SPRACP3C November   2019  – December 2021 AWR6843 , AWR6843AOP , IWR1443 , IWR1642 , IWR6443 , IWR6843 , IWR6843AOP

 

  1.   Trademarks
  2. 1Introduction
  3. 2Typical Certification Procedure
  4. 3Regulatory Compliance Overview
    1. 3.1 European Union Regulations - Radio Equipment directive (RED)
      1. 3.1.1 Efficient Use of the Radio Spectrum (EN 305 550)
      2. 3.1.2 RF Exposure Limit - EN 62311
      3. 3.1.3 Electrical Safety - EN 62368
      4. 3.1.4 ElectroMagnetic Compatibility (EMC) - EN 301 489-1
    2. 3.2 Federal Communications Commission (FCC)
      1. 3.2.1 End Equipment and FCC Clause
      2. 3.2.2 Fundamental Emmision levels
      3. 3.2.3 Spurious Emission
      4. 3.2.4 Frequency Stability
      5. 3.2.5 Radiation Exposure Requirement
      6. 3.2.6 FCC Waiver and Other Relevant Information
    3. 3.3 Applicable Terms and Equations
      1. 3.3.1 Duty Cycle Factor
      2. 3.3.2 Effective Isotropic Radiated Power (EIRP)
      3. 3.3.3 Friis Equation
      4. 3.3.4 Far-Field Boundary
  5. 4Tools and Setup
    1. 4.1 Hardware Setup
    2. 4.2 MMWAVESTUDIO
      1. 4.2.1 Running LUA Scripts
    3. 4.3 mmWave Visualizer
    4. 4.4 IWR6843ISK-ODS Test Case
  6. 5Common Issues and Resolutions
    1. 5.1 Peak Power
    2. 5.2 Occupied Bandwidth
    3. 5.3 Spurious Emissions
      1. 5.3.1 14.4-Ghz Harmonics
      2. 5.3.2 Suggested Resolution
        1. 5.3.2.1 Hardware Measures
        2. 5.3.2.2 Software Measures
    4. 5.4 Overshoot
    5. 5.5 Frequency Stability
      1. 5.5.1 Generating CW Signal
      2. 5.5.2 Frequency Stability Over Temperature and Voltage Range
  7. 6References
  8. 7Revision History

5.5.2 Frequency Stability Over Temperature and Voltage Range

Problem Statement: Frequency is not within the limit over the temperature and voltage range.

Solution: Adjust the capacitors on the clock to ensure ~0 PPM deviation at room temperature.

Deep Dive:

FCC part 15.255, Frequency stability: Fundamental emissions must be contained within the frequency bands specified in this section during all conditions of operation. Equipment is presumed to operate over the temperature range −20 to + 50 degrees Celsius with an input voltage variation of 85% to 115% of rated input voltage, unless justification is presented to demonstrate otherwise.

GUID-7BAFC6D2-7326-44FF-8210-5BC7F466C331-low.pngFigure 5-6 40-Mhz Crystal Capacitance

Equation 17. LoadCapacitor CL=Cf1 ×  Cf2Cf1+Cf2+Cp
where
  • Cp is the parasitic capacitance
  • Cf1 and Cf2 are capacitors in parallel

IWR6843 requires a 40-MHz crystal or external oscillator to the CLKP pin; this is used for initial boot up and as reference for the internal APLL and other clocks. For the IWR6843ISK EVM, the crystal is implemented as shown in Figure 5-6. The capacitors are chosen to satisfy requirement shown in Table 5-2.

Table 5-2 Capacitor Requirements
NameDescriptionMinTypMaxUnit
FpParallel resonance crystal frequency40MHz
CLCrystal load capacitance5812pF
Temperature rangeExpected temp range of operation-40105°C
Frequency toleranceCrystal frequency tolerance-5050ppm

To meet the FCC requirements, the capacitors should be tuned such that the oscillator frequency deviation is at 0 ppm at room temperature and frequency deviation stays within the frequency band across voltage and temperature .