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Negative Feed Back Methodology To Reduce Overshooting and Bounce For ATA Driver

IP.com Disclosure Number: IPCOM000014174D
Original Publication Date: 2002-Feb-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 5 page(s) / 69K

Publishing Venue

IBM

Abstract

Disclosed is a Negative Feed Back Methodology To Reduce Overshooting and Bounce For A TA Driver .

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  Negative Feed Back Methodology To Reduce Overshooting and Bounce For ATA Driver

      Disclosed is a Negative Feed Back Methodology To Reduce Overshooting and Bounce For ATA Driver.

      In current design a slower slew rate driver is used to reduce overshooting and bounce. But a slower slew rate reduces a setup/hold time margin. This method is able to have higher slew rate and lower level noise of overshooting and bounce.

ATA cable is a flat cable, has mutual coupling characteristic.It causes crosstalk noise at simultaneous and alternative switching. This driver has 4 kinds of slew rate to meet a several frequency transfer modes.

This circuit controls dynamically the output slew rate.

The 1st phase(Rise : 0v to 1/2Vdd330, Fall : Vdd330 to 1/2Vdd330) is normal drive, the 2nd phase(Rise : 1/2Vdd330 to 3/4Vdd330, Fall : 1/2Vdd330 to 1/4Vdd330) is braked drive(the gate voltage is kept), and the 3rd phase(Rise : after 3/4Vdd330, Fall : after 1/4Vdd330) is boosted drive(higher slewrate).

Figure 1 shows the block diagram.

PAD(output) goes through Low Pass Filter to reduce high frequency noise, this circuit monitors PAD_R voltage level.

Figure 2 shows the detail circuit of PrePD(pre driver of pull-down driver).

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PAD_R goes down to 1/2Vdd330, then driving of PDGATE stop. Output slew rate is down, so crosstalk noise at simultaneous and alternative

switching become weak.

PAD_R goes down to 1/4Vdd330, after some del...