Dissipation, Thermals, and Rds(on)

This article explores the significance of the Rds(on) specification of a MOSFET in a linear voltage amplifier and implications on Thermal Design - dissipation, thermal resistances, and heatsinking. It may be of interest to put this in perspective and highlight the connection between these subjects.

A personal account of a professional journey that led to the creation of Neurochrome, a company successfully serving audio enthusiasts all over the world with a complete range of power amplifiers kits and circuits, all well-engineered, thoroughly tested, and well-documented. Neurochrome is a small, highly dedicated audio company, providing inspiration, or perhaps a forewarning, for those wishing to venture into the audio business.

As the demand for safe and efficient power solutions for equipment grows, Schurter is committed to addressing the impact of power loss as it relates to Power Entry Modules (PEMs). To emphasize the necessity of carefully addressing power dissipation and temperature deratings for all PEM related components to ensure long-term safe operation, the Swiss technology specialist released a useful new white paper.

Anticipating the early 2024 tradeshows, Lavoce Italiana announced the DN20.300T, a larger version of the flagship 1.4" throat compression driver with 3" voice coil, the existing DN14.300T. The new DN20.300T uses a uniquely optimized throat adaptor which has been carefully engineered to expand the exit to 2" with no degradation of performance. The new compression driver also offers improved thermal dissipation from motor to horn by increasing the adaptor surface area in direct contact with the driver motor.

Magnachip Semiconductor Corporation announced has begun mass production of two new 650V Super Junction Metal-Oxide-Semiconductor Field-Effect Transistors (SJ MOSFET) devices. These new SJ MOSFETs offer excellent design flexibility, efficient heat dissipation, and low RDS(on) (the resistance value between the drain and the source of MOSFETs during on-state operation) characteristics. As a result, they are well-suited for various applications that require compact size and high efficiency inc consumer electronics, as well as for chargers and adapters.

The brand new generation of Beyma compression drivers originates from an intense R&D effort and two patent-pending innovations. Unveiled at ISE 2013, Beyma's four base designs with 2 throat sizes, 4 voice coil diameters, 3 diaphragm materials and 2 magnet types, allow for a total of 12 new models (for now). Scheduled to be launched progressively during 2023, these new Beyma state-of-the-art high frequency transducers deliver new exciting possibilities for speaker designs.

Hypex Electronics announced a new and improved iteration of its popular NCORE Class-D amplifier technology and unveiled the NCx500 OEM, the first of a new NCOREx family of modules to be launched. According to the Dutch company, the new technology will afford at least 2x better performance compared to original NCORE products. Hypex will introduce the new NCOREx technology at the ISE and High End shows in May 2022, paving the way for future OEM products.

For those readers following the fascinating article series by Morty Tarr on "Cascodes, Folded Cascodes, and Current Mirrors," this final article in the series contains an additional section with important aspects of amplifier design. In the first two parts of this article series, Tarr discussed the technical merits of cascodes and related circuits. This useful addendum covers a simple test circuit for matching FET devices, the fascinating story of the Blowtorch Line Stage design, and additional notes on inverting and non-inverting amplifier stages and integrators. This article was originally published in audioXpress, December 2021.

Prolight+Sound 2019 was a reassuring show for all companies working with Eighteen Sound drivers. The company is now, together with Ciare, part of the B&C Speakers SpA Group of companies. At the Frankfurt show, Eighteen Sound and Ciare had their own separate booth (side by side with B&C), showing lots of new products in all areas of the portfolio. Of course, Eighteen Sound is renowned for its low frequency drivers, and during Prolight+Sound the company impressed with the new 18NTLW500 next generation high performance subwoofer using Tetracoil technology.