In addition to the multi-stage decimation filters for out-of-band attenuation, the TLV320ADCx140/TLV320ADCx120/PCMx120-Q1/PCMx140-Q1 devices also support digital bi-quad filters for in-band frequency shaping. For example, in noise cancellation or equalization, the signal band of interest is usually less than a few 100 Hz. Using programmable digital bi-quad filters, the filter parameters can be configured to suppress undesirable audio signals prior to any digital processing. These filters can be used as low-pass, high-pass, band-pass, or band-reject filters. For additional information on bi-quad filter configuration, refer to the TLV320ADCx140 Programmable Bi-quad Filter Configuration and Applications, application note.