Abstract
Abstract 1894, Guglielmo Marconi began the research that lead to the development of the first practical wireless communication setups. Since then, wireless communication enormous influence on the cultural and social evolution of 20th century on everybody's daily life. What ever single directional wireless communication system such as broadcast system, TV, B.B. Call or bi-directional wireless communication system such as GSM system, PSCS, PHS, W-CDMA system, the way between human beings' communication grow up rapidly. Recently, our lab put a lot of efforts on silicon based CMOS RF front end such as low noise amplifier (LNA), microwave mixer, voltage controlled oscillator (VCO), and pre-amplifier & post-amplifier of high speed optical fiber communication system. Many parts, especially microwave inductors, of these integrated circuits need to connect to off -chip discrete devices. Such process will result in unwanted bounding wire inductance and coupling capacitor effects that worsen performance of the circuit. If we can make high-Q on-chip microwave inductors, we can enormously reduce the size and costs of wireless communication setups. Most parts of RF front end were made of GaAs technology because its semi-insulating (lossless) substrate. Comparing with semi-insulating GaAs substrate, silicon substrate has much higher conductance that induce serious power loss. An on-chip microwave inductor will also induce eddy current on lossy substrate and may loss its energy through substrate to the ground. Coupling effects between active devices and substrate also induce coupling current that make device performance get worse in such case. These effects result from silicon based on-chip microwave inductors and devices reduce the whole system performance. However, there is a good solution. Since we know that porous silicon layer (PSL) has much higher resistivity comparing with conventional silicon substrate, we can apply PSL into substrate engineering and can take advantage of high resistivity of PSL to improve circuit performance such as quality factor…etc.