Multistage tuning-tolerant equalizer filter with improved detection mechanisms for lower and higher frequency gain loops
First Claim
1. An equalizer filter for compensating a received distorted signal for frequency dependent signal modifications introduced by a transmission channel, the received signal having an amplitude, said filter comprisingat least one amplifying compensation stage having a gain and a saturation level,at least one limiting amplifier,gain control means for controlling the gain of the at least one amplifying compensation stage, the gain control means comprising a plurality of comparator circuits comparing filtered input and output signals of the limiting amplifier, the plurality of comparator circuits comprising a bias current source,wherein the bias current source is adapted to deliver a variable current and the bias current is increased during periods when voltage levels of signals to be compared are the highest.
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Abstract
The present invention provides an equalizer filter for compensating a received distorted signal for frequency dependent signal modifications introduced by a transmission channel, the received signal having an amplitude. The filter comprises at least one amplifying compensation stage having a gain and a saturation level, at least one limiting amplifier, and gain control means for controlling the gain of the at least one amplifying compensation stage, the gain control means comprising at least one comparator circuit comparing filtered input and output signals of the limiting amplifier, the at least one comparator circuit comprising a bias current source. The bias current source is adapted to deliver a variable current.
22 Citations
21 Claims
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1. An equalizer filter for compensating a received distorted signal for frequency dependent signal modifications introduced by a transmission channel, the received signal having an amplitude, said filter comprising
at least one amplifying compensation stage having a gain and a saturation level, at least one limiting amplifier, gain control means for controlling the gain of the at least one amplifying compensation stage, the gain control means comprising a plurality of comparator circuits comparing filtered input and output signals of the limiting amplifier, the plurality of comparator circuits comprising a bias current source, wherein the bias current source is adapted to deliver a variable current and the bias current is increased during periods when voltage levels of signals to be compared are the highest.
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16. A method for compensating a distorted signal for frequency dependent signal modifications introduced by a transmission channel, the signal having an amplitude, the method comprising
receiving a distorted signal, compensating said distorted signal outputting a compensated signal at an output node of an equalizer filter, wherein the step of compensating comprises providing a gain, amplifying the received signal in at least one amplifying compensation stage using the provided gain, comparing differential outputs of a first signal on an output node of the last amplifying compensation stage and of a second signal on the output node of the equalizer filter, the comparing being adapted so that comparison performance is increased during periods when voltage levels of signals to be compared are the highest by increasing bias current of a comparator circuit.
Specification