Ferranti Plc

Jeffrey Kane

A network of different weighted resistances, for example, binary resistances, coupled in parallel with each other, is provided in a semiconductor body by providing a plurality of substantially identical resistors, with different numbers of the identical resistors being coupled in parallel to provide the required different weighted resistances of the network, possibly, the constituent identical resistors of the different weighted resistances of the network being interdigitated with each other. The resistors, when comprising parts of current sources, each may be connected, individually, in series with a bipolar transistor, different identical bipolar transistors being connected in series with different resistors, so that there is associated with each of the different weighted resistances of the network, different total emitter areas, each product of a total emitter area and associated resistance being a constant, so that inversely corresponding, different weighted currents are obtained through the different weighted resistances, and a constant potential difference is applied across each constituent resistance of the network.

Semiconductor resistive network

A resistor comprises two identical resistor regions with each resistor region isolated within the semiconductor body by a P-N junction, and with one electrode-bearing end of each resistor region both connected together and to a common region surrounding the resistor regions within the semiconductor body, so that the common surrounding region is to be at the same potential level as the mid-point of the resistor considered as a whole.

Semiconductor device body having identical isolated composite resistor

In an integrated circuit semiconductor device different matched resistors are provided by at least one resistor comprising at least two matched resistor parts connected together, these resistor parts also being matched to each constituent resistor part of at least one different matched resistor of the device.

Semiconductor devices with matched resistor portions

A circuit arrangement at least partially embodied in a collector-diffusion-isolation (CDI) type device, in a semiconductor body comprising a thin layer initially wholly of one conductivity type on a substrate of the same conductivity type, has at least one component comprising a modification of previously known CDI type constructions i.e. with a combination of regions of the opposite conductivity type comprising a buried layer at the interface between the thin layer and the substrate, and an isolation barrier for the component extending through the thin layer to contact the buried layer, the modification comprising providing at least one outer annular region of the opposite conductivity type, adjacent to the surface of the thin layer remote from the substrate, and uniformly spaced from the combination of regions, there being a resistive component part between the outer annular region and the combination of regions, such that in the operation of the circuit arrangement, the device does not breakdown when a potential difference up to substantially twice the breakdown potential of the outer P-N junction of a component of any previously known CDI type consturction, and at least of 10 volts, is applied across the device, and/or controlled breakdown of the component of the device of the modified CDI type contruction takes place, but the breakdown current, flowing between regions of the device beyond the component and the combination of regions of the component, being reduced by the presence of the resistive part between the outer annular region and the combination of regions of the component.

Semiconductor devices and circuit arrangements including such devices

A circuit arrangement is at least partially embodied in a collector-diffusion-isolation (CDI) type device, in a semiconductor body comprising a thin layer initially wholly of one conductivity type on a substrate of the same conductivity type, and the device has a plurality of CDI-type components, each CDI-type component with a combination of regions of the opposite conductivity type, comprising a buried layer at the interface between the thin layer and the substrate, and an isolation barrier for the component extending through the thin layer to contact the buried layer, the circuit arrangement being such that no constituent component of the device breaks down when a potential difference of up to substantially twice the breakdown potential of the outer P-N junction of each CDI-type component, and at least of 10 volts, is applied across the device. Usually the substrate of the body is at the most negative potential level associated with the device. In one circuit arrangement the most positive potential level associated with the device is applied to the emitter (in the forward mode) of a CDI bipolar transistor arranged to operate in the inverse mode. Alternatively, the most positive potential level is applied to one end of a novel, high-voltage breakdown CDI-type component comprising a resistor structure, the resistive material comprising an inner surface region of the opposite conductivity type, within a region of said one conductivity type of the thin layer and defined by the combination of regions. In another circuit arrangement, the most positive potential level is applied to a novel, high-voltage breakdown CDI-type component comprising a contact structure having a contact on a layer of passivating material and overlaying an inner surface region of the component as referred to above. In yet another circuit arrangement, the most positive potential level is applied to a novel, high-voltage breakdown CDI-type component having only one contact, the contact being provided on an inner surface region of the component as referred to above.

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Cheadle Hulme, United Kingdom

Jeffrey Kane