ECE 445S Real-Time Digital Signal Processing Laboratory - Lecture 10

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Lecture

• Example tradeoffs in sampling rate and amplitude resolution for analog-to-digital converters a.k.a. digitizers:

  Analog-to-Digital Converter	Channels	Bits/sample	Sampling rate	Signal Bandwidth
  NI PXIe-5186	2	8	12.5 GSPS	5 GHz
  NI PXI-5154	2	8	2 GSPS	1 GHz
  NI PXIe-5122	1	14	100 MSPS
  NI PXI-5192	1	16	15 MSPS
  NI PXI-5192	1	24	500 KSPS

• Lecture slides on Data Conversion in PowerPoint format.

• Course Reader Appendix J Handout: Noise-Shaped Feedback Coding.

• Traditional Model for power consumption in data converters is C V_dd² f_s 2^B, where
  • C is capacitance
  • V_dd is the supply voltage
  • f_s is the sampling rate (a.k.a. conversion rate)
  • B is the number of bits.
  Formula holds for low-resolution data converters operating at fs < 10 MHz.

• For state-of-the-art data converters, power consumption would be
  • proportional to f_s² instead of f_s for f_s > 100 MHz
  • proportional to 4^B instead of 2^B for high-resolution data converters (SNDR > 50 dB)
  Reference: 10-minute video presentation by Prof. Boris Murmann (Stanford University).

• Lecture on Data Conversion in spring 2014 on Videos for Part 1 and Part 2 of the lecture.

Supplemental Material

• Understanding PDM Digital Audio, Dr. Thomas D. Kite, Audio Precision. "PDM stands for pulse density modulation. However, it is really better summarized as 'oversampled 1-bit audio', as it is nothing more than a high sampling rate, single-bit digital system." This application note describes the signal processing involved in creating the output signal for a digital microphone.

• Bruce Wooley, "Cascaded Noise-Shaping Modulators for Oversampled Data Conversion", February 3, 2004, seminar given at UT Austin. Slide 10 quantifies the Dynamic Range vs. Oversampling Ratio for first-, second-, and third-order sigma-delta modulators.

Last updated 01/02/23. Send comments to bevans@ece.utexas.edu