SBAA591 December   2023 REF54

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Flicker Noise Measurement Method
  6. 30.1 Hz to 10 Hz Band Pass Filter Design for Reference Noise Measurement
    1. 3.1 Filter Schematic
    2. 3.2 TINA - TI simulations
    3. 3.3 Component Selection
  7. 4Measurement Setup
    1. 4.1 REF54250CDR Noise Measurement Setup
  8. 5Filter Board Design
    1. 5.1 Schematic
      1. 5.1.1 Schematics Images
    2. 5.2 Layout
    3. 5.3 Bill of Materials
  9. 6References

1 Introduction

Noise of the reference couples with the data converter’s quantization error and impacts the resolution of the overall signal chain. Designers must keep the reference noise sufficiently small so that the reference noise does not affect the resolution of the signal chain. This becomes very critical for high-precision systems such as medical imaging, precision weigh scales for chemical and pharmaceutical labs, seismic measurement equipment, and high precision test and measurement equipment where the ENOB of the system is greater than or equal to 20 bits. These systems typically use an active filter for high-frequency thermal noise; however, designing a low pass filter with less than 10 Hz cut-off frequency is impractical due to high capacitor requirement and slow response. Therefore these applications choose the reference with the best possible flicker noise for signal chain requirement. The accurate measurement is critical so that the designer is not constrained to over design the precision signal chain part and achieve faster system response.