摘要:
A method for deriving precise control over laser power of an optical pickup unit (OPU) includes: providing an analog-to-digital converter (ADC) within an automatic power calibration (APC) circuit to derive a path gain and/or a path offset from the APC circuit; and selectively performing compensation according to the gain and/or the path offset, in order to maintain precision of a relationship between the laser power and a target command utilized for controlling the laser power. An associated APC circuit comprising an ADC and at least one compensation module is further provided. The ADC is utilized for deriving a path gain and/or a path offset from the APC circuit. The compensation module is utilized for selectively performing compensation according to the path gain and/or the path offset, in order to control the laser power by a target command.
摘要:
An apparatus and method of generating a zero crossing signal for an optical disc drive to reduce width deviation due to sampling effect, thereby improving servo control and detection. An embodiment of the apparatus comprises a reshaping device receiving a first digital servo signal of the optical disc drive to upsample the first digital servo signal data, thereby generating a second digital servo signal with higher resolution than the first digital servo signal; and a servo control-and-detection device receiving and slicing the second digital servo signal to generate a servo zero crossing signal.
摘要:
An apparatus of processing an input signal generated according to accessing of an optical storage medium is disclosed. The apparatus has a detecting circuit and a decision logic. The detecting circuit is coupled to the input signal for detecting a target peak value and a target bottom value of the input signal within a time period, wherein the time period is not less than a period of a reference signal generated according to accessing of the optical storage medium. The decision logic is coupled to the detecting circuit for determining a reference level according to the target peak value and the target bottom value.
摘要:
A speed control device, which is adapted to be used in connection with a derailleur type bicycle or an internal gear hub type bicycle, has one operation mode for up-shifting the speed and another operation mode for down-shifting the speed. The two operation modes can be affected by an operation lever, with the operation lever pivoted in a second rotation direction for the up-shifting operation and in a first rotation direction for the down-shifting operation.
摘要:
A method for deriving precise control over laser power of an optical pickup unit (OPU) includes: providing an analog-to-digital converter (ADC) within an automatic power calibration (APC) circuit to derive a path gain and/or a path offset from the APC circuit; and selectively performing compensation according to the gain and/or the path offset, in order to maintain precision of a relationship between the laser power and a target command utilized for controlling the laser power. An associated APC circuit comprising an ADC and at least one compensation module is further provided. The ADC is utilized for deriving a path gain and/or a path offset from the APC circuit. The compensation module is utilized for selectively performing compensation according to the path gain and/or the path offset, in order to control the laser power by a target command.
摘要:
A trimmer circuit is so configured that an electronic device will break down to produce a high current to trim a fuse. The electronic device is selectively configured to have a breakdown voltage lower than an applied voltage, for the trigger of its breakdown to be controllable. In an embodiment, the electronic device is switched between two states having two breakdown voltages respectively, and the applied voltage is higher than one of the breakdown voltages and lower than the other one.
摘要:
The invention provides an apparatus for controlling servo signal gains of an optical disc drive. The apparatus adjusts the gains of a plurality of servo signals controlling a servo system of the optical disc drive according to a closed-loop mode or a state-reloading mode whenever the optical disk drive encounters an operating state transition. In closed-loop mode, at least one AGC loop of the apparatus compensates the gains of the servo signals with a selectable bandwidth during a specific period after the operating state transition to accelerate the convergence of the servo signals. In state-reloading mode, at least one AGC loop of the apparatus reloads the previously saved convergence values or pre-determined values as the initial values according to the current operating state immediately after the operating state transition to accelerate the convergence of the servo signals.
摘要:
A digital to analog converter for converting a digital input signal provided by a host to an analog output signal includes a modulator receiving the digital input signal, modulating the digital input signal, and outputting a modulated signal, and a filtering circuit receiving the modulated signal, low pass filtering the modulated signal, and outputting the analog output signal to an output node. The filtering circuit includes a first switching circuit for adjusting the bandwidth of the filtering circuit according to a bandwidth switching signal.
摘要:
An automatic power control system, a down sampling circuit and a down sampling method. The automatic power control system is incorporated in an optical disc drive comprising a laser diode for receiving a control signal to generate a laser beam; and a photodetector for detecting the laser beam to generate an analog input signal. The automatic power control system comprises an analog-to-digital converter, a down sampling circuit, a comparator, and a digital-to-analog converter. The analog-to-digital converter converts the analog input signal to digital data. The down sampling circuit, coupled to the analog-to-digital converter, comprises a down sampler, a counter, and a controller. The down sampler receives a predetermined amount of digital data to generate representation data. The counter, coupled to the down sampler, calculates the amount of digital data, and resets the down sampler when the amount equals or exceeds the predetermined count. The controller, coupled to the counter, disables the counter when the digital data is invalid. The comparator, coupled to the down sampling circuit, compares the representation data with predetermined target data to generate error data. The digital-to-analog converter, coupled to the comparator, converts the error data to analog to generate the control signal.
摘要:
A high pass filtering device for an optical disc drive comprises a first low pass filter (LPF) of a first sampling rate, filtering a digital input signal; a down-sampler receiving a first filtered signal form the first LPF to down-sample the first filtered signal by an integer factor N; a second LPF of a second sampling rate, filtering a first down-sampled signal from the down-sampler, wherein the second LPF has a corner frequency corresponding to a desired frequency of the high pass filtering device, and the second sampling rate is equal to 1/N times the first sampling rate; an up-sampler receiving a second filtered signal from the second LPF to up-sample the second filtered signal by the factor N; and a subtractor subtracting an up-sampled signal output by the up-sampler from the digital input signal when the filter frequency is below a threshold frequency.