International Business Machines Corporation

Francois X Delaporte

Gerard M Lebesnerais

Jean-Paul J Nuez

Daniel Ballatore

Jean-Pierre Pantani

Robert M Hornung

Anne-Marie Lamouroux

Daniel Azzis

An interface circuit for exchanging digital signals between two pieces of data processing equipment is provided in integrated form in accordance with international standards, such as EIA Standards. This is achieved through modification of an operational amplifier to adapt its use to the conditions and requirements of interface circuits.

Interface circuit in conformity with EIA standards and implemented with

Arrangements are described for correcting the voltage coefficient of resistance (VCR) of resistors integral with a semiconductor body and, more particularly, for correcting the VCR of resistors implanted in a semi-conductor body. Resistors typically comprising a resistive region of a first conductivity type formed in an isolated layer of opposite conductivity type which isolated layer, in general, includes an epitaxial layer passivated by a dielectric layer. A metal layer is formed on the dielectric layer and covers, at least partially, the resistive layer. The metal layer is brought to a suitable potential to produce opposite variations in the resistance with respect to variations created by the epitaxial layer.

Arrangement for correcting the voltage coefficient of resistance of

This invention relates to a digital to analog converter in general and specifically to unitary or monolithic miniature digital to analog converters designed to be fully embodied on a single one-half inch module without requiring external converter components. The digital to analog converter comprises n binary current sources and n two-way switches, n being the number of input word bits. Each switch is driven by a bit input and its function is to steer the current of the corresponding source either into a summing line for output or into a dump line. A primary feature of this converter is the separation of all individual bit converter structures comprising a current source and steering means into two different groups. In this scheme, a first group of converter structures is used to convert the high order bits and a second group of converter structures is used to convert the low order bits. This arrangement allows the provision of different types of current sources for the different converter structures depending upon the accuracy required for each current source. Control inputs are provided for acting upon the steering means to generate reference levels to which an input analog signal in an A/D converter is compared. By this technique, the D/A converters of the present invention may be utilized in A/D encoding and an improved conversion accuracy of about zero is provided.

Digital to analog converter having separate bit converters

A method and structure for correcting the voltage coefficient of resistance (VCR) of a resistor in a semiconductor body is described. The resistor may be diffused or ion implanted of one conductivity and formed in an isolated layer of the opposite type of conductivity. The layer is typically an epitaxial layer. A potential V.sub.1 is applied to one end of the resistor and a potential V.sub.2 being applied to the opposite end. The method provides means for controlling variations of the potential difference between the resistive region and the epitaxial layer, either to minimize them or to cause the distortions generated by such variations to be compensated for by equal distortions of opposite directions, such that the overall distortion will be equal to zero. There is provided means to cause the potential of the epitaxial layer to reach a suitable value, preferably a value that varies in the same manner as the average value of the resistor whose VCR is to be corrected.

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Cros de Cagnes, France

Francois X Delaporte