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2 answers
88 views

DSM Model Not Producing Expected Noise Shaping

I am trying to design a 2nd Order CIFB DSM ADC on Simulink based off the values I have extracted from Richard Schreier's Delta Sigma Modulation Toolbox. However, when I ran the model according to the ...
2 votes
3 answers
171 views

Optimized Filters for Delta-Sigma Converters with Finite Time Limit

Quick read of my question The optimum estimator of the mean for N samples of a sampled DC level in the presence of white noise is a block average (an average with all samples given equal weight). What ...
0 votes
0 answers
35 views

Driving bandpass DSM with tone close to full-scale - stability issue?

I am experimenting with Dr. Schreier's DSM toolbox for MATLAB. I stumbled over a strange phenomenon when having a look at a bandpass DSM in demo-script 2. If I increased the amplitude of the test-tone ...
0 votes
1 answer
330 views

How to implement a filter for a sigma delta modulator?

I am working on a project involving an accelerometer that outputs a pdm signal, which needs to be decoded to an acceleration. The device itself outputs a clock and data line, we just have to sample ...
0 votes
2 answers
1k views

sigma delta modulator for DAC

Can someone please provide an overview of sigma delta DAC? In particular, I would like to know how does the sigma delta modulator, which is digital, works for DAC. What is difference between sigma ...
1 vote
1 answer
235 views

Delta sigma modulator harmonics appearing with a sine wave input

I am simulating a first order delta sigma modulator (DSM) used as an ADC. The input to my DSM is a full scale sine wave. The power spectral density I expect from the DSM output is as follows : The ...
1 vote
1 answer
173 views

Dynamic Range Scaling for Delta Sigma Modulation

I've been trying to follow along with this example in the book "Understanding Delta Sigma Data Converters" and I am completely confused as to how the authors came about the appropriate ...
0 votes
1 answer
105 views

Smart MEMS microphones

Edit: from Wikipedia's Delta-sigma modulation it looks like since the microphone basically is an ADC, and that as such mics with PDM output may use a Σ‑Δ modulator internally. Also, from Selecting PDM ...
2 votes
2 answers
273 views

Sigma Delta with counter instead of filter

in most applications the 1-bit output datastream of a sigma-delta ADC is converted via a filter. What's the advantage over counting the ones/zeroes and averaging over the results? For a simplified ...
1 vote
1 answer
753 views

SQNR vs SNDR (with regards to Delta Sigma Modulation)

With regard to delta-sigma modulation, I understand that SQNR is the ratio of the signal power within our frequency bandwidth to the noise power within our bandwidth (in-band quantization noise). What ...
1 vote
1 answer
152 views

Interpreting SQNR from a Graph

I'm pretty confused about SQNR/SNR conceptually. I understand that this is a function of the power of the signal to the power of the noise. Is it not the case that we would be able to derive a value ...
2 votes
0 answers
109 views

Adaptive Delta Modulation: Logic for step size control at receiver

I read that in adaptive delta modulation, we have a block for step size control (diagram below) which takes into account the one bit quantizer output in a feedback loop and modulates it, the intent ...
1 vote
1 answer
306 views

How to implement filter poles in noise shaping for ΔΣ modulator?

I am currently stuck trying to implement filter poles to stabilize a ΔΣ modulator. What I think I know is: a noise shaping filter with only complex zeros along the unit circle destabilizes a 1 bit ΔΣ ...
3 votes
1 answer
281 views

What is the difference between the spectra of white Gaussian noise and of a Dirac impulse?

Perhaps it is a basic question, but can anyone explain the difference between the spectra (or power spectral density) of white Gaussian noise and a Dirac delta? They are both constant over the whole ...
3 votes
3 answers
3k views

How would sigma-delta modulation work in software?

I've recently come across this YouTube video that shows a PCM stream being played back via the 1-bit internal "PC Speaker", and after hours of googling I've come to think this is done via Sigma-Delta ...
1 vote
1 answer
244 views

Remove noise introduced while converting a Delta-Sigma Modulated (DSM) signal into a pulse-code modulated (PCM) signal?

I'm writing a tool that converts a dsdiff audio file (dsd64) into a flac audio file (DSM -> PCM). The project is both a programming exercise and a signal processing exercise; I'm learning a lot ...
2 votes
1 answer
2k views

How does the world's simplest sigma-delta DAC work?

I have run into a simple delta-sigma (supposedly, where is the delta part?) DAC implementation utilizing an accumulator and then using the overflow bit as a modulated 1-bit output. From https://www....
1 vote
1 answer
2k views

How to implement a $1$-bit quantizer in Simulink?

I am trying to implement a delta-sigma modulator block diagram in Matlab Simulink but can't find a $1$-bit quantizer (which is required in the modulator) anywhere. Could anyone please tell me how to ...
3 votes
1 answer
1k views

How to plot noise shaped spectrum of First order Incremental Sigma Delta ADC's output?

A little background: This question is about viewing the output spectrum of incremental delta sigma modulators (IDSM). IDSM is a subcategory of general delta sigma modulators where the integrators are ...
5 votes
1 answer
261 views

Does delta-sigma ADC also reduce Gaussian noise on input signal to ADC or just quantization noise?

The motive for posing this questions arises from a difference of analysis between a colleague an myself. Our general environment is in the construction of an analog front-end which takes in signals ...
5 votes
1 answer
384 views

How does Delta-Sigma Modulation convert a 1-bit signal to higher resolution signal?

I've looked at various resources about Delta-Sigma modulators, and I find them fascinating. However, I'm confused on a particular point and and am looking for an explanation. In my understanding, ...
1 vote
0 answers
297 views

Anti-aliasing requirements for a Muxed Sigma-Delta Converter

It seems to be reasonably well accepted that Sigma-Delta ADCs have much looser requirements for the anti-aliasing filter due to both the noise shaping and high modulation frequency. However, it seems ...
2 votes
1 answer
148 views

Is there any difference in Implementing sigma delta modulator using filters and state space model in FPGA?

Sigma delta modulation is extensively used in quantization to reduce quantization noise. In the literature one can see different architecture for example python-deltasigma to implement a modulator. ...
2 votes
1 answer
1k views

Why use a 1-bit ADC in a Sigma Delta Modulator?

When looking at the discrete model of a Sigma-Delta Modulator as shown below, we can see that the quantizer is modelled as a white-noise source $e[n]$. From this model, we can derive the noise shaping ...
1 vote
0 answers
69 views

Sigma Delta Sampling

I am using a Sigma Delta ADC and really understood the working of it I need to sample a signal at 8.5 Mhz. The SD ADC has a Demodulator and decimating FIR filter The Oversampling ratio options are 32/...
0 votes
1 answer
785 views

Power spectral density of sigma-delta modulator

I am simulating a 3rd order SDM and I want to plot the PSD of the output. As you may know, the output is a sequence of pulses ranging from -3 to +4. The number of samples is $N$. The way I ...
1 vote
1 answer
343 views

why does my integrator perform noise shaping?

I am designing (in matlab) a simple system with a DC signal at 0 Hz and some added noise. I am performing a differentiation of the signal (by simply subtracting the last values from each other), next ...
1 vote
1 answer
882 views

Is there a relation between the dead zone of sigma delta modulator and filter order?

This question refers to the link https://pure.tue.nl/ws/portalfiles/portal/1546321/521243.pdf. In chapter 4 it discusses the topic of dead zone, which appears in the delta sigma modulator. Dead zone ...