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Design and Implementation of Low Power Delta Sigma Modulator for Audio Application

Yousefzadeh, Bahman | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42257 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Sharifkhani, Mohammad
  7. Abstract:
  8. iN This thesis, Design and implementation of a low voltage, low power Delta-Sigma Modulator (DSM) is presented. System level considerations have been discussed thoroughly. In addition a systematic design flow in the context of continuous time delta sigma modulators is provided. While voltage-domain signal processing becomes more difficult in deep sub-micron processes, a finer time resolution is achievable. Time-domain quantizers can ameliorate the design challenges of flash quantizers which arises from lower supply voltages and higher fraction of comparator metastable region. VCO based quantizer such as voltage to frequency and voltage to phase considered as time domain quantizers can be a good choice to achieve multi bit quantization. Furthermore voltage to frequency quantizer provides inherent dynamic element matching (DEM) and lower excess loop delay (ELD) which saves a great amount of power and chip area. Accordingly we proposed two low-voltage low-power DSMs, both implemented in TSMC 90nm CMOS, which consumes 123 W and 106 W from a 1V supply respectively. Simulation results using SPECTRE, and post processing using MATLAB shows SNDR of 78 and 75 dB for the modulators respectively. The fist DSM provides a systematic flow to the designers for future continuous time delta sigma modulators from audio to intermediate frequencies but the second one provides a very low power for the audio application. However the voltage to frequency quantizer known to improve the SNR characteristic and lessen the power consumption, but nonlinear VCO characteristic considered as a major bottleneck for quantizer design. In this thesis a simple technique which eliminates the even orders of harmonic distortion and Inter modulations from output quantizer spectrum is delivered. The technique can simply applied to all DSMs that use the voltage to frequency quantizers without any degradation to power, Area and inherent DEM property
  9. Keywords:
  10. Low Power System ; Delta-Sigma Modulator ; Continuous-Time Model ; Voltage to Frequency Quantizer ; Dynamic Element Matching

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