The user can refer to the “ Rx/ORx TIA Initial Calibration ”section in ADRV9026 user guide to get the fundamental working theory of Rx/ORx TIA calibration.The Rx/ORx TIA calibration is used to calibrate the corner frequency of the analog baseband TIA filter in the Rx/ORx signal path. AUX PLL will work as the signal source to generate the cal tone.If user find some issues related to TIA initial cal, they can follow below instructions to identify the root cause:1. The user need to guarantee there are no interference signal from outside chip presented on the input port when do the calibrations. Interference signal may cause the calibration fails. To identify if it is the root cause, the user can increase the Rx input port isolation by power down the LNA and external Rx gain block, or terminate the ADRV9026 input port with 50ohm load.2. The user can set different channel mask when call the API function (adi_adrv9025_InitCalsRun) to run the Rx TIA calibration. By this way they can identify if the calibration always fail on one dedicated channel or randomly on different channels.3. Use GPINT to monitor if Aux PLL has problem during calibration. (If PLL has problem during TIA cal it is better to re look at power supply circuit). Below is an instruction on how to setup GPINT to monitor Aux PLL lock status during TIA cal.
Refer to the “ GENERAL-PURPOSE INTERRUPT ”section in ADRV9026 user guide to set up the GPINT1/GPINT2 and monitor the AUX PLL lock status during the Rx/ORx TIA calibration procedure. In the “ GP_INTERRUPT Bitmask Description “ table. Bit[D45] is the AUX PLL Unlock indicator. Set this bit [D45] as zero and the other bits as one will set up the general purpose interrupt pin to monitor the AUX PLL lock/unlock event only. When the general purpose interrupt pin is low indicate the AUX PLL locked. if asserted, indicate that a PLL has unlocked . During Rx TIA calibration procedure . To each Rx channel. If use the GPINT1/GPINT2 to monitor the AUX PLL lock status with oscilloscope. The user can see four time GPINT1/GPIN2 go high event due to the AUX PLL switch the RF frequency. The GPINT1/GPIN2 high duration is around 20ms normally. Below is the Python code on ADI EVB platform to set up the AUX PLL lock status monitor with GPINT1. Other GPINT1 interruption source is masked.
#GpInt0 Monitor AUX PLL Lock Status, D45 set as zeromaskArray.gpInt0Mask = 0xFFFFDFFFFFFFFFFFlink.platform.board.Adrv9010Device.Gpio.GpIntMaskSet(1,maskArray)
4. Check the voltage of 4.7uF bypass capacitor which is connected to VAUXVCO_1P0 power supply pin(B11). It should be 1.0V when using internal LDO mode.5. The user can call the API function adi_adrv9025_ArmMemDump in adi_adrv9025_utilities.c file to dump the ARM memory for further analysis when the initialization calibration fails.