Adaptive equalizer with large data rate range

An equalizer, comprising:

• an equalizer core coupled to an input signal from a transmission medium and a bandwidth control signal, wherein the equalizer core applies a transfer function to the input signal to compensate for losses incurred in the transmission medium and generates a core output signal, and wherein the bandwidth control signal controls a bandwidth of the transfer function;
• a slicer coupled to the core output signal that converts the core output signal to a digital output signal having a fixed digital output swing, wherein the fixed digital output swing approximates a swing of the input signal prior to transmission over the transmission medium;
• and
• an automatic gain control (AGC) loop coupled to the core output signal and the digital output signal that compares the core output signal with the digital output signal and generates the bandwidth control signal;
• wherein the AGC loop limits a bandwidth of the core output signal and the digital output signal and compares a band-limited core output signal with a band-limited digital output signal to approximate an energy difference;
• wherein the AGC loop also varies the bandwidth of the core output signal and the digital output signal as a function of the energy difference;
• wherein the equalizer core comprises:
• signal and generates a transfer function output signal;
• a variable low-pass filter coupled to the transfer function output signal and the bandwidth control signal, wherein the variable low-pass filter varies the bandwidth of the transfer function output signal and generates a filter output signal;
• and
• an adder coupled to the input signal and the filter output signal that generates the core output signal.

An equalizer, comprising:

• an equalizer core coupled to an input signal from a transmission medium and a bandwidth control signal, wherein the equalizer core applies a transfer function to the input signal to compensate for losses incurred in the transmission medium and generates a core output signal, and wherein the bandwidth control signal controls a bandwidth of the transfer function;
• a slicer coupled to the core output signal that converts the core output signal to a digital output signal having a fixed digital output swing, wherein the fixed digital output swing approximates a swing of the input signal prior to transmission over the transmission medium;
• and
• an automatic gain control (AGC) loop coupled to the core output signal and the digital output signal that compares the core output signal with the digital output signal and generates the bandwidth control signal;
• wherein the AGC loop limits a bandwidth of the core output signal and the digital output signal and compares a band-limited core output signal with a band-limited digital output signal to approximate an energy difference;
• wherein the AGC loop varies the bandwidth of the core output signal and the digital output signal as a function of a data rate of the input signal;
• wherein the equalizer core comprises:
• signal and generates a transfer function output signal;
• a variable low-pass filter coupled to the transfer function output signal and the bandwidth control signal, wherein the variable low-pass filter varies the bandwidth of the transfer function output signal and generates a filter output signal;
• and
• an adder coupled to the input signal and the filter output signal that generates the core output signal.

An equalizer, comprising:

• an equalizer core coupled to an input signal from a transmission medium and a bandwidth control signal, wherein the equalizer core applies a transfer function to the input signal to compensate for losses incurred in the transmission medium and generates a core output signal, and wherein the bandwidth control signal controls a bandwidth of the transfer function;
• a slicer coupled to the core output signal that converts the core output signal to a digital output signal having a fixed digital output swing, wherein the fixed digital output swing approximates a swing of the input signal prior to transmission over the transmission medium;
• and
• an automatic gain control (AGC) loop coupled to the core output signal and the digital output signal that compares the core output signal with the digital output signal and generates the bandwidth control signal;
• wherein the equalizer core is a multi-stage equalizer core having a plurality of individual equalizer core stage;
• wherein the AGC loop generates a plurality of individual-stage bandwidth control signals, and wherein each equalizer core stages comprises:
• a variable low-pass filter coupled to one of the individual-stage bandwidth control signals that varies the bandwidth of the transfer function.

A method of compensating for data rate variations in a digital equalizer, comprising the steps of:

• receiving an input signal from a transmission medium, wherein the input signal has a variable data rate;
• providing an equalizer core that applies a transfer function to the input signal to compensate for losses incurred in the transmission medium;
• varying a bandwidth of the transfer function to compensate for variations in the variable data rate of the input signal;
• providing a slicer that converts a core output signal from the equalizer core to a digital output signal having a fixed output swing that approximates a swing of the input signal prior to transmission over the transmission medium;
• isolating a first frequency range in the core output signal to generate a first band-limited signal;
• isolating a second frequency range in the digital output signal to generate a second band-limited signal;
• comparing the first band-limited signal with the second band-limited signal to generate a bandwidth control signal, wherein the bandwidth of the transfer function is varied in proportion to the bandwidth control signal;
• comparing the first band-limited signal with the second band-limited signal to generate a band-pass control signal;
• and
• varying the first frequency range and the second frequency range in proportion to the band-pass control signal.

A method of compensating for data rate variations in a digital equalizer, comprising the steps of:

• receiving an input signal from a transmission medium, wherein the input signal has a variable data rate;
• providing an equalizer core that applies a transfer function to the input signal to compensate for losses incurred in the transmission medium;
• providing a slicer that converts a core output signal from the equalizer core to a digital output signal having a fixed output swing that approximates a swing of the input signal prior to transmission over the transmission medium;
• isolating a first frequency range in the core output signal to generate a first band-limited signal;
• isolating a second frequency range in the digital output signal to generate a second band-limited signal;
• detecting a first energy-level in the core output signal;
• detecting a second energy-level in the digital output signal;
• comparing the first energy-level with the second energy-level to generate a single-stage gain control signal;
• varying a frequency dependant gain of the transfer function in proportion to the single-stage gain control signal;
• and
• varying the first frequency range and the second frequency range in proportion to the single-stage gain control signal.