Analog Devices ADRV9001 User Manual page 146

UG-1828
As shown in Figure 140, TX_LB_PD, TX_QEC, TX_LO_LEAKAGE, TX_DCC, and TX_ATTEN_DELAY use the ILB for calibrations.
TX_LO_LEAKAGE and TX_QEC calculate the initial correction parameters. TX_LB_PD provides a measurement of the loop back path
delay for TX_LO_LEAKAGE and TX_QEC algorithms. Both TX_LO_LEAKAGE and TX_QEC calibrations sweep through a series of
attenuation values, creating a table of initial calibration values. Then during operation and upon application of a new transmitter
attenuation setting, the corresponding QEC and LO_LEAKAGE correction values are applied to the transmitter channel by the
ADRV9001 ARM. TX_DCC estimates the duty cycle error in the digital domain but applies the correction in the analog domain.
TX_ATTEN_DELAY measures the delay between the transmitter digital attenuation block and transmitter analog attenuation block and
it uses the ILB for delay observation and estimation.
During all these calibrations, similarly, the power amplifier connected to the device output should be switched off and 50 Ω termination is
needed. In addition, it is important to switch off the LNA (or RF switch if no LNA presented externally) external to the receiver datapath
to avoid the interference from the RF port into Rx input used for data traffic. The following paragraph summarizes the external system
requirement.
External system requirement: for transmitter initial calibrations using ILB, the power amplifier in the transmitter path should be powered off
during these calibrations. When the power amplifier is disabled, the load seen at the transmitter output should be 50 Ω. The LNA (or RF switch if
no LNA presented externally) for the loopback path should also be switched off to avoid receiving signals from RF port.
Initial Transmitter Calibration Utilizing Internal Signal Generation and ELB
Although not currently supported, it is also possible to perform some transmitter initial calibrations using ELB. As mentioned in the
Receiver/Observation Receiver Signal Chain section, using ELB1 for initial calibrations provides the advantage of observing common
mode voltage. When ELB1 is used, it has the same external system requirements as using ILB. Figure 141 shows the high level block
diagram of initial transmit calibrations using internal signal generation and ELB1.
DUPLEXER
(TDD, FDD)
COUPLER
Figure 141. Transmitter Initial Calibration System Configuration with Signal Generation and External Loop Back Type 1
For TX_LO_LEAKAGE, another option is to use ELB2. Figure 142 shows the high level block diagram of system configurations for
TX_LO_LEAKAGE initial calibrations using ELB2 (Note TX_LB_PD initial calibration using ELB2 is required for TX_LO_LEAKAGE).
LNA SWITCH OFF
DUPLEXER
(TDD, FDD)
COUPLER
Figure 142. Tx Initial Calibration System Configuration with Signal Generation and External Loop Back Type 2
ADRV9001
LNA SWITCH OFF
LNA
ELB1
PA
PA SWITCH OFF
ADRV9001
LNA
ATTENUATOR
ELB2
PA
PA SWITCH ON
LPF
HP
ADC
LP
LO1
0°
ADC
90°
LP
LO2
ADC
HP
ADC
LPF
LPF
DAC
LO1
0°
90°
LO2
DAC
LPF
LPF
HP
ADC
LP
LO1
0°
ADC
90°
LP
LO2
ADC
HP
ADC
LPF
LPF
DAC
LO1
0°
90°
LO2
DAC
LPF
Rev. PrC | Page 146 of 338
Preliminary Technical Data
To BBP
From BBP
SIGNAL
GENERATOR
To BBP
From BBP
SIGNAL
GENERATOR