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592 Threads found on edaboard.com: Delta Sigma Adc
Hi, Can anybody please suggest me how to implement this block diagram using Capacitors? I tried but messed up because when I try with one gain coefficient, it changes the already calculated capacitance for other branch. 136191 Thanks
Hi Altruists, I need to design an incremental sigma delta adc (OSR=500) where I need to implement a CoI Filter. From literature study i found that this CoI filter is actually same as CIC but without the comb part for CIC. I need to write a code in Verilog (or Verilog A) for CoI Filter. I dont have so much deep knowledge on CIC. I checked (...)
hi I wanted to know that can a sigma delta adc will handle multiple inputs from different source by using a mux
Hi Folks, I need to design a 1 bit DAC for sigma delta modulator. Can anybody please suggest me some architecture for dac design? For incremental delta sigma the dac needs to provide three state ( two states from two quantizer levels and one state for input level). How is it possible with 1 bit DAC?
In addition, there are two flavor of delta sigma adc. Discrete time and continuous time. Continuous time has inherent anti-aliasing.
The DS adc(delta sigma adc) output will be equal to the input*STF(signal transfer function) + quantization error*NTF(noise transfer function). At the output, the data needs to passed through a low pass filter to filter out the shaped noise. In most practical cases, the STF is almost one in the signal bandwidth. Thus, there (...)
Hi, I need help to determine the op amp gain required to match certain adc specifications. I need to design a delta sigma 14 bit adc and need to find out required op-amp gain for the integrator design. Is there any certain formula to find out that
Hi, You are desgning the is a clocked system, so you should know after how much clock cycles the output is valid. (Just to be sure: you don't talk about delta sigma adc?) Klaus
Hi, I need a book or reference that discusses the adc's Calibration .... what is it ? and why is it done ? and how ? and does it differ from an adc type to another ? Thxx
hi I would like to measure the ENOB of a sigma-delta adc on Cadence Virtuoso. what are the steps to be done ? do i need MATLAB ?
Hello, I've read around extensively about FFT setup for a sigma delta adc and I'm not sure if I'm not setting it up properly . my current setup for a first order sigma delta adc sampling frequency : 38.4 kHz (for the adc and FFT setup) FFT bins : 65536 input (...)
Many people use SAR adc, some stick to delta-sigma and some like pipelined adc while designing signal conditioning circuit for SoC or for IoT application Chip. What is your view on this? Which one you will pick and why? There are hell lot of literatu
Dear All, Could you please tell me what's the relationship between OSR and ELD in continous-time sigma-delta adc? And why lower OSR is more sensitive to ELD? Thanks a lot! best, Ken
Attached circuit shows Feedback DAC of CT-DSM-adc(Continuous Time delta sigma adc). What type of DAC do you think this DAC is, Current(Fig.4.5) or Resistive(Fig.4.3) ? I think this DAC is current type same as Fig.4.5. Here I have two questions. What purpose do you think circuits inside red rectangular have ? (...)
I am working on sigma delta modulators. I came to know that the MIXMODEST presentation/document provides an excellent description of the factors related to the design of sigma delta modulators. the link given below does not work. Can anyone forward me the docu
Why are anti-aliasing and low pass filters not always integrated into the data converters? Hardly possible, in general. With the exception of oversampling adc (sigma-delta type) that mostly have a high order low-pass filter built in. They can be operated with only a simple low-pass filter removing input signal components above half
Hello, First...sorry for my English and bad grammar. I'm not native speaker. I need to measure dc voltage signal (or get average value from slow periodic signal to 100Hz - but it's not neccesary) with biggest resolution as possible. Dynamic range is 0.2-4.8V. Let' s say 500uV resolution is neccesary and anything better like down to 100uV reso
I am designing a 3rd order Continuous time adc , with 1 MHz Bandwidth ,32 OSR and 3 level Comparator. I have a question regarding the coefficient values. I used the equation: coefficient * fs = 1/(R*C) However, since the coefficient has 3 or 4 points precision (for instance: coeff = 0.0805 ) Assuming So the p
I have been working in the design of a 3rd order sigma delta analog to digital converter. right now I am concerned with the implementation of the digital part, the digital filter & the decimation filter. Any help? as i can't find a resource that illustrates the link between the analog part of the adc & the digital one.
I am working on a 3rd order, 1 MHz sigma delta adc with the following Specs 3 level quantizer and OSR = 32. I am facing a linearity problem that i don't know how to fix it. The system achieved max SQNR = 69 dB at Vin Full Scale and Max Frequency (i.e: Fin = Fb) The following figure shows the PSD: 1
Hi Friends, I am wondering how sigma delta adc's work with a 1 bit Comparator. I went through some articles and I have a rough idea of its architecture. There's a 1 bit comparator and the input is sampled many more times than the Nyquist rate. Suppose I have a 0 to 10V measuring sigma delta (...)
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 cause this (...)
1. The output is a binary digital signal, which is normally represented by 0s and 1s. The actual level depends upon the logic being used. 2. The output of the decimator is indeed a digital signal. The digital filter and decimator converts the serial stream of 0s and 1s with coarse resolution from the sigma delta modulator into the series o
hi i am working on sigma delta adc one query : how to find hte input range for sigma delta modulator for which the adc can work properly please suggest Manissri
Reference previous thread: hi wowee For weigh scale application I recomment you AD7730. I did not counter the problem hat you have ,(my application is unipolar) Totally,I fear to use analog devices sigma delta for my future products ,I think It is better to te
hi my friends I want to design an delta sigma adc, and i need to amount of minimum jitter in my Calculation. what is the amount of jitter in TSMC 0.13 ?
I am designing a 3rd order sigma delta adc with OSR = 32 , Fsampling = 64 MHz, with 1.5 bit comparator. The design is in 0.13um technology. The target peak SNR from the system design (i used Schreier toolbox) was 76 dB. After generating the system coefficients, i verified it on Cadence using ideal components. The system peak SNR was (...)
Is there any way to measure the SNR of signal used in Verilog-AMS models (for ex. sigma delta adc) on cadence environment?
The op amp with the ideal vcvs in the CMFB circuit still affects the sigma delta adc performance greatly!! Could you show how you connected the vcvs-CMFB to your opAmp?
Okay, here's the deal: 1) Learn about coherent sampling. You should use sampling frequencies and input frequencies that are coherent. Meaning that the input frequency should always be exactly on a bin that is computed by FFT to get the most accurate performance measurement. There's more to it but this is an intuitive explanation. If you get this p
1. The discrete Fs numbers are industry standard audio sampling rates. The converter can work at different rates, the essential point is the master clock to fs ratio. 2. The internal fs divider is switched according to the actual BCLK rate. 3. A sigma-delta converter is continuously sampling the input signal and generating the output data str
A strange phenomenon appears when I was testing my sigma delta adc(MASH 2-1 structure, with single bit quantizer at both stages) . The small signal (10mVpeak-peak, 2.9Vpeak-peak as FS value) 1kHz sine wave is used as stimulus to the data converter and 2nd, 3rd, 4th, 5th harmonic distortions can be observed in Audio Precision measurement's (...)
Hi, We are trying to interface Shunt 75mV at 500 Amps AD/DC load to PIC24FJ128GC006 microcontroller, Can we connect shunt directly to Micro controller CH0+ and CH0- pins or do we need any circuit in between. PIC24FJxxxGCyyy series micro controllers have inbuilt 16 bit sigma delta adc. So considering the resolution we think that 0.1 (...)
Hello I have some queries about delta-sigma DAC. 1) basically, it is same with delta-sigma adc, but it consists of digital blocks, such as accumulators. However, how to synchronize the clock with PCM signals from a DSP? Does it need serial communication circuits? 2) I tried to find Simulink (...)
Hi All, This is my first adc and verifying it is proving to be more difficult then actually designing the subblock. I have been able to do a transient simulation in cadence (spectre) and have successfully imported the data into matlab. This is where I'm encountering most of my headache. 1) I'm new at matlab 2)All of the fft examples I've
Hello CHL, While delta-sigma or sigma-delta is in essence an averaging process the oversampling is not the only thing responsible for the ENOB. For example only OSR improves the number ob bits from n to ENOB=n+0.5*log2(OSR). Now this means that for a 5-bit gaing OSR of 1024 is needed. Now if you look at (...)
Hi, Is there any way to simulate the frequency response of digital filters using Cadence Virtuoso? (like AC or PAC analyses done for analog filters) Actually, I am trying to realize a delta-sigma adc in Cadence, which consists of a (digital) decimation filter. Can anybody give any idea how to simulate the performanc
Hi, I need help regarding 2's complement coding scheme to be used on the delta sigma modulator output before feeding to the decimator. Following scheme is suggested in some Lousiana State Univ thesis: convert 1b'0 to -1 = 1111...11, and 1'b1 to +1
Hi..... I have designed and fabricated a 16Bit second order, single bit sigma delta modulator based adc. During testing of adc, when we apply zero volt at the input of adc, sometimes it works fine and sometimes it gives a fixed code of 00FF (hex). Otherwise the adc is working fine. Are (...)
One of these references may help.
Currently, I have designed a second-order sigma-delta adc (fin = 20kHz, fs = 5MHz). In this adc, a 2-bit flash adc was adopted as a quantizer, and a 2-bit DAC was inserted into the feedback signal path. The attached file is the system architecture and the simulated results. 113250 According to the (...)
Paper or Thesis information: T. Thantipwan and N. Wongkomet. "A power-optimized 16-bit 1MS/s nyquist-rate sigma-delta analog-to-digital converter", Chulalongkorn University. To be published. thank a lot ! - - - Updated - - - be badly in need of this paper!!!
hi i am designing a sigma delta adc. \can i keep a osr which is not in powers of 2 eg. 50. will i be able to design a decimation/\cic filter for such a decimation factor?? or is it necesaary to keep \osr in powers of 2???
Dear all, I am trying to design a single-bit first order delta-sigma adc. The architecture that I am using is the very simple single ended ΔΣ modulator. The modulator is supposed to work for audio band signals (20-20KHz). The clock signal that is used is a 2.56MHz pulse. Therefore OSR is 64. Switches that i
Hi guys. nowadays i'm learning delta-sigma adc. i'm too confused because of one problem... 111414 ficture from understanding delta-sigma data converters by Richard Schreier here's the image related to my Q as you can see there's single tone input at 2*10^-3 (normalized frequency) (...)
Hi, Is there any thumb rule to set the Quantization threshold for generating the bitstream while modeling a first order sigma delta adc? I am trying to model a 16 bit SDM adc with a full scale input of of 1Vrms. Thanks, Ranand
Hi, I'm a bit unclear about a decimation filter used in oversampling data converters. Say in a delta sigma adc that has a sampling frequency of 64 MHz, input frequency of 1 MHZ, oversampling equal to (64MHz/(2*1) = 32), and a 1-bit internal adc, the resolution is supposed to be 20 bits. So there would be 64 samples at the (...)
Hi, folks, I am writing an academic paper about micro-watt 1st order sigma-delta adc. The schematic is attached here. I need to know what is the ratio between analog components and digital components. I think that that in a mixed-signal circuit, compared to that of analog components, the digital components power consumption is much lower (...)
Hi, I was wondering if for delta sigma adcs it would be possible to use non-uniform sampling (under sampling) for frequencies higher than the maximum bandwidth of the adc. For example, assuming a delta sigma adc has certain resolution for an input frequency up to X Hz, (...)
Some of this depends on the "ASIC" target foundry flow. A mostly-digital sigma-delta converter is popular (esp. in audio ranges and lower) because almost any cheapo digital flow can support it. Whereas others are needful of high quality matching and linearity in resistors or capacitors, which may not be available or well enough controlled / model