| 摘要 |
An apparatus (22) for reducing noise in a tracking error signal receives input signals from an array (5) of photodetectors, each input signal indicating the amount of laser light incident on the corresponding photodetector reflected from an optical disc. The input signals from diagonal pairs of photodetectors are summed and then filtered and digitized to produce a pair of digital input signals. A signal difference generator (20) produces first and second difference signals when either the first or the second digital input signals are received. The first and second difference signals are received by a programmable timing element having a user programmable device (41) and a signal limiting device (32, 33, 34, 35) for limiting the duration of the first or second difference signals provided at respective first or second outputs of the programmable timing element to a user programmable maximum value. The duration limited first or second difference signals are coupled to a charge pump (38) to provide a tracking error signal at an output.
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