The paper deals with laser trimming of film resistors. The finite-difference solution of the electric field calculated by a digital computer gives the total resistance and the inhomogeneous current distribution within the resistor area. The current noise voltage was found to be proportional to the sum of reciprocal subareas wherein the current density is approximately constant. Resistor trimming is modelled by finite increments of cut length to obtain the resistance trim rate and the trim sensitivity.Known and new resistor geometries and cut configurations are compared (based on the same resistor area and the same initial tolerance of ± 20%) to find the optimal geometry depending on the ratio of the nominal resistance value to the sheet resistivity. Diagrams are given leading to practical design rules not only for resistance trimming but also for deterministic and functional tuning.

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Übersicht:Zur monolithischen Integration schmalbandiger Filter in MOS-Technologie wurden neue rekursive CCD-Grundbausteine -die CCD-Resonatoren -entwickelt. Während die Mittenfrequenz dieser Resonatoren bei eingeprägter Taktfrequenz durch die Anzahl von Verzögerungselementen bestimmt wird, hängt die Bandbreite vom Verhältnis zweier Kapazitäten ab. Da CCDs sehr gute Übertragungseigenschaften aufweisen, arbeiten die Resonatoren bei Signalfrequenzen bis zu einigen hundert kHz mit Mittenfrequenzabweichungen von etwa 10" 4 im Temperaturbereich 40 K. Über die Ableitung der wichtigsten Eigenschaften eines einfachen Resonators und von allgemeineren Formen sowie über Entwurfsregeln und Meßergebnisse wird berichtet.Abstract: This paper presents new recursive CCD building blocks -the CCD resonators -which are very useful to implement filters with narrow bandwidths in MOS technology. The center frequency of the CCD resonators is determined by the clock frequency and the number of delay elements in the loop. But the g-factor is given by a capacitance ratio. Because of the good transfer characteristic of CCDs the resonators work very well with a center frequency deviation of about 10~4 within the temperature range 40 K up to signal frequencies of some hundred kHz. The deriviation of characteristic data of the basic resonator and generalized resonators as well as design considerations and experimental results are presented.Für die Dokumentation: Monolithisch integriertes Filter / analoges Filter / CCD / rekursives Filter / Bandpaß / Resonator /

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