Fritz Rothacher's Home Page on Sample-Rate Conversion and More

Address: Fritz Rothacher, Bahnhofstr. 7, D-86150 Augsburg, Germany
Email:   f.rothacher@ieee.org

Jan 98 -       : Research and Development Wireless ASICs
                 Infineon Technologies, Balanstr. 73, 81541 Munich, Germany
                 (former Siemens Semiconductor)

Jun 95 - Oct 97: Rockwell Semiconductor Systems, Newport Beach CA, USA
                 (now Conexant)

Oct 90 - Feb 95: Integrated Systems Laboratory, ETH Zuerich, Switzerland

• Fritz M. Rothacher, ``Sample-Rate Conversion: Algorithms and VLSI Implementation (PDF-format)'', PhD thesis, Integrated Systems Lab, Swiss Federal Institute of Technology (ETH Zürich), 1995, ISBN 3-89191-873-9
  
  Many modern signal processing tasks are performed in the digital domain. Various sample rates are used depending on the required signal quality and the available bandwidth. Sample-rate conversion is therefore inevitable to interface systems with different sample rates. In this thesis the concept of digital sample-rate conversion by integer ratios is extended to arbitrary ratios and the trade-offs of various design parameters for audio applications are discussed.
  Conceptually, the source samples are interpolated to a heavily oversampled intermediate signal using a high-order digital filter. To allow a conversion between arbitrary sample rates this intermediate signal is transformed into a pseudo-analog representation by holding the value in-between the interpolated samples. The resulting continuous-time signal is then resampled at the sink sample rate.
  For an infinite interpolation factor, ideal filters, and jitter-free sampling clocks digital sample-rate conversion is lossless. In this thesis the error contributions of the various non-idealities are quantified. The synthesis of high-order (>20000) narrow-band lowpass filters and their quantization properties are discussed. A digital PLL is presented, which allows to measure precisely the sink sampling moment relative to the source samples, while attenuating jitter of the sampling clocks. The effects of the non-uniform sampling due to clock jitter are treated.
  An ASIC for fully digital sample-rate conversion has been developed, fabricated, and characterized using an all-digital measurement system. A new (complex) window technique for the FFT is introduced, which minimizes the window side effects when doing spectrum analysis of multirate discrete-time signals. Based on the results of this thesis, the design parameters for a converter with full 20-bit quality are proposed.
  
  The full postscript version is 8754K (2173K compressed): Sample-Rate Conversion: ... (Postscript).
  The version without figures is 451K (145K compressed): Sample-Rate Conversion: ... (Postscript, no figures).

• F. Rothacher and N. Felber, VLSI Implementation of a Fully Digital Asynchronous Audio Sample-Rate Converter, Proceedings of the 96th Convention of the AES, Amsterdam, 1994
  
  
• F. Rothacher, N. Felber, and H. Kaeslin, High-Speed VLSI Workpiece Position Measurement using Normalized 2D-Correlation, Proceedings of the SPIE Conference on Electronic Imaging, San Jose, 1994
  
  For workpiece recognition, the image processing unit of an assembly robot must be fast and reliable. To improve an already existing system, we implemented an ASIC for real-time image correlation from a standard video image based on an investigation of several algorithms for 2D greyscale image correlation. The architecture contains four parallel multipliers and uses a three-level pipelining schema. The ASIC which is realized in a standard and macrocell technique achieves a sustained performance of 160'000'000 MAC/s. A speed-up factor of 12 compared to a DSP56116 implementation at the same clock speed is obtained.
  
  
• F. Rothacher, N. Felber, and H. Kaeslin, ASIC for 2-Dimensional Normalized Greyscale Image Correlation in Realtime, in Proceedings European Conf. on Design Automation, Paris, 1993
  
  
• F. Rothacher and N. Felber, VLSI Implementation of a Fully Digital Asynchronous Audio Sample-Rate Converter, Technical Report No. 93/27, Integrated Systems Lab, ETH Zurich, December 1993
  
  
• F. Rothacher, ASIC for 2-Dimensional Normalized Greyscale Image Correlation in Realtime, Design and Test Report, Technical Report No. 92/04, Integrated Systems Lab, ETH Zurich, October 1992
  
  
• F. Rothacher, Comparison of Correlation Algorithms for the ESEC Wirebonder, Technical Report No. 91/04, Integrated Systems Lab, ETH Zurich, March 1991
  
  
• F. Rothacher and A.Wieland, DIDI: Audio sampling-frequency converter for arbitrary changing ratios, Master's thesis, Integrated Systems Lab, ETH Zurich, February 1990

• Contact Norbert Felber, Integrated Systems Lab, ETH Zurich