Integrated RF components in a SiGe bipolar technology

Several components for the design of monolithic RF transceivers on silicon substrates are presented and discussed. They are integrated in a manufacturable analog SiGe bipolar technology without any significant process alterations. Spiral inductors have inductance values in the range of ∼0.15-80 nH with typical maximum quality-factors (Q max) of 3-20. The Q max's are highest if the doping concentration under the inductors is kept minimum. It is shown that the inductor area is an important parameter toward optimization of Q max at a given frequency. The inductors can be represented in circuit design by a simple lumped-element model. MOS capacitors have Q's of ∼20/f (GHz)/C(pF), metal-insulator-metal (MIM) capacitors reach Q's of ∼80/f(GHz) /C(pF), and varactors with a 40% tuning range have Q's of ∼70/f(GHz)/C(pF). Those devices can be modeled by using lumped elements as well. The accuracy of the modeling is verified by comparing the simulated and the measured high-frequency characteristics of a fully integrated, passive-element bandpass filter.