Patent ID: 7161981

Claim:
A decision feedback equalizer device having: a linear equalizer stage, which has at least one first digital filter with an adjustable first set of coefficients; and a decision feedback equalizer stage, which is connected downstream of the linear equalizer stage and has: a summer, to which an output signal of the linear equalizer stage is fed; a decision unit, to which an output signal of the summer is fed; and a decision feedback equalizer, to which an output signal of the decision unit is fed and which has at least one second digital filter with an adaptively adjustable second set of coefficients and which supplies an output signal, which is fed to the summer; the first set of coefficients comprising a first adjustable portion arranged behind a main coefficient, and a second adaptively adjustable portion extending up to the main coefficient; the first digital filter being fed a first error signal as a control signal for the setting of the first portion of the first set of coefficients and a second error signal as a control signal for the setting of the second portion of the first set of coefficients, which are in each case derived from the decision feedback equalizer stage; the second error signal being formed by a difference forming device from a difference between the input signal and the output signal of the decision unit; wherein first error signal is formed by an average value forming device, to which the second error signal is fed; the first digital filter has a coefficient setting device for setting the first portion of the first set of coefficients, which defines three states depending on the value of the first error signal, in which case the average value of the second error signal is greater than a first predetermined threshold value in the first state, the average value of the second error signal lies between the first predetermined threshold value and a second predetermined threshold value in the second state, and the average value of the second error signal is less than the second predetermined threshold value in the third state, and the coefficient setting device performs the setting in a manner dependent on the present state.