System-on-Chip for Portable Audio - SOCPOD

Today's multimedia applications use a huge variety of high performance integrated components (off-the-shelf components and digital processors). They realize digital processing functions like encoding or decoding of video or audio streams (processor cores and software), digital interfaces (USB, 2-wire, flash memory, etc.), analog interfaces (analog-to-digital converters – ADCs and digital-to-analog converters – DACs for video as well as audio signals) and power management functions (handling a variety of supply voltages). While highest quality in video and audio performance was the main design criteria for long time, a new generation of multimedia products evolved over the recent years. The availability of video and audio virtually everywhere, independent from mains supply, has become a major trend and a huge market for suppliers. Now, portable multimedia products have dramatically changed the metrics of the required components. Space and battery life time have become of major concern to the designers, eventually even compromising the performance.

These design issues can only be solved by increasing the integration level, combining most, if not all, multimedia functions on a single integrated circuit (System-on-Chip SoC, System-in-Package SiP). Most advanced fabrication technology is required and the challenge of the designers is not only found in the tremendous design complexity, but also in the integration of critical analog and mixed-signal functions, as described above.

Project socPod addresses these problems for portable audio products and research in new analog interfaces, especially oversampled audio ADCs and DACs. Oversampled data-converters, well suited for SoC integration, are adapted to advanced fabrication technologies as well as reduced supply voltages and lowest power consumption, while still delivering a target performance of 93-95 dB SNR. This is done by a global optimization at system, architecture and circuit level of the signal path from anti-aliasing filter via noise shaper, decimation and interpolation filters to equalizer and smoothing filter.

socPod is a Cooperation between

• Institute of Electronics (Graz University of Technology),
• School of Systems Engineering (Carinthia University of Applied Sciences),
• austriamicrosystems AG (industrial partner)

Project Duration
1.9.2006 - 30.9.2009

Contribution of Carinthia University of Applied Sciences
Carinthia University of Applied Sciences designed and implemented selected structures for digital signal processing functions. Special architectures and circuits for low power decimation and interpolation filters, parametric equalizers and arithmetic units for software programmable DSP cores were developed and, where required, also fabricated on a testchip. Compared to conventional structures, the power consumption could be reduced up to 75%.

Mask Layout of CIC Filter Unit

Publications

• Yingwei Wang, Chi Zhang, Erwin Ofner, Lucas Groposo: "Third Order Delta Sigma Modulator for Portable Audio", in Proceedings of Austrochip 2010, Oct. 2010, Villach, pp79-82, ISBN 978-3-200-01945-4.
• Erwin Ofner, Chi Zhang, Haifeng Zhou: "Integration of Low-Power Decimation Filters", 3. Forschungsforum der österreichischen Fachhochschulen, April 2009, Villach, pp147-151, ISBN 978-3-853912850.
• Haifeng Zhou, Chi Zhang, Erwin Ofner: "Low-Power Decimation Filter for Portable Audio Applications", in Proceedings of Austrochip 2008 in Linz, Oct 2008, pp48-51, ISBN 987-3-200-01330-8.
• Stephen T. Burgess, Erwin Ofner: "Recursive All-Pass Interpolation Filters for Digital Audio Applications", in Proceedings of Austrochip 2008 in Linz, Oct 2008, pp52-55, ISBN 987-3-200-01330-8.

Master Theses

• Shanmukha Reddy Mandha: CORDIC Based Equalizer Coefficients Calculation Unit
• Stephen Burgess: Recursive All-Pass Filters for Efficient Interpolation of Discrete Time Audio Signals
• Haifeng Zhou: The Low Power Design and the VLSI Implementation of a Decimation Filter for an Over-sampled Data Converter

Funding

The project was funded by the FIT-IT program of the Austrian Research Promotion Agency (FFG) and the industrial partner.

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