Physical constraints in design of a lowest-phase noise SiGe VCO

Low phase noise oscillators are critical to signal recognition and separation in poor reception conditions. Typically the choice is between a large, high performance hybrid oscillator or a lower performance integrated solution. It is possible to use integrated circuit components to construct a high performance oscillator, but only with great attention to detail. Every IC component has to be optimized in parallel to balance the constraints of spiral inductors, metal-insulator-metal (MIM) capacitors, somewhat lossy varactors, and active devices with breakdown limitations. Physical implementation is critical; some locations are insensitive to trace resistance, other areas are sensitive to even tiedown placement. This paper is intended to discuss, and demonstrate the last mile of integrated circuit VCO design for robust systems, which is less discussed, but maybe just as important as innovative circuit approaches.