Abstract: A high fidelity hearing aid amplifier is operable at a very low battery voltage and includes a single integrated circuit chip which provides a variable gain amplifier and gain control circuitry operative at low signal levels to enhance gain at higher frequencies relative to gain at lower frequencies, such circuitry including a logarithmic rectifier arrangement and a peak detector in a compression ratio control circuit. Operation at a low battery voltage is enhanced through a compression ratio control circuit which provides a level shift between an AC output of the logarithmic rectifier arrangement and the peak detector. Current mirrors are provided to obtained balanced and stable operation, and an arrangement is provided for manual control by a user to obtain an optimum response characteristic.

Abstract: A method is disclosed for forming a shorting contact for shorting P-type and N-type conductivity regions in a semiconductor together. In one embodiment of this method, the P-type region is substantially a square and is surrounded by the N-type region. A substantially square contact opening is made to expose the P-type region and a portion of the N-type region. Sides of the contact opening are formed to be at substantially 45 degree angles with respect to sides of the substantially square P-type region. In this manner, the alignment tolerance for forming the contact opening is less critical than if the sides of the contact opening were parallel to the sides of the P-type region. The contact opening is then filled with a conductive material to electrically short the P-type region to the N-type region. The conductivity types in this example may be reversed.

Abstract: A diamond-shaped short contact overlapping two differing conductivity regions in a semiconductor. The shape and orientation providing maximum alignment tolerances for a given size of contact opening.

Abstract: An electronic circuit, suitable for use in a digital-to-analog converter, wherein a ladder network is provided to obtain a 2:1 successive reduction in the amount of current flow through successive shunt arms of the ladder network. The ladder network includes a plurality of serially coupled resistance means, at least a portion thereof comprising a resistor and a serially coupled transistor, and a plurality of shunt coupled resistors disposed in the shunt arms of the ladder network. A plurality of pairs of switching transistors, each pair thereof being adapted for coupling to a pair of complmentary switching signals produced in response to a bit of the digital word being converted, each one of the shunt resistors being coupled to a corresponding one of the pairs of switching transistors.

Abstract: A semiconductor voltage reference device formed by ion implanting particles into a semiconductor body having first and second doped regions of opposite type conductivity formed therein. Such particles are implanted with a peak concentration at a predetermined depth from a surface of the body, providing a third region of conductivity type opposite that of the first region and having a doping concentration greater than that of the second region. The particles extend beneath the surface of the body into the first and second regions, a junction being formed between the first and third regions beneath the surface of the body. Electrodes are provided in ohmic contact with the first and second doped regions. When the junction is reverse biased by applying a proper voltage across the electrodes the junction breaks down beneath the surface of the body establishing a fixed or reference voltage between the electrodes.