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# 2nd Order Sigma

64 Threads found on edaboard.com: 2nd Order Sigma

## Attenuation of the fundamental on a Sigma-Delta ADCm

Hello everybody! Recently I have designed a 2nd order Incremental sigma-Delta ADC. I have two main concerns about my design: 1 - The goal was achieving at least 14 bits, but unfortunately after realizing the FFT in order to obtain the outuput spectrum, the fundamental is attenuated by 20 dB. I don't know which reasons can (...)

## 2nd order Delta Sigma Modulator

I am creating a second order delta sigma modulator for a fractional n pll. First I created the first order one. It worked ok when I removed the output flip flop that had to act as a comparator. Of course there's some sort of comparator glue logic. However it is combinational circuit. I wrote a code in matlab and it worked fine, designed the (...)

## Questions about the noise fllor of the 2nd delta-sigma modulator

Hi~~Everybody, Recently, I have designed a second-order sigma-delta modulator using the CIFB architecture. The fin = 1KHz, fs = 1MHz, and Vin = 1V. In the first, I use the Matlab to simulate its function. The output spectrum shows that the noise floor at dc frequency is about -120dB. But when I use the actual devices of the OPA, t

## Plz help me to simulate CMOS Source-degeneration Gm-cell with NIC circuit in Virtuos

This Source degeneration Gm-cell with negative-impedance-compensation(NIC) technique is used to design loop-filter for 2nd order sigma Delta ADC. I dont know what are the parameters/specifications needed for the design of the ADC. Also i need input parameter values like Vsin, Vref, Vss for this Source-degeneration Gm-cell. I am using (...)

## reduction in the SNR after output passed through CIC filter

I have an ideal 2nd order 1-bit (OSR=2048) sigma delta modulator. The SNR of its output is 145dB Unlikely. How do you determine SNR? My SD books don't grant 145 dB SNR for 2nd order and OSR 2048. If the ADC had this SNR, it won't reproduced by 19 bit output length.

## Problem about the PSD of delta sigma modulator

my 2nd order DSM simulink model: I would like to ask how can i get the PSD of DSM like this? Thank you for your help

## Summation Point Movement in CT-DSM

See a left block diagram in attached first figure. This is a simple 2nd-order continuous time delta-sigma ADC of Feedback structure with a feedback path for excessive loop delay compensation. This compensation path is implemented by DAC3. In this block diagram, I assume passive summation before quantizer. So gain K is required before (...)

## PSD of sigma delta problem

hello All , I have a problem of getting the PSD plot of 2nd order switched cap sigma delta the opamps, switches are designed using veriloga. the input is taken every 0.1s using a reset switch on the9242792428 integration cap (incremental ADC) vref= +-0.5 , vin=+-.216 (DC input) OSR = fs/2fo f

## Sigma delta High level Design

hi all, first ,i put the design of 2nd order sigma delta ADC on matlab (simulink) to make high level design and now i want to know how can i get SNR from Simulink model (how to plot SNR). actually, i have an idea that i can get output data from simulink and get SNR in Workspace with equations of schreier toolbox, but i don't know how can i (...)

## 2nd order delta sigma modulator

Hi, I need verilog code for 2nd order digital delta sigma modulator. any help would be appreciated. Thanks, Sree

## Modulator coefficeints and Delta Sigma Toolbox for matlab

Regard to everyone, Here is the problem: Currently I design a 2nd order, delta sigma modulator with CIFF architecture using Schreirer's Delta sigma Toolbox for matlab, and there is one thing that confuses me. When I get scaled coefficients which provide satisfactory NTF and simulate architecture with Simlink, input of (...)

Hy moylando, I am interested on this instability issue of SD modulators. I am having the same problem for a 2nd-order continuous-time modulator, however for higher amplitudes (-3dBFS). I am also using the same DC gain and constant time for both integrators. Anyone could provide some comments on this?

## 2nd Order noise shaping with sigma delta ADC

Hi all, I am working on a sigma delta adc which should give 2nd order noise shaping (40dB per Decade), but i only see 1st order noise shaping(20dB per Decade). Any pointers as to where might the problem lie? I am working in current mode continous time domain.

## digital filter for sigma delta modulator

Good day everyone, I am Patrick. I am an undergraduate student taking my thesis. My group's topic is about the 2nd order sigma delta modulator. My task for this group is to design the digital far as I know, The purpose of the digital filter is to remove the quantization noise that has been pushed to the higher frequency.Thus, improving

2nd order sigma delta ADC: ADC filter section: updown counter and accumulator the filter stage1 after comparator 1 uses x = x + xx * (n - i +1) where xx is comp1 output and x is output of filter and 1

## filter section in delta sigma ADC

In the 2nd order sigma delta (mesh architecture) document "ROBERT AND DEVAL: SECOND-order INCREMENTAL A/D CONVERTER" , up-down counter approach to implement filter section (page 738 and 739) the filter stage1 after comparator 1 uses x = x + xx * (n - i +1) where xx is comp1 output and x is output of filter and 1

## CT sigma delta 2nd order

hi all im doing my proj sig del CT fs=6.144Mhz signal bandwidth is 24000 Hz order 2 Nrz pulse feedback 1 bit quantizer im implemnting ota in 180 nm tech vdd=1.8 vss=0 i designed the ota for input common mode at 0.9v wat shud be the input given for the modulator. A sin wave with .9 dc and some ac on it ? 0r A sin

## distortion (INL) problem in sigma delta modulator

Hi, I designed 2nd order sigma-delta modulator (1bit), and made chip, and measuring now. I use FPGA after modulator output. the FPGA is used for sinc3 decimation filter (16bit out). I have a distortion problem for measurement. test condition; VDD=3V, VSS=0V, VREF+=3V, VREF-=0V, VCOM=0.4*VDD(from external) fclk=100k, 250k, 500k (...)

## Question regarding design of sigma delta

Hi, I am working on design of single loop sigma delta modulator and for that I am using 2nd order CIFB architecture. My question is do we need to have gain stage before delayed integrator in this structure? I did put two gain stage b4 each of the integrator because I was not getting proper output at each integrator output(which according to (...)

## what actually a linear OTA implies

designing a sigma delta 2nd order...CIFF architecture.... in literatures they hav suggested to use more linear and low noise first integrator for better they said first integrator is a power hungry one... bt where the difference in design of low noise cum low power OTA and other OTAs lies... both integrators power is det