SWRA577A October   2017  – November 2020 AWR1243 , AWR1443 , AWR1642 , AWR1843 , AWR1843AOP , AWR2243 , AWR6843 , IWR1443 , IWR1642 , IWR1843 , IWR6443 , IWR6843 , IWR6843AOP , LP87524B-Q1 , LP87524J-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Power Supply Ripple and Noise Specifications
  4. 3Reference Solution
  5. 4Low Cost LC Filter Solution
    1. 4.1 LDO vs LC Filter Scheme Comparison
      1. 4.1.1 Waveguide Loopback Tests
      2. 4.1.2 Spur/Noise Floor Level
      3. 4.1.3 Voltage Transient Behavior
    2. 4.2 System Tests
      1. 4.2.1 Sensor Configuration
      2. 4.2.2 System Test With Static Object
      3. 4.2.3 Spur/Noise Floor Level
  6. 5Summary

Spur/Noise Floor Level

For Spur level measurements, a continuous tone at 77 GHz is transmitted and the received signal is analyzed with 524288 samples for the presence of the PMIC switching frequency spur at ~4 MHz. The Rx gain is set at 48dB with an observation that PMIC spur level tracks the Rx gain.

GUID-BDCF26D7-A73F-4F45-B55C-8CDC72CE36D6-low.gifFigure 4-6 LDO Scheme –Spur Level
Note:

No PMIC switching Frequency (approximately 4 MHz) Spur seen.

GUID-C6DEB268-ADC5-43C1-ADE1-6738212E737F-low.gifFigure 4-7 LDO Scheme - Noise Floor With Tx –OFF
GUID-521D0CC1-01E2-411B-8DCE-D51FC5E61DA5-low.gifFigure 4-8 LC Filter Scheme – Spur Level
Note:

PMIC spur is observed at -84.53 dBFS at RX gain of 48dB.

GUID-C6DEB268-ADC5-43C1-ADE1-6738212E737F-low.gifFigure 4-9 LC Filter Scheme - Noise Floor With Tx –OFF