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Notch Filter with Fast Transient Response

IP.com Disclosure Number: IPCOM000104637D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Kisaka, M: AUTHOR [+2]

Abstract

This article describes an improvement over a conventional notch filter to obtain fast transient response. An analog notch filter uses capacitors to obtain specified frequency characteristics. Since capacitors require charge up time, a transient response time becomes slower than that of a circuit without capacitors. For a seek operation of a hard disk drive, it is important to have fast transient response during acceleration. For deceleration and track following, it is important to activate notch filters to suppress mechanical resonance. Therefore, capability of turning on/off the fast transient mode is also required.

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Notch Filter with Fast Transient Response

      This article describes an improvement over a conventional notch
filter to obtain fast transient response.  An analog notch filter
uses capacitors to obtain specified frequency characteristics.  Since
capacitors require charge up time, a transient response time becomes
slower than that of a circuit without capacitors.  For a seek
operation of a hard disk drive, it is important to have fast
transient response during acceleration.  For deceleration and track
following, it is important to activate notch filters to suppress
mechanical resonance.  Therefore, capability of turning on/off the
fast transient mode is also required.

      The drawing shows the present improvement wherein a twin-T type
notch filter is illustrated.  Two switches 1, 2 and three resisters
3, 4, 5 are added to the filter.  Switches 1 and 2 are turned on or
closed during acceleration to thereby faster charge capacitors with
an input voltage.  Therefore, output of the filter becomes almost
equal to the input voltage in a short time so that faster movement of
an actuator can be obtained.  Resister 5 is inserted to limit the
current from the input source.  This improvement may be used for
other types of filters that use capacitors.