SBAA378B November   2019  – December 2023 PCM3140-Q1 , PCM5140-Q1 , PCM6140-Q1 , TLV320ADC3140 , TLV320ADC5140 , TLV320ADC6140

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Infinite Impulse Response Filters
    1. 2.1 Digital Biquad Filter
  6. 3  TLV320ADCx140/PCMx140-Q1 Digital Biquad Filters
    1. 3.1 Filter Design Using PurePath™ Console
      1. 3.1.1 Example Generating Programmable Biquad Coefficients Using PurePath Console
    2. 3.2 How to Generate N0, N1, N2, D1, and D2 Coefficients with a Digital Filter Design Package
    3. 3.3 Avoid Overflow Conditions
    4. 3.4 Digital Biquad FiIter Allocation to Output Channel
    5. 3.5 Programmable Coefficient Registers for Digital Biquad Filters 1–6
    6. 3.6 Programmable Coefficient Registers for Digital Biquad Filters 7–12
  7. 4 How to Program the Digital Biquad Filters on TLV320ADCx140/PCMx140-Q1
  8. 5 Typical Audio Applications for Biquad Filtering
    1. 5.1 Parametric Equalizers
  9. 6 Crossover Networks
  10. 7 Voice Boost
  11. 8 Bass Boost
  12. 9 Removing 50 Hz–60 Hz Hum With Notch Filters
  13. 10Revision History
  14. 11Digital Filter Design Techniques
    1. 11.1 Analog Filters

3.3 Avoid Overflow Conditions

When cascading several biquad filters that gain the signal, make sure the overall response of the system does not cause the system to overflow. The biquads are computed in 32-bit fixed point arithmetic. If the overall response of the system in conjunction with the input signal is too large, undesired results can result due to arithmetic saturation. If saturation or overflow occurs, scale the input signal or scale down the coefficients of one or more biquads to keep the overall response of the system from saturating or overflowing.

Note that the overall response of the system is dependent on all the enabled components of the signal chain. The Digital High-Pass filter changes the frequency response at the low frequencies in conjunction with the Digital Biquad Filter response since both of these filters are cascaded together.