Abstract: There is described a method for controlling the sensitivity profile of a photodetector (1; 1a to 1d) comprising at least one well (10; 10a to 10d) of a first conductivity type (e.g. N) formed in a semiconductor substrate (20) of a second conductivity type (e.g. P), this method comprising the steps of determining a desired sensitivity profile for the photodetector, forming at least one diffusion region (15; 15a to 15d) of the first conductivity type in a determined region of the well and/or forming at least one diffusion region (25) of the second conductivity type in the semiconductor substrate adjacent to the well, and connecting said at least one diffusion region of the first or second conductivity type to a positive or negative potential of a reverse-bias voltage applied across said well and said semiconductor substrate.

Abstract: An apparatus and method for filtering intersymbol interference from an information signal generated from a storage medium. This apparatus utilizes a delay line, gain devices, summing devices, and has specified transfer functions. Furthermore, this apparatus and method can make real time adjustments in order to maintain an optimal level of filtering.

Abstract: An improved method and circuitry for processing high-impedance (current mode) input signals for use in translinear and other mode circuits in a manner that avoids the signal dependent bandwidth variations that occur in the prior art. A non-linear feedback structure using a transconductance gain element is employed to extend the bandwidth and/or suppress bandwidth variations encountered in the prior art. One application of this invention is the extension of Gilbert amplifier topologies, with their attendant normalization and integrated circuit implementation advantages, for operation with very low input signal levels to high bandwidth applications. A further extension in this invention allow this transconductance to be electrically adjusted to allow active bandwidth control or to compensate for signal sources with different input capacitances. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals.

Abstract: An improved method and circuitry for amplifying and processing detected pairs of input signals, in a manner that provides excellent DC accuracy, wideband signal handling capability and fast overload recovery, are disclosed. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals. Common base and emitter coupled circuits are arranged in various configurations to simultaneously process pairs of detected signals to provide normalized analog differential output current signals that can be directly used by amplifier circuits without concern for overloading of the amplifier as a result of severe overload signals detected by the input sensors. The circuitry readily accommodates external real-time gain control.

Abstract: A system for providing a security capability for an electronic information reproducing device mounted within a housing, such as a floppy disk mounted in a jacket or a tape in a 3480 tape cartridge, by attaching an electronic surveillance tag to an inner surface of the housing during its manufacture so that the electronic surveillance tag cannot be easily removed from within the floppy disk or 3480 tape cartridge without destroying it and is not visible from outside of the housing and an electronic drive means having an electronic circuit for detecting the presence or absence of an electric surveillance tag and generating a signal in response to such presence or absence.