1. An apparatus comprising: a circuit including a filter configured to: update one or more adaptive coefficients of the filter based on an error signal; update a constrained coefficient of the filter based on the one or more adaptive coefficients, the constrained coefficient and a desired value, the update of the one or more adaptive coefficients of the filter not based on the desired value; and generate a sample of a sample sequence based on the one or more adaptive coefficients and the updated constrained coefficient, the error signal being based on the sample sequence.