We all know that doctors make the worst patients because they always laughingly tell us so. But how do we rate at taking our own medicine?

view from the chair: I go to a friend

This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

The large-scale harvesting of solar energy is an important action to decelerate the observed climate changes. Reliably operating solar-energy systems composing of solar arrays and their interfacing converters are of prime importance to maximize solar-energy harvesting. The paper investigates the solar-generator interfacing in terms of current-fed (CF) maximum-power-point (MPP) tracking converter. The investigations show that the CF converter under input-voltage control can usually operate from the short-circuit to open-circuit conditions of the solar generator without stability problems. When the output voltage or current has to be controlled constant, the converter may become unstable at the MPP due to the negative incremental resistance appearing at its input terminals. In practice, this means that the operating range of the CF converter has to be limited to the voltages less than the MPP voltage, when the output-voltage or current control is active. Practical evidence is provided based on a CF superbuck converter derived from the corresponding voltage-fed converter applying duality-transformation methods and supplied by an actual solar panel.

Issues on Solar-Generator Interfacing With Current-Fed MPP-Tracking Converters

Microbial fuel cells (MFC) are alternative renewable power sources that can directly produce electricity from biodegradable substances. However, due to their low power and voltage production, power management systems (PMS) are required to process the MFC power to a more readily usable level. For this application, a monolithic PMS with an integrated maximum power extraction algorithm (MPEA) is proposed. The MPEA allows for quick and accurate pin-pointing of the matching conditions for maximum power transfer from the MFC to the PMS. The PMS delivers a regulated fixed voltage from low fluctuating voltages produced by MFC at maximum power point to a supercapacitor from which electronic devices, such as wireless sensors, for extended operation time can be directly powered. Along with the MPEA system, the PMS is composed of a dc-dc boost converter operating in discontinuous conduction mode to maximize efficiency. In addition, a zero current switching tracking loop is proposed to improve overall system efficiency and minimize losses in the PMS through accurate P-type Metal-oxide-semiconductor field-effect transistor on/off timing control. The PMS circuit was fabricated in 0.5-μm CMOS technology. The maximum dynamic efficiency measured was ~58% for a load of ~250 μW.

Power Management System With Integrated Maximum Power Extraction Algorithm for Microbial Fuel Cells

State-of-the-art literature review of WPT: Current limitations and solutions on IPT

The limited usefulness of the maximum power transfer theorem in practice is argued. Inappropriately, the utility and value of the maximum power transfer theorem are often elevated to be religious icons of electrical engineering. While the theorem appears to be useful, often in real circuits the load impedance is not set equal to the complex conjugate of the equivalent impedance of the connecting source. When the load impedance happens to be equal to the complex conjugate of the source impedance, other practical reasons for this type of impedance matching exists, other than effecting maximum power transfer. Some reasons are discussed in a straightforward fashion.

K.L. Kaiser

Papers

“Deglorifying” the Maximum Power Transfer Theorem and Factors in Impedance Selection