For many years, a majority of class D audio amplifiers have been switching at a relatively low frequency (several hundreds of kHz). However, there are several drawbacks associated with relatively low switching frequency: 1: Limited loop gain that could bottleneck the linearity of the class D amplifier, especially those delivering high output power. 2: Relatively expensive and bulky LC filters, which are often required to meet the stringent EMI standard for applications such as automotive applications. 3: Tricky frequency compensation when the LC filter is incorporated in the amplifiers’ feedback loop. Class D amplifiers switching with relatively high frequency (>2 MHz) can naturally mitigate these issues. In this talk, we will review some of the most recent development in high-switching-frequency class D audio amplifiers. Techniques to mitigate EMI, reduce idle power, compensate LC filter non-linearity, and improve the key performance such as dynamic range, THD+N and PSRR will be discussed.
Dr. Qinwen Fan received the B.Sc. degree in electronic science and technology from Nankai University in China in 2006 and the M.Sc. degree (cum laude) in microelectronics from Delft University of Technology, The Netherlands in 2008. She further continued as a Ph.D. candidate in the same university and has received the degree in 2013. From October 2012 to May 2015, she worked at Maxim Integrated Products in Delft, The Netherlands. From June 2015 to January 2017, she worked at Mellanox in Delft, the Netherlands. Since 2017, she rejoined the Delft University of Technology and is currently an Assistant Professor in the electronics and instrumentation laboratory.
Her current research interests include precision analog; class D audio amplifiers; DC-DC converters for energy harvesters; current-sensing amplifiers.
Dr. Fan serves as an associate editor of Open Journal of the Solid-State Circuits Society (OJ-SSCS), a TPC member of the International Solid-State Circuits Conference (ISSCC), VLSI Symposium on Technology and Circuits, and European Solid-state circuits conference (ESSCIRC).