Patent ID: 7415064

Claim:
An equalizer, comprising: an equalizer core coupled to an input signal from a transmission medium and a gain control input, where the equalizer core applies a frequency dependant gain to the input signal to generate a core output signal, and wherein the frequency dependant gain is controlled by the gain control input and compensates for losses incurred in the transmission medium; a fixed-swing slicer coupled to the core output signal that converts the core output signal to a digital output signal having a fixed digital output swing; and a control loop coupled to the core output signal and the digital output signal that normalizes the core and digital output signals with respect to their low-frequency energy levels, compares the normalized core output signal with the normalized digital output signal to approximate a normalized energy level difference, and generates the gain control input; a first low-band-pass filter coupled to the core output signal that generates a low-frequency core output; a second low-band-pass filter coupled to the digital output signal that generates a low-frequency digital output; a first high band-pass filter coupled to the core output signal that generates a high-frequency core output; a second high-band-pass filter coupled to the digital output signal that generates a high-frequency digital output; a first envelope detector coupled to the low-frequency core output that generates a first energy-level signal; a second envelope detector coupled to the low-frequency digital output that generates a second energy-level signal; a third envelope detector coupled to the high-frequency core output that generates a third energy level-signal; a fourth envelope detector coupled to the high-frequency digital output that generates a forth energy-level signal; a first multiplier that multiplies the first energy-level signal with the fourth energy-level signal to generate a first normalized signal; and a second multiplier that multiplies the second energy-level signal with the third energy-level signal to generate a second normalized signal; wherein the control loop compares the first normalized signal with the second normalized signal to generate the gain control input.