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Negative Feedback Method To Reduce Overshooting and Bounce For ATA Driver by Gate Monitoring

IP.com Disclosure Number: IPCOM000010979D
Original Publication Date: 2003-Feb-06
Included in the Prior Art Database: 2003-Feb-06
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Abstract

a negative feedback method to reduce overshooting and bounce for ATA driver by gate monitoring

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  Negative Feedback Method To Reduce Overshooting and Bounce For ATA Driver by Gate Monitoring

  Disclosed is a negative feedback method to reduce overshooting and bounce for ATA driver by gate monitoring.

  The slew rate of an HDD AT bus driver is selected to match a transfer mode, and a kind of flat cable. In general a higher slew rate creates a bigger margin for the setup/hold time, but causes serious overshooting and bounce noise for some data patterns, so it ultimately reduces the setup/hold time.

  My previous research disclosure (JP820000909) shows that a negative feedback method can work to produce a higher slew rate and a lower noise level. However it has a problem when the driver starts from a high impedance condition. .This research disclosure shows an additional method to solve the problem by monitoring the gate voltage.

  In the previous method the driver monitors the output voltage level, and dynamically controls the gate voltage of the output FET. The 1st phase (rise: 0V to 1/2Vdd330, fall: Vdd330 to 1/2Vdd330) is the capability of a normal drive. The 2nd phase (rise: 1/2Vdd330 to 3/4Vd330, fall: 1/2Vdd330 to 1/4Vdd330) is the capability of a braked drive (the gate voltage is held constant). The 3rd phase (rise: 3/4Vdd330 to Vdd330, fall: 1/4Vdd330 to GND) is the capability of a boosted drive (it is stronger than the normal drive). If the driver starts from GND or Vdd330, it leads to a higher slew rate and a lower noise level, but if it starts from the 2nd phase, the gate voltage of the output PFET is higher than the threshold voltage of the FET, this is in a brake mode, so it ho...