Abstract: A wideband tunable (programmable) filter includes first-order and second-order filter circuits employing bipolar transistors. The bandwidth of the filter circuits are set by the product of the dynamic emitter resistance of the transistors and directly coupled on-chip capacitances. The filter bandwidth is inversely proportional to the time constant. To adjust the resonant frequency of the filter networks, emitter currents are varied, which in turn controls the emitter resistances. As the resonant frequency of the filter network is varied, the gain and normalized frequency response of the various output nodes remain constant. In the second-order configuration, the damping ratio of the filter is set using "positive" feedback, for a Q of greater than one-half, with a loop gain of less than one. Temperature compensation is accomplished by use of a temperature "dependent" voltage network.

Abstract: Methods and circuitry for generating sector and data cell timing frequencies for banded variable frequency sector disc drive systems with dedicated plus embedded servo positioning systems which have the timing signals synchronized to servo track information written on a dedicated surface of the disc.

Abstract: A method of correcting read channel signal compensation in magnetic storage data storage systems with calibration data stored on select portions of the magnetic recording medium.

Abstract: A method and apparatus for equalizing a signal with weighted first and second derivative signals extracted from a resistance-capacitance-inductance series circuit.

Abstract: A self-synchronizing servo control system and its associated servo data code for use in a high-density disk memory is disclosed. The servo data is formatted into a sync/index zone and a data zone. Sync and index di-bits are written only in the sync/index zone, while only servo data position di-bits are written in the data zone. Elimination of the sync and code di-bits used in prior art methods removes all requirements for radial phase coherence during the writing process, and increases the servo sample frequency. The new servo data code also reduces the intersymbol interference seen by adjacent pulses. The associated configuration of the servo control system is also disclosed.

Abstract: A variable gain amplifier system with a temperature stabilized exponential control signal input and wide range amplifier.