Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

A Digitally-Controlled, Fractional-Bit, Pre-Emphasis Capability

IP.com Disclosure Number: IPCOM000127770D
Publication Date: 2005-Sep-13
Document File: 4 page(s) / 125K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that enables a serial data stream to transmit data with no pre-emphasis, a full-bit of pre-emphasis, or a half-bit of pre-emphasis. Benefits include improved signaling performance.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

A Digitally-Controlled, Fractional-Bit, Pre-Emphasis Capability

Disclosed is a method that enables a serial data stream to transmit data with no pre-emphasis, a full-bit of pre-emphasis, or a half-bit of pre-emphasis. Benefits include improved signaling performance.

Background

Some high-speed, serial signals such as USB 2.0 on have issues with the rise and fall times of the signals, which cause leading-edge data eye closures. Full-bit pre-emphasis was introduced to help overcome this; however, at USB2 speeds (480 Mbps), a full-bit wide pre-emphasis over-equalizes the losses in the data channel, and ends up longer than the bit transition times. Full-bit pre-emphasis causes an unnecessary overshooting of the signal.

General Description

The disclosed method enables a serial data stream to transmit data with no pre-emphasis, a full-bit of pre-emphasis, and a half-bit of pre-emphasis. Figures 1 and 2 show a reduced logic means for providing control of either the full-bit or half-bit pre-emphasis. No pre-emphasis is controlled by a pre-emphasis enable (pe_en) signal into the boost (pre-emphasis) output current driver. The current level in each current driver (i.e. main and boost) is controlled by the analog bias signals main_pbias and boost_pbias

The differences between the full- and half-bit pre-emphasis waveforms are shown in Figure 3 and Figure 4, respectively. Full-bit pre-emphasis is generated by inverting the data stream, then delaying it by a bit period. The disclosed method enables half-bit pre-emphasis by inverting the data stream, then delaying it only by a...