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35 Threads found on edaboard.com: Feedback Cancellation
hi everyone, i'm working in my thesis named acoustic feedback cancellation system in Matlab. i have 3 most important doubts , if someone can help me with this i really would apreciate it: 1. which software is better for this, PUREDATA OR MATLAB. 2. is it better the use of adaptive filters or the implementation of notch filters?. 3.HEEEEEEEEEEL
I designed an electret microphone (single ended) amplifier (recommended by the chip itself) which works well, only if the speaker is very far to the source. The reason is that audio feedback is worse when mic and speaker is close to each other. The attached design below is an input to the codec (WM8991 if you're aware). But if any of you can help f
Would any people like to introduce me some good book or material,which describe the detail of DC offset compensation feedback of multistage-amplifier? I am currently working on high-speed limiting amplifier, however still not clear about the usage of the DC feed-back. Personally, I think it make the circuit operating point insensible to pr
Hello all, we would greatly appreciate if the respected auditorium of this forum could provide us with their feedback on the noise reduction techniques we have developed. Please download our demo noise cancellation software at: Thank you very much and we are looking forward for your feedback!
Guys, Can someone explain me what are the advanges & disadvantages of using the Feedforward & feedback Offset Voltage cancellation in Circuit design. Thanks, suria3
Hello All, I need to implement a simple voice amplifier. I have no flexibility on microphone or speaker location and I'm affraid I'll have acoustic feedback (howling). Is there some purely analog method or IC for acoustic echo cancellation? I wonder about hands free telephone operation.... Have they such kind of circuit? Thanks in adv
Guys, Currently I'm doing research in Optical Receiver design consist of Transimpedance Amplifier and Limiting amplifier. I noticed that in the fully differential Transimpedance amplifier circuit design, there is a offset compensator at the output of the differential TIA and feedback to the dummy TIA.Then when it goes to the next stage of cascad
In the article "lineariztion technique using digital cartesian loop transmitter" , the author said "as with all feedback systems, its performance is limited by the delay around the loop and hence the linearity improvement which can be obtained depends upon the bandwidth over which the feedback must operate." I don't know the "bandwidth" is RF bandw
using negative feedback in baseband amplifiers reduces the DC-offset. does the accuracy of this DC-offset cancellation depend on the magnitude of the input DC-offset voltage? I mean, the higher the input DC-offset voltage is, the better the negative feedback works?
someone tell me that the dc offset is detemined by the layout qualitfication. I think this will be controlled not solve,but how? someone tell me that there are some digital calibration technique to control the bias?but this maybe too complicated a technique. can anyone offer some details of the dc offset calibration technique in the picture.
A DC offset cancellation circuit uses a feedback loop. The bandwidth of this loop can reshape the bandwidth of your amplifier. The design of the loop needs careful design in terms of delay, frequency response and stability.
I think I understand what you are saying, but the amount of capacitance required would depend on the gain in order to just cancel and not cause oscillation. I have used positive capacitive feedback to remove the gate capacitance of fets, the capacitance of a photodiode, and the stray capacitance of compensation networks but it relies on having a c
In direct convertion (Zero-IF) RX system RX DC offset must removed. In such an WLAN receiver high pass filter with low cornner frequendcy is often used to remove the DC offset. There are two ways to realize the high pass filter. (1) using AC couple directly to remove the DC offset. (2) using a negitive feedback with low pass filter to extract the D
Dear sir/madam i need matlab coding for adaptive feedback noise cancellation in hearing aids using adaptive filter. the input as a speech signal.
HI....I need matlab codes for mutiple feedback successive interference cancellation in MU-MIMO...... can anybody help ?waitin 4 reply.....need materials to study BER performance too..................
DC offset inputs do not affect gain. If you apply DC offset to a differential amp, the main factor is the equivalent resistance in feedback ratio or input attenuator ratio is constant. If the offset only introduces a DC signal from a relatively constant impedance source to null the offset ( in a feedback loop), then the gain is constant.
Of course, chrutschow is right - and his arguments hold also for the case that there is only capacitive feedback (integrator applications). Another remark: It seems that the presented simulation results are not correct (not enough simulation steps in the active region).
Hello, I am currently trying to remove a peak in the noise spectrum of a particular control variable. The noise is around 40dB above the noise floor, peaking at ~1 MHz with a width of ~300 kHz. I would like to reduce the noise in this region by ~40 dB; the rest of the noise spectrum is less important so I can tolerate noise peaking elsewhere.
Hello, Folks, I am looking for a pair of Active Noise cancellation (ANC) headphones that could cancel human speaking. But almost all headphones in the market are just cancelling the low-frequency noises such as engine or fan. I do not understand why the higher-frequency parts of human voices could not be cancelled since ear hearing spectrum j
Are you sure that you need a asynchronous comparator? Usually the comparators used in the ADCs work synchronously with the clock signal. If it is a synchronous comparator (controlled by a clk signal) you should use a regenerative structure, which employs positive feedback. There are several known offset cancellation techniques. If it is asyn
can it be connected in feedback mode other than connecting two inputs to vcm
The limiting amplfier is normally multi-stage cascaded. This required a DC negative feedback to provide offset cancellation. My question is how we get the relationship between the lower corner frequency of the amplifier and the R, C parameters? Why it is related with the gain of the amplfier stages? What is the impact if the lower corner fr
First, I advise you to read papers about SAR ADCs with specifications similar to your's (I'm sure you can find this). The comparator to use should be a "latched comparator", using positive feedback. The offset voltage can be reduced by using pre-amplifier stages before the latched comparator, where offset cancellation can be performed (OOS/IOS -
WELL... according to my knowledge you have two solutions... 1)feedback to make the drain currents in the Nmos and Pmos the same because that missmatch will cause bad CMRR 2)the other solution is to decrease the common mode gain that will decrease the difference i hope that i helped u THANX
Hi, I'm desigining a Transimpedance amplifier with the bandpass response, which means the differential output of the TIA is feedback to the input of the TIA for DC cancellation purpose. My question is, how do I calculate input referred rms noise of the TIA in Cadence. I understand that for the forward TIA design (LPF response), i can run the noi
Hi guys, I'm working on a dc cancellation circuit in a optical receiver circuit. Currently, i'm facing a problem in designing a low noise opamp for my feedback circuit. The function of this feedback circuit is to compare the dc voltage at the positive and negative input terminal of the opamp to be 1.2V and substract the input dc current (...)
Thank you for the feedback. I was starting to think that nobody here ever worked on a baseband chip before and that they must be designed by elves in a magical kingdom. :)
Of course, you can measure the open-loop gain of an opamp vs. frequency. However, take care to use a proper bias point (offset cancellation) and an input signal which does not saturate the amplifier. Normally, a special test set up is used for this purpose which enables dc feedback and no ac feedback.
I wander whether you drawed the schematic completely. I designed a fourth order filter with DC offset cancellation.the feedback block acts as a LPF to extract the dc signal of the output. And the BW of the LPF is very the value of R and C is very large. For the main signal path,the load is only R. when you design the amplifier, This shoul
Hello, for my Diploma Thesis i have to design a low noise NF amplifier in CMOS Technology. I chose a folded cascode OTA with autozeroing and fully differential design. I read the paper "circuit techniques for reducing the effects of op-amp imperfections.." from Enz and Temes. I wonder about a few things: 1. Both, the main amplifier and t
I need to connect in series two high gain fully differential opamps. They both have common mode feedback with high loop gain. Monte Carlo simulation show that due to mismatch there is a small DC offset at the output of 1st opamp. This offset is amplified as differential signal by the 2nd opamp. Is there a good solution for this problem? Thank
hi,Eb/N0 VS BER...modulation s BPSK... And channel assumption s rayleigh fading...after that have to work for Multiple feedback SIC.....
Putting several opAmps in parallel with a common feedback (nor with individual feedback) usually won't work, as each amp will work a little bit different (at least in reality), so the outputs just fight against each other (output contention). If you need the drive capability, just use one opAmp and add an appropriate driver.
I agree there should be a mathematical model for calculating this. I have always done it by experience as you stated, comparing loudness of reflections to direct sound. But without reflections and relative size of room to distance from speaker, it is impossible. But I can always tell when someone is TOO far from their mic. ;) With the user emitt
Ruby, in most cases an integrator is not used as a "stand-alone" circuit but as a part of an overall closed-loop with negative dc feedback (e.g. filters). In this case, dc offset shouldn`t be a problem. Therefore, the answer to chrutschow`s question is important: What is the overall function?