Auxiliary Synthesizer; External Lo - Analog Devices ADRV9001 User Manual

Reference Manual ADRV9001
SYNTHESIZER CONFIGURATION AND LO OPERATION
Figure 95. LO Switching Network
Figure 96. LO Switching Network (Receiver Channels Configured as Observation Receivers for Transmitter Channels)
Note that depending on the application, select the best phase noise or best-power saving options for better optimization.This changes the
frequency the internal VCO operates at to optimize for phase noise or power consumption. The option of best phase noise only works
for LO frequency under 1 GHz. The RF LO power consumption has three configurable options (Low, Medium High), which balance the power
consumption and RF LO phase noise. This option changes some of the analog DC biases to reduce the VCO voltage swing, and thus the
power consumption. High power means low LO phase noise, and vice versa.
The ADRV9001 provides two modes of retuning the PLL: the normal mode and fast mode. In terms of phase noise performance, there is
no difference between the fast and normal modes. However, the normal mode tracks temperature over time while the fast mode does not.
Therefore, the fast mode takes less time to complete retuning.
The frequency step size of the RF PLLs is given by the following equation:
f_step,max = DEV_CLK / ( (2^23-15) * RfLogenDivider ), where RfLogenDivider can be retreived from the adi_adrv9001_Ra-
(1)
dio_RfLogenDivider_Get() API.

AUXILIARY SYNTHESIZER

An integrated auxiliary synthesizer generates the signals necessary to calibrate the device. This synthesizer uses a single core VCO. The
reference frequency for the auxiliary synthesizer is scaled from the device clock through the reference clock generation system. The output
signal is connected to a switching network and injected into the various circuits to calibrate filter bandwidth corners or into the receive
signal chain as an offset LO. Calibrations are executed during the initialization sequence at start-up. There should be no signal present at
the receiver/observation receiver input during tone calibration time. Calibrations are fully autonomous. During the calibration, the auxiliary
synthesizer is controlled solely by the internal ARM microprocessor and does not require any user interactions. The auxiliary LO signal is also
available as an LO source for the observation receiver mixers.

EXTERNAL LO

The device is provisioned with two external LO ports. These ports are available as a pair of balls and are configured to be the input for external
LO signals.
The external LO can receive a signal between 60 MHz and 12 GHz through a matched differential impedance of 100 Ω and delivers a
programmable signal between 30 MHz and 6 GHz as the LO for transmitters and receivers in the device. Maintain the amplitude between ±6
dBm. For more information, see the External LO Port Impedance Matching Network section..
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