SNVU695A June   2020  – January 2022 LP87702-Q1


  1. 1Introduction
  2. 2xWR Power Supply Requirements
    1. 2.1 Recommended Supply Voltage Requirements
    2. 2.2 Input Supply Current Requirements
    3. 2.3 Input Supply Ripple Requirements
  3. 3Power Solution
    1. 3.1 1.0 V and 1.8 V RF Rail LC Filters
  4. 4Measurements
  5. 5Schematic
  6. 6Bill of Materials
  7. 7Conclusion
  8. 8References
  9. 9Revision History

Input Supply Ripple Requirements

1.0 V RF and 1.8 V RF rails have very tight ripple specifications as ripple noise on these two rails affect the RF performance. Ripple on 3.3 V and 1.2 V rails do not directly affect the RF performance, but system level noise coupling could affect the RF performance; hence, it is necessary to minimize the ripple on these rails as well. Switching regulators have a fundamental ripple noise at switching frequency and this needs to be reduced. Table 2-4 provides the AWR device ripple noise specification. This ripple specification assumes a -105 dBc target spur level. If a higher spur can be tolerated based on the system requirements, then the ripple specifications can be relaxed. There is a dB-to-dB correlation between supply ripple and spur level. For example, a 1 dB increase in supply ripple will result in 1 dB increase in spur level.

Table 2-4 AWR1843 Ripple Specification
Frequency (kHz)RF RailVCO/IF Rail
1.0 V (Internal LDO bypass) (µVRMS)1.3 V (µVRMS)1.8 V (µVRMS)