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149 Threads found on Feedback Compensation
I have a problem with converting analog low pass RC filter into digital one. My goal is to realize digital feedback loop compensation in software. To begin with, i decided to do some training with the simplest RC filter. The low pass filter is built with R = 1000Ω resistor and C = 1?F capacitor. First i wrote the transfer function as G(s) = 1
Before designing the feedback amplifier, you would make a specification. Load impedance range, amplifier DC and AC characteristic (either gain versus frequency or characterized in time domain), intended accuracy. Presently you have a relative low, frequency independent loop gain (P controller). The gain won't suffice to cancel DC errors but can
Are you talking about random fluctuations or a reproducible step response? In the latter case, we would look at voltage controller loop gain and loop compensation, loop bandwidth and phase margin. They are probably affected when changing feedback resistors.
In an op amp you need to provide compensation so the amp is stable with a closed loop resistive negative feedback. This is commonly done by add a dominant 1-pole capacitive rolloff (6-dB/octave) starting at a low frequency using a miller capacitor internally so that there is good phase margin as the open-loop gain goes to 1. The multiplication of
hi, What type of feedback amplifier (type-2,type-3 or PI) is used in a pure sine wave inverter? Suppose an inverter consists of a h-bridge and a low frequency iron core toroidal transformer. H-bridge is derived by sinusoidally modulated PWM (20KHz). At the secondary of the transformer there is a filter to get filtered 220v sine wave. The outp
The difference between compensated and uncompensated operational amplifiers seems to be related to the gain at phase difference of -180 degrees. For compensated amplifiers, the gain is less than 0dB which means that the amplifier shall never become unstable. However, in closed loop depending on load type and parasitics, the closed loop bode plot ma
Hi, Lately I'm reading a book on (audio) amplifier design. I have some questions about the Miller capacitor in the attached schematic. From this audio book I read: "The global (overall) feedback factor at low frequencies is sufficient to linearise the VAS, while at high frequencies shunt negative feedback through Cdom conveniently takes ove
Hi, sorry to jump in your post. but i would like to know how to implement feedback voltage compensation by modifying the sine look up table. thanks
Above 45 is a good goal to aim for. Once you start designing converters you will find that it isn't always that easy depending on the topology you are using. I may take considerable analysis, tweaking and actual measurement with a FRA to establish acceptable feedback compensation.
Looking at the schematic the 4.7 ohm gate resistor is usually 15 to 18 ohms. But i do not think this would cause the fet to burn out. The 7812 regulator should be 7815 to give you a little safety room for switching the fet off and on. The feedback system is a cobbled up mess. It may be causing oscillation and heating the fets up. An oscillosco
You do not make the output resistance "more bigger" (higher). Instead for more gain you make the negative feedback resistance higher. An opamp has a frequency compensation capacitor to reduce the gain at high frequencies so that its phase shift does not cause oscillation when negative feedback is applied then at high gain the bandwid
Circuit 1 is unstable without additional feedback loop compensation. Circuit 2 has errors, as already mentioned. Circuit 3 needs darlington transistors or additional current gain for high output current. Consider OP output voltage range and required supply.
As my attached picture, if we have negative feedback system, we should make unity gain be within -180 phase not to oscillate our system, considering the number of pole in amp. And I think, upper unity gain frequency, my Aol(in the picture) already has -180 phase because amp has negative gain. so without considering the number of pole in amp,
Hi, I hope this is a sketch only. There are some issues. It looks like you connected the feedback path on the Gnd connection of the scope... The compensation of the feedback OPAMP is dubious, it seems to be made for low gain setting, but your Opamp has no (local) feedback. Is it correct that the feedback (...)
As a general concept, you want to configure the internal phototransistor to respond to the internal led, so that it delivers the correct volt level to the feedback pin. You must create the proper amount of current going through the led. If output voltage changes, then it must cause led brightness to change. In regard to the phototransistor, you i
An opamp has extremely high gain at DC and low frequencies of 50 thousand to a few million. Because the transistor circuit causes phase shift and delays at high frequencies then a compensation capacitor is used to roll off the gain at high frequencies so that negative feedback does not cause oscillation. The gain begins to roll off at about 10Hz.
Presumed there's a resistor to ground completing the feedback network, it's an amplifier with PI characteristic and surely a valid OP configuration. You should show the complete OP circuit. The point that may confused you is that due to the integrator behavior, the circuit needs an external feedback loop to reach a stable non-saturated operation
Hello, We have got a contractor to do a 100W flyback led driver for us, and we believe that he has not done a very good job. The circuit works but we believe that its performance is compromised in the way that he has done it. The circuit schematic and LTspice simulation are attached. He has used an external current sense error amplifier wi
The LTC6101 model is apparently instabble with larger Rin values due insufficient compensation of the feedback amplifier. No idea if the effect occurs with the real IC.
Hi, Can any one suggest me to remove the poles in CMFB circuit loop in differential opamp. This poles are appeared due to the filter feedback network. The CMFB circuit has shown below, and Loop gain and phse shift. I noticed that SR did not change in the Filter due to instability of CMFB. 117712