Analog Devices ADRV9029 User Manual
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Analog Devices ADRV9029 User Manual

Analog Devices ADRV9029 User Manual

Transceiver dpd, clgc and cfr
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ADRV9029

SCOPE

This user guide is the preliminary documentation to explain ADRV9029's DPD, CLGC and CFR capability. This document is going to
be merged to ADRV9029 user guide. Please refer to ADRV9029 user guide once available thru ADI website.
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
ADRV9029
www.analog.com
Preliminary Technical Data
Transceiver DPD, CLGC and CFR User Guide
Rev. PrA | Page 1 of 82
DPD, CLGC and CFR User
Guide

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  • Page 1: Scope

    Transceiver DPD, CLGC and CFR User Guide SCOPE This user guide is the preliminary documentation to explain ADRV9029’s DPD, CLGC and CFR capability. This document is going to be merged to ADRV9029 user guide. Please refer to ADRV9029 user guide once available thru ADI website.

  • Page 2: Table Of Contents

    Preliminary Technical Data TABLE OF CONTENTS Scope ......................1 CFR Algorithm Overview .............. 43 Digital Pre-Distortion ................3 Overview of Blocks used in CFR ..........44 Digital Front-End System Level Overview ........ 3 API Software Integration ............... 45 DPD Introduction and Principle of Operation ......4 Typical Procedure to set up CFR Using the GUI ....

  • Page 3: Digital Pre-Distortion

    ACTUATOR CLGC Loop Gain Ctrl DPD and CLGC data capture and computation ORx atten BBIC ORx Obs PFIR Buffer Optional) DFE Signal Processing Figure 1. ADRV9029 Signal Chain with DFE Processing Blocks Highlighted Rev. PrA | Page 3 of 82...

  • Page 4: Dpd Introduction And Principle Of Operation

    Preliminary Technical Data DPD INTRODUCTION AND PRINCIPLE OF OPERATION DPD is a technique for improving the linearity of a non-linear system such as a power amplifier by introducing precise anti- distortion into the input waveform that compensates for the PA’s in-band nonlinear products. DPD works on the principle of pre- distorting the transmit data in the digital domain to cancel the distortion caused by PA compression in the analog domain.

  • Page 5: Transceiver Dpd Overview

    The inverse PA model is applied on the interpolated digital baseband samples through DPD actuator hardware. A dedicated embedded ARM processor (ARM-D) is used for computation of the GMP coefficients. ADRV9029 DPD DPD Actuator Data From...
  • Page 6 Preliminary Technical Data Figure 5. ADRV9029 DPD Actuator Functional Diagram There are two Half Band filters that could be enabled based on the input data rate and the desired DPD actuator rate. The half DPD Half Band Filters band filters have two important characteristics: the passband and stopband ripples are the same; and the passband-edge and stopband-edge frequencies are equidistant from the half band frequency Fs/4.

  • Page 7: Dpd Algorithm Overview

    Figure 7. Response for Both Half Band 1 and 2 Enabled (x4): 41% of Fs DPD ALGORITHM OVERVIEW The ADRV9029 DPD algorithm supports both indirect learning and direct learning DPD mechanisms for extracting DPD model coefficients. The details of direct and indirect DPD learning mechanisms are provided in the following sections.
  • Page 8 Preliminary Technical Data The mathematical representation of the DPD coefficient estimation is shown in Figure 9. The DPD engine observes N samples of PA input samples (X) and PA output samples (Y), and computes M-coefficients (c) corresponding to the inverse PA function F(x). F(x) f1(x1) f2(x1)
  • Page 9 Preliminary Technical Data Figure 11. DPD Direct Learning Coefficient Computation The direct learning outcome is an iterative solution, where the current coefficients are based on memory of previously computed coefficients and currently estimated coefficients ( C ). The Direct Learning approach uses a parameter, μ, which is the convergence factor that defines the step size for learning coefficients.
  • Page 10 Preliminary Technical Data In this DPD implementation, the GMP is used to model the PA in the baseband. A GMP model is represented as where x(n) is a complex baseband input signal to the DPD actuator, y(n) is a complex valued output signal of the DPD actuator, and c is the complex valued coefficient of the GMP terms.

  • Page 11: Initializing Pre-Calibrated Coefficients During Start-Up

    Preliminary Technical Data The equations below represent the GMP terms that are mapped to LUT10, LUT11 and LUT12 described in Figure 13. Figure 13. Example of User Programmed GMP Model = |x(n-2)| .x(n-1) + |x(n-2)| .x(n-1) lut10 = |x(n-3)|.x(n-1) + |x(n-3)| .x(n-1) + |x(n-3)| .x(n-1) lut11...
  • Page 12 Preliminary Technical Data In the single frequency band use case, all four transmit channels are working in the same frequency band as shown in Figure 14. Single Frequency Band Use Case Note the PA model will be the same for all four channels. Figure 14.

  • Page 13: Dpd Sample Capture

    Preliminary Technical Data Figure 15. Case 2 Dual Band Use Case Configuration The API sequence for programming DPD models in a dual frequency band use case are shown below. The factory calibrated coefficients can be programmed into the transceiver through the API adi_adrv9025_DpdModelConfigSet() for the two pairs of transmit channels as described in the previous section.
  • Page 14 Preliminary Technical Data accuracy of coefficient estimation. ADI recommends the number of samples be set to 16384, which provides a good balance between accuracy of estimation of coefficients and processing time. For successful captures, the transmitter to observation channel external signal routing needs to be conveyed to the firmware through the API adi_adrv9025_TxToOrxMappingSet().
  • Page 15 Preliminary Technical Data penalizing the rest of the system operation. In order to do so, the system designer must study the worst case signal statistics. This DPD contains only one adaptation engine, so the capture mechanism is shared between all active channels. Figure 18.

  • Page 16: Dpd Dynamics

    Preliminary Technical Data There are additional considerations that a system developer needs to take into account for configuring the DPD in TDD mode. In DPD Sample Capture in TDD Mode TDD mode, the DPD sample capture process spans multiple TDD downlink slot periods (Tx ON periods), with each batch of 4096 samples captured during one TDD downlink slot period (Tx ON period) through the peak detection process highlighted in the previous section.
  • Page 17 Preliminary Technical Data Table 3. The update criteria is described in the following section. DPD MODE1 -The model defined by M-Table is updated when the rms power of DPD capture samples exceeds previously recorded maximum rms power as described in ADI_ADRV9025_DPD_MODE1 section in Table 3. DPD MODE2 –The model defined by M-Table is updated only when the rms power of DPD capture samples exceeds M-Threshold specified by the configuration adi_adrv9025_DpdTrackingConfig_t.dpdMThreshold and the rms...
  • Page 18 Preliminary Technical Data DPD Mode of Description Operation Figure 20. DPD Mode 0 Update Example ADI_ADRV9025_DPD_M DPD coefficients corresponding to the GMP model are updated only if the RMS power measured ODE1 by the DPD exceeds the previously recorded maximum RMS power by the DPD algorithm. The RMS power is calculated on the samples captured by the DPD for coefficient computation.
  • Page 19 Preliminary Technical Data DPD Mode of Description Operation up table is active until the next DPD update. The RMS power threshold separating the low power and high power region is user configurable through the parameter adi_adrv9025_DpdTrackingConfig_t. dpdMThreshold. The RMS power is calculated on the samples captured by the DPD for coefficient computation.
  • Page 20 Preliminary Technical Data Figure 23. DPD Dynamics and Tx Low Power Threshold The M-Threshold is a max power threshold specified by adi_adrv9025_DpdTrackingConfig_t.dpdMThreshold that is valid only in Transmitter M-Threshold DPD mode 2 operation (adi_adrv9025_DpdTrackingConfig_t.dpdUpdateMode = ADI_ADRV9025_DPD_MODE2). There are two DPD models (M-Table, C-Table) that the DPD tracking calibration maintains and updates. The DPD model update mechanism in DPD mode 2 operation is described in Table 4.

  • Page 21: Dpd Regularization

    Preliminary Technical Data Figure 24. ADRV9025 DPD Dynamics in DPD Mode 2 The observation receiver low power threshold can be used to compare observation samples against the threshold specified by Observation receiver Low Power Threshold adi_adrv9025_DpdTrackingConfig_t.minAvgSignalLevelOrx in linear scale, to determine if a DPD update needs to be applied. This can help avoid DPD updates when the signal level is low and, consequently, the signal to noise ratio of the observed samples is poor.
  • Page 22 Preliminary Technical Data For the AM-AM characteristics shown above, the effect of low regularization and optimum regularization on DPD is shown in Figure 26. DPD Regularization for Decreasing Sensitivity to Sparse Data Figure 27. With low regularization, the DPD algorithm has a tendency to overfit resulting in high power scattering. With the optimum regularization, the sensitivity of DPD algorithm to sparse data in high power is minimized.

  • Page 23: Dpd Robustness

    Preliminary Technical Data DPD ROBUSTNESS This section provides an overview of the features that enhance DPD robustness. These features include DPD stability metrics and flexible architecture for setting up recovery actions based on these pre-defined DPD metrics. The user can optionally turn on the DPD robustness feature to protect DPD against erroneous adaptations in abnormal conditions.
  • Page 24 Preliminary Technical Data One of the seven DPD stability metrics described in the dpdMetric adi_adrv9025_DpdMetric_e previous section The user can select a greater than or less than comparator for defining a fault condition. Eg: The user comparator adi_adrv9025_DpdComparator_e can define a fault condition where Tx RMS power is greater than a certain threshold and ORx RMS power is lesser than a certain threshold.
  • Page 25 Preliminary Technical Data Select Error Greater Than The DPD recovery actions configured in the firmware on startup are listed in Table 9. Table 9. Default Recovery Action Matrix Recover Action if Recover Action if Recover Action if Recover Action if Metric Low Threshold is Low Threshold...

  • Page 26: Dpd Actuator Gain Monitoring For Robustness

    Preliminary Technical Data RECOVERY Do Nothing Skip DPD LUT Updates Do Nothing Skip DPD LUT Updates ACTION AND Reset DPD coefficients to unity gain(Actuator output = Actuator input) FAULT Indirect EVM OR Mean Tu Indirect EVM Only CONDITION Power OR Peak Tu Power The following is an example code snippet to setup recovery actions shown in the matrix above: Figure 28.
  • Page 27 Preliminary Technical Data Figure 29. DPD Actuator Gain Monitoring Functional Diagram The following adjustments listed in Table 10 can be used to configure the DPD actuator gain monitoring feature. DPD Actuator Gain Monitoring Configurations Table 10. DPD Gain Monitoring Configurations Gain Monitor Configuration Description adi_adrv9025_DpdActGainMonitorCtrl_t.
  • Page 28 Preliminary Technical Data dpdGainMonitorIIRDecay Decay rate can be calculated as follows; N = (65536/(averaging_window_size/2)) where the decay rate will be equal to log (N). The API functions used to control gain monitoring are listed in Table 11. DPD Actuator Gain Monitoring API Table 11.
  • Page 29 Preliminary Technical Data Figure 30. Example Python Script to Configure Gain Monitoring Feature Rev. PrA | Page 29 of 82...
  • Page 30 Preliminary Technical Data The flow chart in Figure 31 describes the function of the gain monitoring state machine. The DPD gain monitoring, once enabled, DPD Actuator Gain Monitoring + Model Switching State Machine Representation runs independently from the DPD actuator. It monitors the gain of the signal across the actuator until it is turned off, as shown in the state diagram.

  • Page 31: Dpd Actuator Bypass

    DPD ACTUATOR BYPASS The ADRV9029 DPD provides a mechanism to bypass pre-distortion through GPIO control. The GPIO input is level sensitive and activates the unity gain model for the duration of time where the GPIO level is high. The GPIO based DPD actuator bypass is typically used for antenna calibrations in M-MIMO applications, where the pre-distortion must be disabled for the duration of antenna calibration to prevent pre-distortion from affecting antenna calibration accuracy.

  • Page 32: Dpd Status

    Preliminary Technical Data NOTE: Please ensure that the GPIO assigned for controlling DPD actuator bypass is driven to a low state during initialization to Figure 34. Post MCS Init Stream GPIO Configuration Structure prevent interference with initial calibrations. DPD STATUS The user can obtain the status of the DPD tracking calibration during runtime through the API command adi_adrv9025_DpdStatusGet() which updates a data structure of type adi_adrv9025_DpdStatus_t supplied by the user.

  • Page 33: Recommended Sequence For Enabling The Dpd Tracking Calibration

    Preliminary Technical Data RECOMMENDED SEQUENCE FOR ENABLING THE DPD TRACKING CALIBRATION The sequence for running DPD tracking calibrations is shown in Table 14. Table 14. DPD Tracking Calibration Bringup Sequence Step Action APIs used Program the device and run initial calibrations(including TxQEC initial calibration) with (Utility function adi_daughterboard_Program() can be used the PA turned off.

  • Page 34: Dpd Stability Metrics Characterization

    Preliminary Technical Data Step Action APIs used Monitor CLGC tracking calibration status adi_adrv9025_ClgcStatusGet DPD STABILITY METRICS CHARACTERIZATION The following stability metrics are at the disposal of the user for defining stability: Transmit power thresholds Observed power thresholds • Direct EVM - Difference between measured pre DPD transmitted and observed samples •...
  • Page 35 Preliminary Technical Data Figure 37. Direct EVM for the Best ACLR Performance Shown below is the trend for the EVM and error stability metrics for different observation receiver channel attenuation values. It Observation Receiver Attenuation vs Stability Metrics can be observed that as observation receiver attenuation is increased, the error percentage also increases. The same might be true for a low SNR transmitter to observation receiver channel.
  • Page 36 Preliminary Technical Data Figure 39. ORx Interference vs Stability Metrics Shown in Figure 40 is the degradation of stability metrics with decreasing transmitter signal power. When the signal level is close Transmit Signal vs Stability Metrics to –36 dBFS, it can be observed that the EVM percentages are close to 5%. At a transmitter signal level close to –46 dBFS, the EVM percentages are close to 15%, causing further ACLR degradation.

  • Page 37: Dpd Characterization For Optimizing M-Threshold

    Preliminary Technical Data Interference/high noise levels in Tx-ORx channels can cause the EVM and error percentages to increase. Fault conditions and corresponding recovery actions can be defined for EVM numbers to avoid bad DPD updates. • As Tx signal level decreases, the EVM percentages increase. However, an argument can be made that DPD might not be required at lower signal levels for certain PAs.

  • Page 38: Typical Procedure To Set Up Dpd Using Gui

    TYPICAL PROCEDURE TO SET UP DPD USING GUI The DPD tab on the ADRV9029 TES GUI is the primary evaluation tool for the DPD feature. In addition, the DPD application programming interface (API) and dynamic link library (DLL) may be used to interact and control the DPD via Python or C#. The ADRV9029 GUI supports an IronPython tab that can be used for scripting purposes.
  • Page 39 Preliminary Technical Data After loading the waveform, set the ‘Tx attenuation’ to get the desired output power. The waveform is transmitted using the ‘Play’ button on the transmit tab. After playing the waveform, the user can read the power at the output of the PA via a spectrum analyzer or a power meter (more accurate method).
  • Page 40 Preliminary Technical Data Select desired Tx channel to apply settings. Figure 47. Configure DPD Tracking Config Apply DPD tracking configuration by clicking on ‘Apply Tracking Config’, as shown in Figure 48. Run Path Delay initial calibration using ‘Run Path Delay Init Cal’ button. Apply DPD model on the M or C tables using ‘Apply Model on Device from M Table’...
  • Page 41 Preliminary Technical Data The steps below outline the procedure to change the DPD model or apply a different tracking configuration parameter. Figure 49. Get DPD Status and Statistics Disable DPD tracking by unchecking the Tx channel under consideration in Figure 48 and click ‘Enable DPD on selected channels (only)’.

  • Page 42: Crest Factor Reduction (Cfr)

    CREST FACTOR REDUCTION (CFR) The ADRV9029 variant provides crest factor reduction to assist in keeping power amplifiers linear. This functionality is only available in the ADRV9029 variant. A typical communications RF sub-system consists of an antenna, Power Amplifier (PA), and RF transceiver that translates digital baseband signals to RF, as shown in Figure 50.

  • Page 43: Cfr Algorithm Overview

    The ADRV9029 implements CFR using a variation of the pulse cancellation technique by subtracting a pre-computed pulse from the detected peaks to bring the signal within the PA’s linear range. The CFR block consists of three copies of CFR engines, each of which uses a detection threshold to detect the peaks and a correction threshold to which the detected peaks are attenuated.

  • Page 44: Overview Of Blocks Used In Cfr

    Preliminary Technical Data Figure 53. CFR Engine Architecture in ADRV9029 The complex IQ signal (transmitter data) goes into a variable delay FIFO and correction is applied at its output. The input data also goes into an interpolator, which can interpolate by 1×, 2×, or 4× times the input sample rate. This interpolated data is then fed into a peak detector.

  • Page 45: Api Software Integration

    Preliminary Technical Data The interpolator can be programmed to interpolate the data by 4, 2, or 1. The main purpose of the interpolator is to produce finer Interpolator timing resolution so that the peak detector can find the location of the peaks more accurately. The interpolator takes in the transmitter data and outputs the interpolated data to the peak detector.
  • Page 46 Preliminary Technical Data The ADRV9029 also provides the flexibility to change correction pulses on the fly without needing to run CFR initialization Procedure for Updating Correction Pulses On-the-Fly calibration. The recommended procedure assumes user already successfully followed the initial procedure for setting up CFR given in Procedure for setting up CFR section.
  • Page 47 Preliminary Technical Data Table 16. Adi_adrv9025_CfrCtrlConfig_t Data Structure Valid Data Type Structure Member Description Values Mask consisting of 'OR'ed transmitter channels for which uint32_t txChannelMask 0..15 the CFR core config will be applied (1 bit for each channel). adi_adrv9010_CfrMod Selects the mode in which CFR is required to operate in. cfrMode eSel_e Currently, Mode 1 is the only supported mode.
  • Page 48 Preliminary Technical Data This function can be used to program the complex coefficients of the final CFR correction pulse. This function is intended to be used when the CFR engine is operating in ADI_ADRV9025_CFR_MODE1 mode. This function expects the user to provide only the first half the correction pulse since it is assumed that the correction pulse is conjugate symmetric.
  • Page 49 Preliminary Technical Data This function may be called only when the target transmitter channel is off after device initialization and the ARM processor boot up is complete. Table 20. adi_adrv9025_ CfrCorrectionPulseRead_v2(…) Parameters Parameter Description *device Pointer to the device settings structure txChannel Target transmitter channel whose correction pulse coefficients are requested maxCorrectionPulsesToRead...
  • Page 50 Preliminary Technical Data Table 22. adi_adrv9025_ CfrEnableGet(…) Parameters Parameter Description *device Pointer to the device settings structure txChannel Target transmitter channel whose enable status is requested *cfrEnable Pointer to a CFR enable structure which will be updated with the enable settings in the device adi_adrv9025_CfrHardClipperConfigSet(…) int32_t adi_adrv9025_CfrHardClipperConfigSet(adi_adrv9025_Device_t *device, adi_adrv9025_CfrHardClipperConfig_t cfrHardClipperConfig[], uint8_t...
  • Page 51 Preliminary Technical Data Table 25. CFR Hard Clipper Settings Structure Member Description Data Type Structure Member Valid Values Description Mask consisting of 'OR'ed transmitter channels for which the hard clipper config will be applied (1 bit for each uint32_t txChannelMask 0..15 channel) 1- Enable hard clipper on the channels requested, 0 -...
  • Page 52 Preliminary Technical Data Table 28. CFR Error Structure Member Description Structure Member Description Error code to convey that the mandatory CFR configs were not done. Not ADI_ADRV9025_CFR_CONFIGURATION_ERROR active/used Error code to convey that an unsupported ADI_ADRV9025_CFR_PROG_PULSE_MODE_ERROR pulse mode was selected. Error code to convey that the transmitter ADI_ADRV9025_CFR_INPUT_RATE_HIGH_ERROR channel sample rate is higher than 245.76...

  • Page 53: Typical Procedure To Set Up Cfr Using The Gui

    Preliminary Technical Data Table 30. adi_adrv9025_ CfrActiveCorrectionPulseSet(…) Parameters Parameter Description *device Pointer to the device settings structure txChannel A mask consisting of ORed transmitter channels for which the requested correction pulse is required to be activated cfrCorrectionPulseSel Selection for the correction pulse to activate The adi_adrv9025_ CfrStatistics_t data structure holds the transmitter CFR engine statistics for each transmitter Channel.
  • Page 54 Preliminary Technical Data Figure 55. Load Waveform Using Transceiver Evaluation Software After loading the waveform, it is transmitted using the ‘Play’ button on the transmit tab. As an example, an LTE 20 MHz waveform with PAR of 12.2dB is used here. The uncorrected waveform’s Complementary Cumulative Distribution Function (CCDF) is shown in Figure 56.
  • Page 55 Preliminary Technical Data The DFE tab is used in TES to set up the CFR engines as shown in Figure 57. Figure 57. CFR Engine Setup Using TES ‘Load File’ can be used to load the correction pulse. This correction pulse is specific to the waveform being used (LTE 20 MHz in example shown) and is sampled at the peak detection rate.
  • Page 56 Preliminary Technical Data Figure 58. Enabling CFR Using TES After clicking on ‘Apply’ (which runs the CFR init cal), the CFR engines will be enabled, and the corrected waveform can be observed on the spectrum analyzer as shown in Figure 59. As we can see in , the corrected CCDF curve has a PAR of 8.75 dB which corresponds to the CFR peak threshold that we Figure 59.
  • Page 57 Preliminary Technical Data In this section, we will study the impact of using the CFR engines within the transceiver on EVM performance. The same LTE 20 Impact on EVM MHz tone (PAR=12.67 dB) as used in the section above is used here as an example. The set up information for this waveform is described below.
  • Page 58 Preliminary Technical Data Applying the CFR settings discussed in earlier section, where we have the target PAR set to 8 dB, the degradation observed in EVM is shown in Figure 61. Figure 61. Observed EVM After Applying CFR (Target PAR = 8 dB) We can see above that the rms EVM degraded from 0.6 % to 2% due to application of CFR.
  • Page 59 Preliminary Technical Data Figure 62. Target PAR vs EVM Rev. PrA | Page 59 of 82...

  • Page 60: Closed Loop Gain Control (Clgc)

    Preliminary Technical Data CLOSED LOOP GAIN CONTROL (CLGC) CLGC OVERVIEW Closed Loop Gain Control (CLGC) is a closed-loop tracking calibration which adjusts front end Tx attenuations to maintain a constant desired gain in the Tx path from baseband input to PA output such that the PA output power is constant with respect to changes in temperature or other variations.

  • Page 61: Clgc Algorithm Overview

    Preliminary Technical Data CLGC ALGORITHM OVERVIEW The CLGC algorithm is designed to maintain a constant loop gain, and overcome any minor fluctuations in the PA output power due to variations in temperature and other operating conditions. Loop gain is defined as the ratio of the power level of observed data to the power level of the baseband transmit data ������������...

  • Page 62: Enable The Clgc Tracking Calibration

    Preliminary Technical Data is the equivalent additive noise from the entire loop, which may include thermal noise, quantization noise, phase noise and nonlinear distortions. • is the desired loop gain set by the user based on a nominal level of and an expected output power of the PA.

  • Page 63: Clgc Modes Of Operation

    Preliminary Technical Data Parameter Data Type Description Value The 64 bit ‘OR’ed mask that consists of (ADI_ADRV9025_TRACK_TX1_CLGC | enableMask uint64_t tracking calibrations to enable/ disable ADI_ADRV9025_TRACK_TX2_CLGC | ADI_ADRV9025_TRACK_TX3_CLGC | ADI_ADRV9025_TRACK_TX4_CLGC) enableDisableFlag Enumeration Indicates whether the mask value passed ADI_ADRV9025_TRACKING_CAL_ENABLE in enableMask parameter is to be used for enabling or disabling the tracking Similarly, to disable the CLGC tracking calibration, the user can set the argument enableDisableFlag to an enumeration valud calibration...
  • Page 64 Preliminary Technical Data Figure 65. CLGC modes of operation during bring up Rev. PrA | Page 64 of 82...

  • Page 65: Clgc Measurement

    Preliminary Technical Data CLGC MEASUREMENT The CLGC measurement cycle is common to both passive loop gain measurement and active loop gain control modes. In active loop gain control mode, the Tx attenuation is also adjusted by the CLGC algorithm. The Tx attenuation adjustment is covered in the next section.
  • Page 66 Preliminary Technical Data The complete CLGC measurement cycle for a single update period is captured in Figure 5. The flowchart explains the Figure 66. Tx and ORx qualifying threshold for CLGC measurement measurement and it’s interactions with the measurement parameters described in Table 4. The important thing to note is that the CLGC only captures samples until the Tx/ORx threshold and the ORx SNR criteria is met.

  • Page 67: Clgc Tx Attenuation Control

    Preliminary Technical Data Figure 67 CLGC Measurement Cycle CLGC TX ATTENUATION CONTROL As shown in Error! Reference source not found., the CLGC algorithm tunes the Tx front end attenuation in the transceiver in order to converge to the requested loop gain. The user is required to configure the Attenuation limits and the step size parameters through the API adi_adrv9025_ClgcConfigSet().
  • Page 68 Preliminary Technical Data when ORx data is corrupted, and loop gain estimated is bad. Setting the minimum Tx attenuation limit ensures that the PA is not over driven. Maximum Tx Attenuation The absolute value of the upper limit of Tx adi_adrv9025_ClgcConfig_t.
  • Page 69 Preliminary Technical Data Figure 69. CLGC Active Loop Gain Control update cycle Rev. PrA | Page 69 of 82...

  • Page 70: Clgc Api Summary

    Preliminary Technical Data CLGC API SUMMARY Table 39. CLGC API Software Overview API Function Description adi_adrv9025_ClgcConfigSet Configures the CLGC measurement and Tx attenuation control parameters as described in the previous sections. This API can also be used to turn on/off loop gain control adi_adrv9025_ClgcConfigGet Retrieves the CLGC configuration currently active in the ADRV9025 device...

  • Page 71: Clgc Errors

    Preliminary Technical Data Table 41. Summary of CLGC status info Parameter Description Represents the Tx - ORx loop gain equal to (ORx RMS Power)/(Tx RMS Power) in linear scale clgcLoopGain measured during the last CLGC update clgcTxRmsPower Tx RMS power in linear scale measured during the last CLGC update clgcOrxRmsPower Orx RMS power in linear scale measured during the last CLGC update activeTxAttenIndex...

  • Page 72: Clgc Capture Errors

    Preliminary Technical Data The minimum Tx attenuation can be configured via such that the loop gain falls within the adi_adrv9025_ClgcConfigSet( ) API. range acceptable to the user. ADI_ADRV9025_CLGC_HI_LIMIT The absolute value of the upper limit of Tx Adjust the Tx attenuation upper •...
  • Page 73 Preliminary Technical Data ADI_ADRV9025_CLGC_CAP_SAVE_FUNC_ERR CLGC capture did not complete Disable CLGC. Verify that other cals • successfully. This error occurs if are still running. the correlator hardware in the If other cals are still running, then it • device was not successfully might require a full firmware reset.

  • Page 74: Sequence For Enabling Clgc Tracking Calibration

    Preliminary Technical Data SEQUENCE FOR ENABLING CLGC TRACKING CALIBRATION Table 44. DPD Tracking Cal Bringup Sequence Step Action ADRV9025 APIs used Program the device and run initial calibrations(including TxQEC initial calibration) with the PA turned off. (Utility function adi_daughterboard_Program() can be used to program the device) Setup external Tx to ORx mapping adi_adrv9025_TxToOrxMappingSet...

  • Page 75: Case Study For Configuring Clgc Batch Sampling Period

    Preliminary Technical Data CASE STUDY FOR CONFIGURING CLGC BATCH SAMPLING PERIOD Shown below is the demodulated version of the 5G NR TM2 signal under test. The signal has a bandwidth of 100Mhz, and a sub- Signal Under Test carrier spacing of 30Khz,(numerology u=1). The signal has an RMS power of ~-38.14dBFS. Figure 70.
  • Page 76 Preliminary Technical Data Figure 71. Time-Frequency Resource Block Allocations of 5GNR TM2 signal under test The signal has most of the synchronization data and reference symbols concentrated in 2 subcarriers at the edges of the Frequency Spectrum of the Signal spectrum, and one sub-carrier in the middle of the 100Mhz bandwidth.
  • Page 77 Preliminary Technical Data Figure 73. Time Domain view of the 5GNR TM2 signal under test Shown below is the gain vs Pout over frequency of SKY66397-12 PA for a single carrier CW tone at 2.49GHz, 2.59GHz, 2.63GHz, PA Characteristics and 2.69GHz respectively in band n41 operation(2.5-2.7GHz). It can be observed that the carrier at 2.69GHz experiences a gain of less than 1dB compared to the carrier at 2.49GHz at lower powers, and a gain of less than 2dB at higher power levels.
  • Page 78 Preliminary Technical Data Figure 75. Forward gain of SKY66397 PA vs frequency Shown in Figure 76 is a simplified overview of CLGC loop gain estimation. A more detailed flow of measurement can be found in CLGC Loop Gain Estimation CLGC Measurement section. The CLGC algorithm captures Tx and ORx data in batches. If the captured data meets the required threshold and SNR criteria, the CLGC algorithm proceeds to estimate the loop gain and apply the Tx attenuation correction.
  • Page 79 Preliminary Technical Data Based on experiment results, a direct correlation between Tx output power variation, and CLGC loop gain variation was noticed. Analysis of Results With 10us Batch Sampling Period Shown below is the CLGC loop gain variation data collected with the 5GNR TM2 signal(described in Section 2) as the test vector, with target loop gain set to 1.5dB.

  • Page 80: Clgc Recommendations

    Preliminary Technical Data Figure 79 captures CLGC loop gain monitored over 1 hour with the TM2 signal described in Signal Under Test section with CLGC Results With Increased CLGC Samspling Period sampling period increased to 1.5ms from 10us. The loop gain by and large remains stable within +/-0.05dB variation, with only 3 iterations where the loop gain varies by greater than 0.05dB.
  • Page 81 Preliminary Technical Data Compare the statistics from a TM2 signal from 1 with a fully filled TM3.1 NR100 signal in Figure 78 which has an rms value of - 12dBFS per frame. A 10us moving average of the TM3.1 NR100 signal results in a mean of -11.99dBFS, and a standard deviation of 0.12dB, which is close to the frame rms of -12dBFS.
  • Page 82 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

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