ADAPTIVE CABLE EQUALIZER FOR DIGITAL COMMUNICATION

• US 20170033957A1
• Filed: 07/28/2016
• Published: 02/02/2017
• Est. Priority Date: 07/28/2015
• Status: Abandoned Application

• Current Assignee: Wanpeng Cao
• Original Assignee: Wanpeng Cao
• Inventors: Cao, Wanpeng
• Application Number:
  US15/221,601
• Publication Number:
  US 20170033957A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 3/45206 Folded cascode stages
• CPC Class Codes: H04L 25/03885 adaptive
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005

Abstract

A single stage cable equalizer with a differential input stage, a source degeneration RC network and a folded cascode output stage achieves the inverse transfer function of a cable with a 1st order attenuation. The equalizer can be made adaptive by tuning the design parameters of the equalizer, such as source degeneration capacitor C in a feedback loop configuration. Multiple single stage equalizers can be cascoded to equalize the cable with a higher order attenuation.

Claims

1. An adaptive 1st order cable equalizer circuit implementation comprising:

a differential input stage configured to receive the input signal;

a folded cascode stage to reduce the miller effect of input stage to increase the bandwidth of equalizer;

a source degeneration RC network to provide the desired equalization frequency response.

2. The equalizer circuit of claim 1 wherein the input differential pair is a transistor pair such as MOS transistor or BJT transistor.

3. The equalizer circuit of claim 1 wherein the folded cascode stage is formed by cascode MOS transistor or BJT transistor to improve the bandwidth of equalizer.

4. The equalizer circuit of claim 1 wherein the input degeneration RC network is formed by resistor and capacitor in parallel configuration.

5. The RC degeneration network of claim 4 wherein R and C are integrated on chip or connected outside off chip.

6. A method of adaptively adjusting the equalizer transfer function by tuning the design parameters of the equalizer circuit to match its transfer function to the inverse transfer function of the cable.

7. The method of claim 6 wherein the tunable parameters are input differential pair trans-conductance Gm, source degeneration resistor Re, source degeneration capacitor C and loading resistor Ro.

8. The method of claim 6 wherein cascading multiple 1st order equalizers to achieve a higher order overall transfer function to equalize the frequency response of the cables with higher order attenuations.