Fairchild Semiconductor Corporation

Jerry Gray

Susan M Keown

Geoff Hannington

Dana J Fraser

Ray A Mentzer

Gaetan L Mathieu

Circuit configurations are described for use with split lead leadframes and relatively isolated quiet and noisy power rails to reduce power rail noise and circuit noise. An octal register transceiver circuit incorporates a latch (300) coupled to relatively quiet power rails (42,44) and an output buffer circuit (400) having an input circuit coupled to the latch (300) and relatively quiet power rails (42,44). The output driver transistors (Q433,Q434) of the output buffer circuit (400) are coupled to the relatively noisy output power rails (52,54) to isolate the latch circuit from power rail noise and minimize erroneous operation of the latch. A DC Miller Killer circuit (450) is constructed with delay control components (D456,D457,R460) and an alternative discharge path (R458,D459) to reduce aggravation of power rail noise during operation of DCMK.

Transceiver with isolated power rails for ground bounce reduction

To reduce the effect of on-chip power rail perturbation on integrated circuit performance, a lead configuration is provided having two or more leads originating at a single terminal, e.g. a pin. While merged near the pin in a common segment, the leads connect on the integrated circuit chip to respective isolated internal rails of the same type serving respective device stages. Preferably, the inductance of the common segment is minimized. In accordance with the invention, an octal registered transceiver is provided with isolated V.sub.cc and ground rails for the latch and output buffers. The lead configuration described above is used for both V.sub.cc and ground. Several circuits are improved to optimize performance of the device, including a DC Miller killer circuit. Also in accordance with the invention, the paddle of a PDIP leadframe is supported by tiebars that extends to the dambars at the sides of the leadframe. An additional lead is obtained from a conductive element originating near the paddle and supported by one of the two lead frame rails.

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Cape Elizabeth, ME, United States of America

Jerry Gray