摘要:
A disk driver writer precompensation system modulates the write current waveform based on a pattern of data bits magnetically recorded on a medium in order to adjust the timing of magnetic transitions recorded on the medium.
摘要:
A pulse-mode data writing protocol is disclosed which reduces the time required to implement a transition in the direction of magnetization of a recording medium, and which reduces the total power required to encode a given data sequence. After a magnetic transition is encoded on the medium by generating a write current pulse through the write head, the write current through the recording head is reduced, thereby utilizing the spatial extent of the write bubble to encode the lack of a transition on the medium. Alternate configurations are disclosed for various scenarios of write bubble size versus maximum cell size, all utilizing the principle of the invention.
摘要:
A write driver circuit selectively provides a write current through a write head in first and second opposite directions. The write driver circuit is connected to the write head through an interconnect. The write driver circuit provides an incident write current signal through the interconnect to the write head, and also provides a reflection cancellation signal through the interconnect to the write head. In an exemplary embodiment, the incident write current signal is provided by providing an incident voltage signal across the write head, and the reflection cancellation signal is provided by providing a reflection cancellation voltage signal across the write head. In an exemplary embodiment, the reflection cancellation signal is a delayed and filtered version of the incident write current signal that cancels a reflected signal that is reflected at the interface between the interconnect and the write head due to impedance mismatching.
摘要:
A write driver circuit selectively provides write current through a write head in first and second opposite directions. First and second active devices are driven with first and second pre-drive signals. Third and fourth active devices are driven with third and fourth pre-drive signals. First and second pull-up resistances are provided respectively between the first and second active devices and a fixed voltage, and third and fourth pull-up resistances are provided respectively between the third and fourth active devices and the fixed voltage. A first capacitor is connected between the first active device and an intermediate point of the third pull-up resistance, and a second capacitor is connected between the second active device and an intermediate point of the fourth pull-up resistance.
摘要:
A preamplifier system is connected through an interconnect to a read head. The preamplifier system includes a voltage-sense preamplifier having at least one input connected through the interconnect to the read head and having at least one output, and also includes a current-sense preamplifier having at least one input connected through the interconnect to the read head and having at least one output. A summing circuit is connected to combine the outputs of the voltage-sense preamplifier and the current-sense preamplifier. For optimal performance, the preamplifier system is impedance matched to the interconnect. The preamplifier system achieves excellent response due to impedance matching with acceptably low noise levels, since the correlated noise associated with the current-sense preamplifier is canceled at the summing circuit.
摘要:
A write driver for an inductive load includes load terminals for connection to an inductive load, and a driver circuit responsive to first and second control signals to supply a drive current through the load in respective first and second directions. A voltage-mode H-bridge connected to the load terminals is operable to selectively supply a voltage across the load terminals and head. Program means operates the voltage-mode H-bridge for a predetermined time period following initiation of the respective first and second control signal to provide a voltage across the load terminals which quickly raises the write current to a steady state condition. Ringing is suppressed by employing an impedance-matched H-bridge for the driver circuit, the impedance-matched H-bridge having an impedance matched to the impedance of a transmission line connecting the load to the terminals.
摘要:
A power supply filter has a primary current source coupled to a node carrying a power supply signal. The second end of the primary current source is coupled to an impedance that is further coupled to a low voltage node. A differential amplifier having an inverting input, a non-inverting input, and an output, has its non-inverting input coupled to the junction between the impedance and the primary current source. The output of the differential amplifier carries the filtered power supply signal and is coupled to a capacitance. The capacitance is coupled between the output and a lower voltage. A feedback path is coupled between the output and the inverting input.
摘要:
A power supply filter is constructed with a capacitive element and an active element coupled to a filtered node and an impedance coupled between the filtered node and a power supply node. The filtered node for carrying a filtered version of a power supply signal on the power supply node. The active element having electrical characteristics such that the addition of the active element to the power supply filter reduces the amount of capacitance needed from the capacitive element to achieve a desired pole frequency for a given voltage drop across the impedance element.
摘要:
A preamplifier circuit is connected to a transducing head, and has integrated bias circuitry and offset recovery circuitry. The offset recovery circuitry is activated in response to a transition from write mode to read more to provide an output signal representative of a signal across the transducing head. The bias circuitry is driven by the output signal of the offset recovery circuitry to bias the transducing head.
摘要:
A write circuit selectively provides a write current through a write head in first and second opposite directions. The write circuit is connected to the write head by an interconnect, and has a positive supply level and a negative supply level. A first voltage source provides a first control voltage, and a second voltage source provides a second control voltage. A first resistor is provided between the first voltage source and the interconnect for impedance matching to the interconnect, and a second resistor is provided between the second voltage source and the interconnect for impedance matching to the interconnect. The first and second control voltages provide a transient voltage to the interconnect and provide a subsequent steady-state voltage to the interconnect.