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Why in RC integrator circuits , Caps are connected sometimes to supply voltage instead of ground ?
Thanks. One issue is that the output of the integrator is vdd or 0, since there is no dc feedback to control it, which gives a wrong simulation data.
Hi, The signal and noise transfer function of a continuous time first-order delta sigma modulator using an simple active RC integrator both have a pole at 1/RC. The transfer functions are attached.115966 I was wondering, ideally, why can't we make RC very small, so the quantization noise is lower in the band of interest?
caps are used to act a a temporary or transient current shunt to noise voltage, the current is an integrator of voltage, also a DC block or RF coupler or an impedance vs f filter for bandwidth control. There are millions of caps, with dozens of attributes, that define them uniquely. pick 1 and ask for details with example schematic if that he
Hi everyone, Can someone suggest some papers or books or insight into the calculations for integrated vs. non-integrator noise components of a CTIA? I can't seem to find much of anything online... Thanks in advance!
103527Hi All, I am studying the working of Delta Sigma(DS) and Incremental Delta Sigma ADCs. I am trying to implement those in Simulink. For DS I am getting proper output with noise shaping and good SNR. But when I am using the same structure for IDS with the reset connected to integrator, I am getting third and fifth harmonics
Hi all, I'm working on an optical sensor and am looking to increase my SNR. I've constructed a circuit to cancel out LED emitter noise with feedback control. PDref monitors just the emitter, while PDsig carries the sensor signal + emitter noise. Feedback consists of integrator -> JFET VCR -> current divider. Please see attached circuit. LT (...)
Hi, guy, I need to design a large off-chip capacitor as the feedback capacitor of a on-chip current integrator for a large input current (over 10uA). However, I also need to use the same integrator to detection low level current (1pA). I know the input node Iin is very sensitive to noise. However, pad connection to (...)
Hi, I am doing a 3rd-order 2-bit CIFF DSM, I used Scherier's delta-sigma ToolBox to do the system design, ideally i can get 130dB SQNR with OSR=128. but i found the b1 and c1 coefficients are small so that the capacitors for the 1st stage integrator are very large when doing thermal noise budgeting. for this reason i increased the OSR to 256, this
CIC uses modular arithmetic, overflow is by design. All CIC stages must have the minimal bitwidths according to CIC theory, then the output will be correct despite of integrator overflow.
Well the above one is the basic block diagram of a first order sigma delta ADC. Now I am trying to implement that in hardware. Here's the image that I saw regarding the implementation in hardware. I have few doubts h
Hi Jack, A sigma delta modulator consists of one feedback loop around an integrator and a quantizer. This integrator (since you have 1/S therefore continuous) producing a low pass filtering of the input signal and a high pass filtering of the quantization noise which is injected at the quantizer, hense noise shaping the (...)
Hi All, I am working on a noise dosimeter design. The hard part is that I can only use analog circuit... I got stuck in the time integrator part. My circuit went through amplifier, A-weighting filter, RMS, exponet, and threshold all using analog. So, I can take out all the signal below 90db. Now I don't know how to build (a noise (...)
Hi Everyone. I am implementing a Kalman filter for an accelerometer. As you know,the accelerometer can be modeled as a Random Walk process and the output of a random walk process is assumed to be coming out of an integrator driven by white noise. This is described in "Random signals and applied kalman filtering, Brown,Hwang" chapter 2&5. The book
integrators can be one type of Low Pass Filter. They are used by some ADC or in wave shaping. An integrator circuit produces a steadily changing output voltage for a constant input voltage. Similarly, the Differentiators are High Pass filters. A differentiator circuit produces a constant output voltage for a steadily changing input voltage. Adder
75140 Inserted picture is the lossy-integrator in my circuit. To precisely run Simulink, I would like to calculate input referred noise for this lossy integrator, but I just don't know how to calculate. Can anyone help me to calculate the input referred noise please?
I found a good article in 'analog dialog' from 1967 discussing the various errors and design issues with a Operational Amplifier integrator circuit. But what about the Digital integrator. What would be the errors involved with a Forward Euler vs. Runge-Kutta etc.. ---------- Post added at 10:22 ---------- Previous post
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 (...)
HI ALL i hesitated if this issue belong to this section but i will be very happy if some one of u will help me i need to create sigma delta modulator for some application. there is any section in the modulator that named noise shaping - it means that after oversampling signal we make integrator loops to the quantization noise and move (...)
An option is to use a type-2 PLL (one integrator in the loop filter). The output of the VCO is inquadrature with the input over the whole lock range. Possible design issues to consider: acquisition time, tracking if the frequency changes quickly, phase noise, wide-range VCO. The last one can be solved with a frequency conversion, i.e., insead of
Hello naderi, In a delta sigma modulator, it is well-known that only DAC and the first integrator can contribute to the output noise. It can also be tested by behavioral simulators such as Matlab and verilog-A. I found that transient noise analysis is not match with noise analysis. An experienced designer told me that he
Hello, Hi, I need a favor from you. I am designing SC integrator kind of similar circuit but, instead of cap using big resistor. I would like to know how to analysis the circuit in terms of noise Analysis, apart from transient simulation, anything simulation like mentioned SwitCap simulator. Please, guide me on
I am really facing problem while doing noise simulation of Continuous TIme integrator. I am using Spectre simulatior Which is correct method to do noise simulation ? noise in ADE or PSS, PAC and PnoiseThey give same result as far as small signal operation. You post completely same question in the (...)
Sampled Mode exists in PAC and PXF of Cadence Spectre. This mode is similar to "timedomain" mode in Pnoise Analysis of Cadence Spectre. The Designer's Guide Community Forum - switched capacitor integrator noise simulation results However I can't get reasonable results for
Hello all, What can limit the input signal level for a delta sigma modulator? I used an example given in the delta-sigma toolbox from Matlab and optimized a 3rd-order NTF for: -Continuous-time with RZ DAC -all poles at DC. -out-of-band noise Hinf=1.7 -BW = 20kHz -OSR = 128 -cascaded-integrator-feedback (CIFB) structure. (fs=5.12MHz, U
An op-amp is just that, an op-amp. In the real world reducing the upper frequency gain by turning the circuit into an integrator reduces the wideband noise at the output. A differentiator would increase the noise at the output and its function is avoided as far as possible. Frank
I designed a 2-1 sigma-delta modulator and found fft issue I don't understand. My sim has 2 steps: 1) run "tran" analysis in spectre (select "Transient noise" option) 2) read data from modulator output to matlab and do fft in matlab I used 2 different sampling capacitors (1pF, 4pF) for the first integrator and other parameter (fclk, fsample, N
Yes. The real cut-off frequency of this integrator is ARC, as you can derive by simple transfer function analysis. Of course, the price you pay is increase in noise and power consumption.
Hi, I try to match model of first order sigma delta to spectre simulation results, but they disagree! First figure attached is first order sigma-delta model (comparator shown as a summing node and noise source N(s)). Can solve to get: Y = N/(1+H) + H*X/(1+H) where H=K/s So if K/s >> 1, then: Y ~ sN/K + X This says to me that to
I figured out that the NTF is indeed quite flat in that band. It is a 3rd order modulator with cascaded integrator and feed-forward
Hi, Can any one tell how to determine requirements of of the amplifier of single stage Sigma Delta modulator. It is clear that sampling frequency and maximum input range will determine GBW and SR of amplifier. But how to determine required DC gain, offset noise. If we have as task to make ADC with certain resolution let's for example 16 b
Hi, Can any one help in doing in noise simulation of SC integrator - part of a incremental sigma-delta ADC? Any good reference or simulation type details will help a lot. Thanks Sanku
the output would be zero Not exactly. It's still noise, with 1/f spectral density, like semiconductor flicker noise. And strictly spoken, an integrator has possibly a DC offset.
the noise in sigma-delta modulator loop is shapped by preceding integrators, for example the noise on the output of the first integrator is first-order shapped and the noise on the output of the second integrator sencond-order shapped. but the noise to input of sigma-delta (...)
Hi all, I come across this paper and would like to try it out on Simulink. With regards to the block diagram, should I use the Discrete-Time integrator from Simulink to represent Discrete integrator in the blo
Hi, I've encountered some problems in designing a 2nd order SDM. the integrator outputs looks fine, however noise shaping did not come out (as Attachment file) can someone please tell what cause this happen? thx
to pfd001: How to use integrator command? In the analog design enviornment, you can find the calculator in the tools. In the calculator, you can use the integrate
Depending on how your integrator is build up! I suggest it is built with an opamp. Then simple short with a switch between the cap instead of the output.
Hi, all I noticed for some SD ADC designs, ppl use CDS to decrease integrator leakage and flicker noise. For those of designs that circuit noises are the dominant noise sources (i.e. quantization noise is not so obvious), how can I model flicker noise and white noise (...)
Your problem is with reference source, that you use to shift the output DC level of triangle wave. In histeresys block - switching occurs between two states, in middle is DC level In integrator block - output integrates the noise of reference source (only elimine noise with zero mean) Improve it. Try a large capacitor to (...)
Hi, I have a stupid question about integrator noise.. Say an OTA has an input-referred noise Vn at it's positive input, and be connected into integrator, the transfer function (1/SRC) has infinite gain at DC, ideally. So what would input-referred noise Vn be at OTA's output? If I give input a (...)
It is very difficult to say in a simple paragraph. However, the key is the signal is almost untoched and noise is shaped by inserting integrator in front of comparator (Assumed that LP)
My question is how to extract the nonlinearity of a Gm-C integrator, i.e. THD (total Harmonic Distortion). SNR (Signal-to-noise Ratio) and SDR (Signal-to-Distortion ratio)? As my knowledge, these perforamnces are from the FFT of a signal. Does it need a tranisent simulation??? In some literatures, the performances 1dB compression and IP3 can
My question is how to extract the nonlinearity of a Gm-C integrator, i.e. THD (total Harmonic Distortion). SNR (Signal-to-noise Ratio) and SDR (Signal-to-Distortion ratio)? As my knowledge, these perforamnces are from the FFT of a signal. Does it need a tranisent simulation??? In some literatures, the performances 1dB compression and IP3 c
hi guys, I've been working on a sc integrator for a 16bit sigma-delta ADC. while when i doing the bootstrap switches, the charge injection noise and clock feedthrough give a lot of noise, even the charge injection can be common mode rejected, there is still body effects (nonlinear) and clock feedthrough. does anyone who did this (...)
The characteristic parameters of op amp is relative to the loading and feedback factors of integrator. In the meanwhile, the settling accuracy and noise requriement are the factor to determine the op amp. I think the design of op is the core design for SCF.
why not reduce ur total capacitance ? why did u choose 9.6pF for ur integrator ? for noise issue, or matching issue? by the way, what do u mean "5-bit coarse quantization", I have not heard about that term from books, is it a new technique ?
In contrast to sigma-delta modulators, delta modulators have their integrator(s) in the feedback path and not in it forward path ( input - integrators - adc) . Therefore, no noise-shaping is done. Hence, it isn't usefull for oversampling converters.
the 4Kohm resistor has 2 reasons: 1. it's the reason described by petarpav. 2. if you use internal ref, the 4Kohm resistor and external cap (common 100nF), make the noise rejection of internal refference. (work as RC integrator)
just as title said.I want to make a noise analysis of a integrator by hspice.Can the following sentence works it out? .noise V(out) Is DEC 10 100 100Meg and second a analysis result in the *.lis file,there are: **** total output noise voltage = 3.2205m volts **** total equivalent input (...)