paragraph summarizes the external system requirement.
External system requirement: a suitable attenuator must be chosen between the power amplifier output and the observation channel
input to prevent Tx data from saturating the observation channel input. The LNA (or RF switch if no LNA presented externally) for the
loopback path should be switched off to avoid receiving signals from RF port.
System Considerations for Receiver Initial Calibrations
In this section, similarly, high level block diagrams are used to show the device configurations and external system requirements for
receiver initial calibrations. In all the diagrams, grayed-out lines and blocks are not active in the calibration. Blue blocks are related
calibrations. It should be noted that the ADRV9001 ARM performs each of the calibrations. It is tasked with configuring the ADRV9001
device as per the diagrams below, with respect to enabling/disabling paths, etc. No user input is required in this regard. However, it is
important that the user ensures that external system conditions are met, such as having the Rx input properly terminated for Rx
initialization calibrations.
Among 11 different Rx initial calibrations, RX_HPADC_RC, RX_HPADC_FLASH, RX_HPADC_DAC (not enabled) and RX_LPADC
calibration are performed in the analog domain and the corrections are applied to HP ADC or LP ADC (based on which one is utilized),
while all other Rx initial calibrations are performed in the digital domain. For RX_QEC_FIC and RX_QEC_TCAL, the calibration results
are applied in digital domain for correction. For RX_DCC, RX_RF_DC_OFFSET, RX_TIA_CUTOFF, RX_GROUP_DELAY and
RX_QEC_ILB_LO_DELAY, the calibration results are applied in the analog domain for correction. Figure 102 shows the high level block
diagram of system configurations for Rx initial calibrations. Note different calibration performs at different locations in the Rx datapath
which is simplified in Figure 102.
LNA SWITCH OFF
During receiver initial calibration, as shown in Figure 102, the data port is disabled to avoid sending data to baseband processor. This is
controlled by ADRV9001 ARM which requires no user interaction. Except for RX_RF_DC_OFFSET calibration, all other digital domain
calibration algorithms require injecting calibration tones generated internal by calibration PLL and injected internally at the Rx input.
For example, the RX_QEC_TCAL calibration routine sweeps a number of internally generated test tones across the desired frequency
band and then measures quadrature performance and calculates correction coefficients. Therefore, during Rx calibration, it is required to
not receiving any incoming signals from RF port which could interfere with the calibration tones. To ensure that, it is important to
isolate the device Rx input port from incoming signals by disabling LNA (or by switching off the external RF switch if no LNA presented
externally). This also prevents the calibrations tones from reaching antenna through RF coupling. 50Ω termination is needed to prevent
tone signals bouncing back from external LNA output and reaching Rx input confusing internal calibrations. The following paragraph
summarizes the external system requirement.
External system requirement: for optimal performance, and lower calibration duration, during Rx initial calibrations, the device Rx input
port should be isolated from incoming signals. For many Rx calibrations, the calibration tones will appear on the Rx pins, therefore, must
be prevented from reaching the antenna through the Rx port being properly terminated. This also prevents the calibrations tones from
reaching antenna through RF coupling. 50Ω termination is needed to prevent tone signals bouncing back from external LNA output and
reaching Rx input confusing internal calibrations.
Configure the Initial Calibrations Through TES
To achieve optimal performance, all initial calibrations should be enabled. However, the TES provides the capability to allow user to
disable some initial calibrations, mainly for debugging purpose. Table 45 summarizes a comparison for all initial calibrations in terms of
"User Override Capability", "Run at Boot", "Signal Utilized by Calibration", "External Termination Needed" and "Dependency". Some
initial calibrations need to be rerun after "LO changes more than a certain range (e.g. 100MHz) or divide by 2 boundary change". The
information is currently not available and will be provided in the future after characterization.
ADRV9001 Rx
0°
LNA
90°
CAL
PLL
HPADC_RC
HPADC_FLASH
LPADC
Figure 102. Receiver Initial Calibration System Configuration
LPF
HP
ADC
RX_QEC_FIC
LP
LO1
RX_QEC_TCAL
ADC
RX_RF_DC_OFFSET
LP
LO2
RX_TIA_CUTOFF
ADC
RX_GROUP_DELAY
RX_DCC
HP
RX_QEC_ILB_LO_DELAY
ADC
LPF
Rev. PrA | Page 114 of 253
Preliminary Technical Data
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