Marvell International Limited

Marvell Asia Pte., Ltd.

Supaket Katchmart

Henri Sutioso

David Liaw

Gregory Burd

Qiyue Zou

Pantas Sutardja

Mats Oberg

Li Zhang

Jerome F Richgels

David Sue-Hong Liaw

Hongying Sheng

Naim Siemsen-Schumann

Xinyang Yang

Sameer Vaidya

Vivek Khanzode

Pallavi Joshi

A method for cancelling, from servo signals read in a read channel while a write channel is active, interference caused by write signals in the write channel, includes generating a predicted channel response signal from the write signals in a data clock domain, resampling the generated predicted channel response signal using a clock in the data clock domain having a rate corresponding to a servo clock from a servo clock domain, transferring the resampled predicted channel response signal from the data clock domain to the servo clock domain and aligning phase of the transferred resampled predicted channel response signal with phase of the servo clock, determining a domain-boundary-crossing delay incurred in the transferring, based on the domain-boundary-crossing delay, synchronizing the phase-aligned transferred resampled predicted channel response signal with the servo signals, and subtracting the synchronized phase-aligned transferred resampled predicted channel response signal from the servo signals.

Write signal interference cancellation across data/servo clock boundary

A method of clocking a data channel of a storage device includes generating a single time-base frequency signal, deriving from the single time-base frequency signal, using a plurality of frequency-modification techniques, a plurality of individual clock signals, each respective one of the individual clock signals being for clocking a respective one of reading, writing and servo functions of the data channel. When the storage device is a disk storage device having a rotational frequency, generating a single time-base frequency signal may include generating a time-base frequency signal based on the rotational frequency. Deviation of the single time-base frequency from the rotational frequency may be detected, and the deviation may be compensated for. Each technique of the frequency-modification techniques may be a digital frequency-modification technique, such as a digital timing recovery technique or a digital frequency division technique.

Unified time base for storage device data channel

A method of reading servo wedge data from a rotating constant-density magnetic storage medium having a plurality of tracks, where each track is written at a track pattern frequency, the respective track pattern frequencies varying from a lowest frequency at an innermost one of the tracks to a highest frequency at an outermost one of the tracks, includes, for each respective track, determining, based on the pattern frequency of the respective track, a desired sampling position, sampling actual samples of servo wedge data based on a sampling clock used for all tracks, having a sampling frequency at least equal to the track pattern frequency of the outermost track, determining a phase relationship of the desired sampling position to the sampling clock, and, depending on the phase relationship between the sampling position and the sampling clock, interpolating a sample, or omitting interpolation of a sample and squelching the interpolation clock.

Digital timing recovery for constant density servo read operations

A method for writing repeatable run-out (RRO) data, to surfaces of a rotating magnetic storage medium in a storage device having two read channels, includes detecting, with a first head, using a first read channel, a servo sync mark (SSM) on a first track on a first surface, establishing a recurring servo-gating signal at a successive fixed interval from the SSM, detecting, with the first head, servo signals from the first track on occurrence of the recurring servo-gating signal, processing the servo signals from the first track, to generate first positioning signals for positioning the first head relative to the first track, following a similar procedure with a second read channel having a second head to generate second positioning signals for the second read head, and writing first and second RRO data to servo wedges of the first and second tracks according to the respective positioning signals.

Dual-surface RRO write in a storage device servo system

A storage device controller includes drive controller circuitry configured to control writing and fetching of data from a storage medium, read data channel circuitry for interfacing between the drive controller circuitry and the storage medium, test controller circuitry configured to test the read data channel circuitry by issuing test commands simulating the writing and fetching of data from the storage medium, and selector circuitry configured to switchably couple the read data channel circuitry to the drive controller circuitry in an operating mode and to the test controller circuitry in a testing mode. The storage device controller may include a pattern generator configured to output the test commands. Processor circuitry may be configured to store test results in memory, to compute performance metrics from the stored test results, and communicate the performance metrics to a host device.

United states test controller for system-on-chip validation

A method for writing repeatable run-out data, representing a recurring contribution to position error, to a rotating constant-density magnetic storage medium, includes repeating, for each respective track at a respective radius of the constant-density magnetic storage medium, (1) determining a respective track pattern frequency based on track location and desired data density, (2) locating a position in a respective servo wedge on the respective track based on servo sync mark detection, (3) writing the repeatable run-out data to the respective servo wedge at a time delay, from the location of the position in the respective servo wedge, that is inversely proportional to the respective radius, to achieve a predetermined offset, and (4) repeating the determining, the locating and the writing for each servo wedge on the respective track of the constant-density magnetic storage medium.

Write timing for RRO field in a constant density servo system

A self-servo-write (SSW) method in a storage device includes detecting, with a first read head, SSW spiral signals from a first track on a first storage medium surface, processing the SSW spiral signals from the first track using a first read channel, to generate first control signals for positioning the first read head relative to the first track, detecting, with a second read head, SSW spiral signals from a second track on a second storage medium surface, processing the SSW spiral signals from the second track using a second read channel, to generate second control signals for positioning the second read head relative to the second track, positioning a first write head relative to the first track using the first control signals via a single write channel, and positioning a second write head relative to the second track using the second control signals via the single write channel.

Dual-surface self-servo-write for storage device

Storage device self-servo-write includes generating a time base frequency signal, generating a sampled frequency signal by sampling the time base frequency signal at a sample rate to obtain a first set of samples, decimating those samples at a decimation rate to obtain a second set of samples at a spiral frequency of which the time base frequency is a first integer multiple, detecting a spiral track based on the spiral frequency, and writing a servo pattern based on the spiral track and the time base frequency. A generated sampled frequency obtained by sampling the time base frequency signal at the sample rate is used as the servo write frequency, of which the time base frequency is a second integer multiple. Alternatively, the time base frequency is multiplied by a first rational multiple so that the time base frequency is a second rational multiple of the servo write frequency.

Unified time base for self-servo-write operation

The present disclosure describes aspects of constant-density writing for magnetic storage media. In some aspects, a constant-density writer delays transitions between bits within write data to enable constant-density writing. The write data has an initial bit period based on a constant clock signal, which is generated based on the rotation of a media disk. The constant-density writer modifies the write data to generate phase-delayed write data, which has a bit period that is greater than or equal to the initial bit period. To realize this bit period, the constant-density writer changes write phases of bit transitions within the write data. The constant-density writer can also insert stretch bits, filter single-bit transitions, and mitigate glitches within the phase-delayed write data.

Constant-density writing for magnetic storage media

Zone self-servo write (SSW) technology is disclosed that leverages two clock signals synchronized in parallel to transition between zones to write servo patterns at different frequencies while minimizing error rate despite the different frequencies. Two separate clock signals ('clocks') are used to locate and lock to different reference spirals. By updating both clocks in parallel instead of in series, error rate for writing while stepping up frequency across zones is reduced.

Zone self servo writing with synchronized parallel clocks

This disclosure describes apparatuses and techniques for multi-channel servo demodulation. Multiple servo demodulation channels enable additional information to be obtained during the self-servo writing process, such as relative positions of multiple read heads and tracking of multiple servo patterns. This additional information enhances accuracy for self-servo writing and can lead to higher recording densities in media drives, and thus more storage with little or no additional cost.

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