| 摘要 |
In certain circuits, it is desirable to match the electrical characteristics, (e.g., thresholds), of two (or more) MOS transistors. For example, in an ECL output buffer, a first transistor is a voltage reference, and a second transistor is an output buffer controlled by this voltage reference. However, the orientation of the transistors may affect their electrical characteristics. This may be due to the source/drain ion implantation step that occurs at an angle off the vertical, or other processing effects. The present invention provides symmetrical MOS transistors having characteristics that are independent of orientation. For example, a square gate layout provides both vertical and horizontal current components, thereby obtaining 90 degree rotational symmetry.
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