Suppression of Limit Cycles in Digital Filters

The injection of randan dither to suppress limit cycle oscillations in second-order direct form digital filter sections is discussed. Three types of dither signal are used: uniformly distributed random dither, binary randan dither and bandstop dither. All the limit cycles in the second-order filter sections can be suppressed by the injection of any one of three dither signals. No remaining noise appears in the output from the filter in the zero-input condition. Experimental comparisons are made of the average time taken to suppress limit cycles and of the increase in output noise caused by the dither. With binary random dither, the time to suppress a limit cycle is comparable with the time for zero-input response ofa linear filter to decay below the quantization threshold. Bandstop dither has the advantage to suppress limit cycles about as quickly as binary dither yet it causes an increase in output noise of lessthan 2 GB.

Name dc:type.qualificationname

masters

Level dc:type.qualificationlevel

masters

Grantor dc:publisher.institution

Aston University

Year dc:date.issued

1982

Author dc:creator

• Liu, Hou-Ming

DOI dc:identifier.doi

https://doi.org/10.48780/publications.aston.ac.uk.00008228

OAI identifier oai:identifier

oai:publications.aston.ac.uk:8228