Integrated circuit on chip trimming
AssigneeNational Semiconductor Corporation
InventorRobert C. Dobkin
Life of this patent
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Abstract
In a monolithic integrated circuit, on-chip trimming is implemented by connecting a zener diode across each element of a plural element trimmable resistor. Adjacent diodes are connected back to back and a pair of conventional bonding pads connected thereto. In trimming, when it is desired to short out one of the trimmable elements, the associated diode is subjected to an overload pulse by means of test probes applied to the bonding pads. Since the diodes are connected back to back, the pulse polarity will determine which diode is overloaded in the reverse bias condition. Thus, the trimmable element to be shorted is determined by pulse polarity and only one bonding pad is needed for each pair of trimmable elements.
Claims8
In integrated circuit trimming, wherein a series of passive circuit elements are provided with a shunting zener diode and a series of circuit pads are connected to said diodes whereby each zener diode can selectively be coupled to a source of reverse potential that is greater than the reverse breakdown of said diode and said source is capable of supplying sufficient current to cause said diode to short itself permanently thereby to bypass said element, the improvement comprising:
- means for connecting adjacent zener diodes in said series in back-to-back relationship;
- and
- means for making pad connections only to adjacent pairs of back-to-back zener diodes whereby the diode in said pair is subjected to a reverse polarity pulse when said diode is to be shorted and the pulse polarity can be reversed when the other diode in said pair is to be shorted, and whereby a reduced bonding pad count is achieved.
A silicon monolithic integrated circuit including active and passive components in a combination that can be trimmed in wafer form using a trimmable section, said trimmable section comprising:
- a plurality of series connected passive elements, selected ones of which are to be shorted;
- a plurality of zener diodes arrayed in back-to-back connected pairs and said diodes being connected to said passive elements to permit the association of a zener diode with each passive element in said plurality that is to be shorted to achieve trimming;
- and
- means coupled to each of said back-to-back connected pairs to permit the application of electrical energy to any one of said pairs whereby a single diode in said one of said pairs can be selectively shorted.
Dependencies are inferred from the claim text.