Patents Represented by Attorney T. R. Berthold
  • Patent number: 4513254
    Abstract: An adjustable filter arrangement is disclosed which is implemented in integrated circuit technologies. The filter configuration corresponds to a SALLEN-KEY filter in which the amplifier function is obtained by a transistor device, the R1 and R2 resistor functions are obtained by a first pair of suitably connected diodes, and the C1 and C2 functions are also integrated into the semiconductor chip. Adjustment of the natural frequency of the filter is obtained by the value of an externally supplied control current through the pair of diodes corresponding to R1 and R2. Adjustment of the damping characteristic of the filter is obtained by supplying a second control current to cause a relative change between the values of R1 and R2. No external components need be attached to the integrated circuit filter.
    Type: Grant
    Filed: May 16, 1983
    Date of Patent: April 23, 1985
    Assignee: International Business Machines Corporation
    Inventor: Jerome D. Harr