Abstract:
PROBLEM TO BE SOLVED: To provide a sample and hold circuit suitable for mixed signal processing. SOLUTION: A sample and hold circuit includes a sampling capacitor for storing a sample of an input signal, an output stage for outputting the sample stored on the sampling capacitor, and input circuitry for sampling the input signal and storing the sample on the sampling capacitor. The input circuitry includes an autozeroing input buffer which selectively samples the input signal during a first operating phase and holds a sample of the input signal during a second operating phase. The autozeroing input buffer cancels any offset error. The input circuitry also includes switching circuitry for selectively coupling the sampling capacitor with an input of the sample and hold circuitry during the second operating phase and to an output of the autozeroing input buffer during the first operating phase. COPYRIGHT: (C)2008,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a sync mark detection method that uses information from a preamble and the sign of sampled data in order to further increase the fault tolerance of a sync mark detector. SOLUTION: Digital data comprise a preamble field followed by a sync mark followed by a data field. Timing recovery (28) in a read channel synchronizes to a phase and frequency of the preamble field and a sync detector (A120) detects the sync mark in order to frame operation of an RLL decoder (36, A122) for decoding the detected data field. To decrease the probability of early misdetection, the sync mark is chosen to have minimum correlation with shifted versions of the sync mark concatenated with the preamble field. To further increase the fault tolerance, the sync mark detector is enabled by timing recovery relative to the end of the preamble field. COPYRIGHT: (C)2007,JPO&INPIT