Rigorous investigations of a SiGe:C BiCMOS ring oscillator with optimized gate delay

This paper presents a SiGe HBT ring oscillator (RO) achieving a minimum gate delay τ_gate of 2.7 ps in order to benchmark the applicability of a BiCMOS technology for millimeter wave and sub-millimeter wave applications. State-of-the-art circuit performance is achieved through optimized transistor layout parameters. The transistor model is verified through DC and RF measurements (up to 110GHz). Note that, the RO as well as the transistor measurements were performed on the same wafer. Excellent agreement between measurements and compact model simulation is shown. A simple approach is presented that approximates the temperature rise in the local circuit area resulting from mutual heating of all active and passive components. RO simulations were carried out using the local circuit temperature in dependence of the dissipated power.