SPRACV2 November   2020 AWR1843 , AWR2243

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Background – Simple Single-Chip Applications
  3. 2Cascade Incoherence Sources and Mitigation Strategies
    1. 2.1 PCB Routing Imbalances and Device Processes
    2. 2.2 Temperature Drifts
    3. 2.3 Scheduling of Run Time Calibrations
  4. 3Enabling Cascade Coherence and Improved Phase Performance
    1. 3.1 High-Level Summary
      1. 3.1.1 Sequence of Proposed Steps and Introductory Flow Diagrams
    2. 3.2 Saving RF INIT Calibration Results at Customer Factory
      1. 3.2.1 Note on LODIST Calibration
      2. 3.2.2 TX Phase Shifter Calibration and Saving Results at Customer Factory
    3. 3.3 Corner Reflector-Based Offsets Measurement at Customer Factory
      1. 3.3.1 Corner Reflector-Based Inter-Channel Imbalances
      2. 3.3.2 Corner Reflector-Based TX Phase Shifter Errors
    4. 3.4 Restoring Customer Calibration Results In-Field
      1. 3.4.1 Restore RF INIT Calibrations Results In-Field
      2. 3.4.2 Restore TX Phase Shift Calibration Results In-Field
    5. 3.5 Host-Based Temperature Calibrations In-Field
      1. 3.5.1 Disabling AWR Devices’ Autonomous Run Time Calibrations
      2. 3.5.2 Enabling Host-Based Temperature Calibrations of Inter-Channel Imbalances
      3. 3.5.3 Switching of DSP Imbalance Data
      4. 3.5.4 Enabling TX Phase Shifter’s Host-Based Temperature Calibrations
        1. 3.5.4.1 Estimating TX Phase Shift Values at Any Temperature
        2. 3.5.4.2 Temperature Correction LUTs for AWR1843TX Phase Shifter
        3. 3.5.4.3 Temperature Correction LUTs for AWR2243 TX Phase Shifter
        4. 3.5.4.4 Restoring TX Phase Shift Values – Format Conversion
        5. 3.5.4.5 Restoring TX Phase Shift Values – Transition Timing and Constraints
        6. 3.5.4.6 Typical Post-Calibration TX Phase Shifter Accuracies
        7. 3.5.4.7 Correcting for Temperature Drift While Sweeping Across Phase Settings
        8. 3.5.4.8 Amplitude Stability Across Phase Shifter Settings
        9. 3.5.4.9 Impact of Customer PCB’s 20-GHz Sync Path Attenuation on TX Phase Shifters
      5. 3.5.5 Ambient and Device Temperatures
  5. 4Concept Illustrations
  6. 5Miscellaneous (Interference, Gain Variation, Sampling Jitter)
    1. 5.1 Handling Interference In-Field
    2. 5.2 Information on TX Power and RX Gain Drift with Temperature
    3. 5.3 Jitter Between Chirp Start and ADC Sampling Start
  7. 6Conclusion
  8.   A Appendix
    1.     A.1 Terminology
    2.     A.2 References
    3.     A.3 Flow Diagrams for Proposed Cascade Coherence Scheme
    4.     A.4 LUTs for TX Phase Shifter Temperature Drift Mitigation
    5.     A.5 Circular Shift of TX Phase Shifter Calibration Data Save and Restore APIs

A.1 Terminology

Table 7-1 briefly explains some terms used in this note.

Table 7-1 Terminology
Device TI’s radar system on chip, such as AWR1243or AWR2243
Single chip A usage scenario where a radar sensor includes only one AWR device and performs coherent processing of data only within frames and not across frames.
Cascade A radar system operating multiple AWR devices together to improve sensing
Advanced single chip A usage scenario where a single chip radar sensor performs coherent processing across multiple frames, thereby needing phase stability across frames.
Host The processor or microcontroller that controls the cascade’s multiple AWR devices
DSP The (internal or external) processor which processes the AWR devices’ RX ADC data
Analog Mm-wave, RF, analog circuits and subsystems in the device
Analog configurations Bias currents, voltages, capacitor, resistor values that control the analog operation
Offsets A collective term for errors, such as inter-channel imbalances, TX phase shifter nonlinearity errors.
Customer The customer of the AWR devices who manufactures the radar sensor PCB using them.
Non-volatile memory (NVM) A memory element in the sensor which can be populated during the factory calibration process (e.g. with calibration results) and which can be read in field.
Factory calibration temperature Temperature at which Customer factory is performed (typically 25C).
Cold, Mid, Hot settings A nomenclature to illustrate the AWR analog settings corresponding to broad temperature ranges.
DoE, DoE devices Design of Experiments, and associated devices. This refers to intentional skewing of device manufacturing process parameters to manufacture a few devices for TI lab evaluation, in order to capture/understand the effect process variation in mass manufacture of devices.
INL error Integrated Non Linearity error, referring to TX phase shifter’s deviation from ideal 0 to 360o characteristics.