The present invention relates generally to the field of data communication. More particularity, the present invention discloses a structure and a corresponding method of implementing an inductive component of accurate inductance value for optical communication circuits operating with an input clock speed of a few to 100 GHz/Sec where an accurate inductance value is often required to achieve a correspondingly accurate operating frequency. Thus, the present invention can be included into many circuits for the implementation of subsystem functions such as counters, timers, frequency multipliers and Phase Locked Loop (PLL) in an optical switch IC (Integrated Circuit) for optical communication. Additional related applications are: Optical communication at 2.48 Gbit/sec (OC48) and 40 Gbit/sec (OC768) data rate, Gigabit Ethernet, 10 Gigabit Ethernet, Blue Tooth technology (2.4 GHz) and wireless LAN (5.2 GHz). At such a high data rate, the hardware infrastructure for a multimedia information super highway is also enabled.
Optical Fiber has been used in voice and data communication for some time now due to its high bandwidth and excellent signal quality resulting from its immunity to electromagnetic interference. The inherent optical data rate from a modulated single-mode laser beam travelling through an optical fiber is expected to well exceed 1000 Gbit/sec.
To keep up with the data rate of optical data communications, the associated signal processing IC (Integrated Circuit) need to operate in the multiple GHz (Gegahertz, 1 Gegahertz=109 cycles/sec) to hundreds of GHz range of clock frequency. To improve the performance parameters of such high speed circuits, the inclusion of inductive components properly designed for RF (Radio Frequency) operation, another type of stored-energy device in addition to the capacitive component, has become increasingly popular. For example, Yue et al described one type of on-chip spiral inductor with patterned ground shields for Si-Based RF IC""s operating in a frequency range of 1-2 GHz. Here, a single ground plane was employed between a spiral inductor and Silicon substrate to increase the inductor Q (quality factor). Furthermore, the ground plane was patterned in a multiple-finger like structure with slots orthogonal to the inductor spiral to minimize an induced eddy current herein thus associated RF power loss (On-Chip Spiral Inductors with Patterned Ground Shields for Si-Based RF IC""s, C. Patrick Yue et al, IEEE Journal of Solid-State Circuits, Vol. 33, NO. 5, May 1998). For another example, Zhou et al described monolithic transformers and their application in a differential CMOS RF low-noise amplifier where each of the monolithic transformers was implemented as a set of two coplanar, interwound spirals (Monolithic Transformers and Their Application in a Differential CMOS RF Low-Noise Amplifier, Jianjun J. Zhou et al, IEEE Journal of Solid-State Circuits, Vol. 33, NO. 12, December 1998). In U.S. Pat. No. 6,188,295 B1 dated Feb. 13, 2001, Tsai disclosed a multi-layered circuit with a top circuit interconnection layer and a lower patterned inductor layer sandwiched between two ground layers both located below the top circuit interconnection layer. By cutting through or partially notching certain micro-strips of the top circuit interconnection layer either the associated equivalent circuit capacitance is adjusted accordingly or a serially coupled inductance-capacitance circuit is formed. Regardless of these references, however, where a precise inductance value is required of the monolithic inductor for an application, for example an oscillator circuit having a precisely specified output frequency that is controlled by the monolithic inductor, there is a need of a simple systematic method whereby the monolithic inductor can be quickly implemented with low cost of development.
The present invention is directed to a new design and method of implementing an inductive component within a high frequency integrated circuit having a structure of multiple conductive layers.
The first objective of this invention is for the inductive component to achieve an accurate, pre-determined inductance value.
A second objective of this invention is for the method of implementation of the inductive component to be simple, systematic, quick and low cost.
A third objective of this invention is for the method of implementation of the inductive component to be extendable to the implementation of a precision transformer component.
Other objectives, together with the foregoing are attained in the exercise of the invention in the following description and resulting in the embodiment illustrated in the accompanying drawings.