1 / 3

A 94dB SFDR 78dB DR 2.2MHz BW Multi-bit Delta-Sigma Modulator with Noise Shaping DAC

A 94dB SFDR 78dB DR 2.2MHz BW Multi-bit Delta-Sigma Modulator with Noise Shaping DAC. Application: For high SNR and SFDR, such as xDSL and Hi-Fi audio. Preferred architecture : Multi-bit ∆Σ M (Delta-Sigma Modulator). Problem : Nonlinear DAC in the feedback loop degrades the performance.

evita
Télécharger la présentation

A 94dB SFDR 78dB DR 2.2MHz BW Multi-bit Delta-Sigma Modulator with Noise Shaping DAC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A 94dB SFDR 78dB DR 2.2MHz BW Multi-bit Delta-Sigma Modulator with Noise Shaping DAC Application: For high SNR and SFDR, such as xDSL and Hi-Fi audio.Preferred architecture: Multi-bit ∆ΣM (Delta-Sigma Modulator).Problem: Nonlinear DAC in the feedback loop degrades the performance. Nonlinear DAC Existing solution • Pros: DEM randomizes the mismatch in DAC and spread the energy of the toned noise to the entire band. Thus, the nonlinearity is improved and the SFDR is increased. • Cons: The spread noise increases the noise floor, and hence the in-band noise power. SNR of the DSM is degraded. • In conclusion: The DEM improves SFDR, but degrades SNR. In other words, it trades SNR for SFDR.

  2. Proposed Lowpass DSM with Noise Shaping DAC Quantiazation Noise Q(z) • 1st -order shaping to DAC noise • DEM reduces tones • Noise shaping DAC or NSDEM improves both SFDR and SNR U(z) Quantizer V(z) H(z) DAC with NSDEM HI(z) HD(z) DEM 5th-order 4-bit Quan. lowpass DSM with NSDEM DAC Noise D(z) Accumulator Differentiator H(z) – loop filter Quantizer HI(z) DAC + HD(z) DEM (PDWA)

  3. No input signal • DAC thermal noise is shaped • Reference noise is also shaped 94dB NSDEM is off NSDEM is on Noise floor is limited by switches thermal noise of input signal path • Unlike most of the existing DEMs that trade SNR for SFDR. • NSDEM improves both DAC SFDR and SNR. • NSDEM shapes the inherent DAC thermal noise. • Fabricated DSM chip meets the specification for ADSL2+.

More Related