Sample Essay Inductors

Sample Essay Inductors Sample Essay: Inductors Introduction Inductors can be defined as a passive electronic component that is used for the purposes of energy storage. The inductance of the component is measured directly proportional to the number of turns in a coil and type of the material used in their making. This means that the conventional inductors were made of wire coils. Currently, technology have availed the CMOS based inductors, which are now commonly used in the high-speed electronic designs. CMOS spiral inductors have found a broad range of applications in high-speed analog signal processing, including impedance matching and gain boosting in wireless transceivers, bandwidth improvement in broadband data communications over the wire and optical channels, oscillators and modulators, radio frequency band pass filters, RF phase filters, RF power dividers and coupling of high frequency signals, to name but a few. Traditionally, passive inductors are off chip discrete components. The need for off chip communications with these passive c omponents severely limits the bandwidth, reduces the reliability, and increases the cost of systems. This resulted to efforts to fabricate inductors integrated on a single substrate monolithically. CMOS active inductors CMOS active inductors are active networks that consist mainly of MOS transistors. Resistors are sometimes used as feedback to improve the performance of the active inductors. Under certain dc biasing conditions and signal swing constraints, these networks exhibit inductive characteristics in a specific frequency range. As compared to with other types of inductors, such as the spiral inductors, CMOS active inductors offer the following advantages: low silicon consumption â€" because only MOS transistors are usually required in the realization of CMOS active inductors and inductance of these active inductors is proportional to transconductances of the transistors. Large and turn able self-resonant frequency CMOS active inductors with a large self-resonant frequency are highly desirable. Large and turn able quality factor the quality factor of CMOS active inductors is set by the ohmic loss of the inductors, arising mainly from the finite output resistance of the transconductors of the inductors. The quality factor of the CMOS active inductors can be increased by increasing the output resistance. Compatibility with digital CMOS technologies- CMOS active inductors can be realized using standard digital CMOS processes.  The applications of active inductors, however, are affected by several difficulties arising from the intrinsic characteristics of MOS devices. These difficulties include limited dynamic range, a high level of noise, and high sensitivity to process spread, supply voltage fluctuation, and ground bouncing. It should be noted that these limitations are not unique to CMOS active inductors, but rather common to all synthesized devices. They can also be reduced through innovative designs. Components of CMOS active inductor CMOS active inductors are manufactured through CMOS fabrication technology. For the fabrication process, a silicon wafer with CMOS power circuits is used as a substrate. An insulation layer already exists on the wafer, and via connections is exposed in order to have electric connection from power circuit to the inductor. The fabrication starts with a photoresist insulation layer. Via connections to CMOS circuitry re-patterned and then hard cured, to separate and insulate the inductor from the substrate. A thin metal film is deposited to serve as a seed layer for the lower magnetic core plate. A thick photoresist film is spun and patterned in order to formulate the molds for the lower magnetic core electroplating.