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298 Threads found on Amplifier Phase
I need to make an amplifier which could amplify very small signals (uV) embedded in noise. The frequency of the signal to be amplified is known. The problem is that the signal has too much noise around it. I was told that a lock-in amplifier or phase sensitive detection (demodulation) can solve the problem but i don't know how to make it. (...)
I think that is a stability problem because there is feedback circuit from output to OPAMP and phase shift is not clear. As KlausST said, a AF Power amplifier can be used, they are stable.
The amplifier's phase and gain plot: 136626 When gain=0dB, the phase marge=72, which is stable for the unit gain bandwidth 22.7MHz. However, the phase changes a lot within the unit gain bandwidth, like a sine waveform. In this case, is it acceptable for the phase not monotonically decreasing? Thanks.
Hi, I want to know the differences between low noise and low phase noise amplifier. Thanks in advance
Hi, This is the picture of a mini magnetic amplifier (called ferristor). If one would want to build the ferristor, how he should wind the left hand side windings? My guess is that the left winding, must be two with different phase (wind opposite) so that they can cancel the transformer action from the output winding. So how to wind them? A guess
The PMOSFET is wrongly connected in your schematic. You should also consider that the MOSFET booster circuit is adding gain and reducing phase margin so that the amplifier needs additional frequency compensation to achieve stability.
Load Pull can be used, no doubt. If you consider the oscillator as an Power amplifier, the principal is almost same,so max. power at the right impedance. But.. Load Impedance is also quite deterministic on other specifications of the oscillator such as phase Noise,Drift and Pulling effect.If you would obtain max. power from the oscillator, you may
You see loop gain indicated in an amplifier open loop gain diagram. The point "way down" is unity gain frequency. Feedback factor < 1 is the missing link. Read the text completely beyond the quoted part.
A PI error amplifier would be my first guess. You didn't tell about the phase shifter range. Generally, an additional comparator for positive or negative phase difference and phase reversal switch are required to push the phase difference to the right part of the detector curve.
For an error amplifier, the stability is defined based on the response of the amplifier for a range of sine wave frequencies. However, when we have DC-DC conversion - linear or switching, when the source is pure DC, what is the source of AC frequency at the input of the error amplifier? For the simplest case - converting 12V to 5V (...)
Hi, all. I am trying to measure phase changes according to difference materials. I know the best way is to record applied and measured signal, but due to low sampling rate of ADC and high frequency of input sinusoidal waveform, I can not record them. So, I wonder if there is a way to convert phase to amplitude, so I can easily record them wit
A thin wire has series resistance and series inductance that you do not want in a high current power supply wire to an audio amplifier.
to make analog amplifer, I connect negative feedback and phase shift of amplifier should be below 180 when amp gain is unity gain because if not, output of amp is larger more and more or oscillated. But when that conditions are satisfied, how can i prove that amplifier is not oscillated? for example, at specific frequency, when gain (...)
Hello all, I have a BPSK/QPSK type signal from a transmitter. Carrier frequency is 400 MHz and data rate is 1 Mbps. The BPSK/QPSK signal is to be transmitted to a remote receiver. What type of power amplifier should I use as the output stage?
High frequency phase shifts in an amplifier or opamp cause it to oscillate at a high frequency when negative feedback is added because then the high frequencies produce positive feedback. So the compensation capacitor is added at the VAS stage to cut gain at high frequencies so that the gain is less than one at frequencies where it would oscillate.
However, when we design an inverting amplifier or a charge amplifier, we need a feedback resistor. So, I want to know what kind of things I need to consider when I decide the resistance value. You are asking about two different amplifier topologies in one question, charge amplifier and inverting voltage (...)
Hi guys, I'm current working on electret microphone amplifier. I found two circuits from other thread that are almost similar but with some differences as highlighted in the attached figure. Could anybody explain the differences referring to the figure? Awaiting your valuable response. Thanks. 125315
I want to design a CMOS analog frontend for OPTICAl BIOSENSORS , I want to design it using transimpedance amplifier.... but I didnt find the specifications required for the amplifier i.e: 1)what are the ex of optical biosensor ? and 2) what are their characteristics ? like Gain, Bandwidth , phase Margin , (...)
You bought a Chinese amplifier. We do not know if the IC is a REAL TDA7297 or a poor Chinese copy. Its datasheet says it is made for use in a TV or a portable radio, not in a car. Its speaker is supposed to be 8 ohms, a 4 ohms speaker which is common in cars might burn out the amplifier. You need a car stereo FM transmitter that is commonly sold t
Hello,I would like to control a three phase motor respecting phase order,could you advise on how I can do it,for zero crossing detection I used an operational amplifier as a comparator for detecting the zero crossing level,and I also I want to start from a low speed which could be increased with a push button,I planned to use the TRIAC (...)
Hello, I would like to design a little phase array antenna (for example at 3 GHz), so i need to keep the phase coherence between the patchs. If i buy ,for example, 4 identical amplifiers, one for each patch, do you think that the phase response for each amplifier is the same? thanks a lot Some (...)
Problem you have is when resistors are changed Ic current must not be changed. Resistor 1k can have so high resistance that 270ohm resistor is not needed. In this case temperature stability is lowest possible. Changing resistors you also change the gain and phase of amplifier which may stop oscillating. 10mA current of a divider is a bit high for Q
The feedback factor is larger than unity if it is not a PASSIVE but an ACTIVE feedback path (with another amplifying unit). Example: phase-lead integrator. In this circuit the feedback path consists of an inverting opamp amplifier in series with the integrating capacitor - fed back to the non-inv. opamp termnal. Advantages: The parasitic (...)
I presume "phase angle" means angle of the fundamental and thus involves an analog measurement. You might get off which cheap transformers if you only need an accurate phase angle measurement, relying on a certain degree of transformer matching. Generally I would prefer modern "digital" isolation amplifiers if galvanic isolation is a (...)
The problem is a sloppy representation of the compensator phase characteristic in the Intersil paper. It's normalized to 0 degree phase, means the phase inversion of the inverting amplifier is eliminated. But LTspice shows the actual phase of the inverting amplifier which is the correct (...)
At a frequency < GBW, my phase response dips to 40deg (LHP zero present). ... i.e. why would the 40deg frequency not cause more ringing? Right: If you set the amplifier's closed loop gain to that gain < GBW where you find this 40° PM dip, the amplifier will show more ringing around that frequency. [QUOTE=dia
How would u mathematically prove that CE amplifier has 180 phase shift
Hello all, I am designing a differential amplifier. I have read definitions about gain, gain bandwidth, slew rate, ICMR, OCMR and phase Margin, but which value of these specifications are desired for a common differential amplifier? (For example: gain should be 60dB or 80 dB?) Thanks for any help in advance.
An oscillator needs positive feedback. If it has only negative feedback then it is an amplifier, not an oscillator. The phase shift circuit in an oscillator has a certain amount of signal loss which must be made up by the gain of the circuit. A simulator does not know that noise is amplified and gets an oscillator to start oscillating. Then you mu
Probaly normal behaviour. Transimpedance amplifier is inverting, thus 180° phase shift observed. phase decreases according to the poles in frequency characteristic.
if it were me, i would start off with a 10 GHz DRO running CW, add a 10 dB pad at the output, then add a 10 dB gain amplifier, then add a spst non-reflective 50 dB isolation switch. You should be able to run that at KHz switching rates without too much frequency movement. BTW, it does not matter if it is phase locked or not, you will see an ins
hi, One option is to use a OPA amplifier for the 100mV sinusoid. What amplification do you require.? E
This is Output Impedance of the amplifier and it should be matched to 50 Ohm to get the Delivered Maximum Power.Nevertheless it doesn't impact the modulation scheme but delivered power is droped if matching is not done.
Hello, I have the following circuit testbench which i presume it's wrong since i have problems plotting the gm. I do in calculator deriv("current IS in the node of the gnd" ; tried also with a resistor, and still no luck). and I sweep the dc voltage of V4. Could you please help me? Thank you 108046
An amplifier has transistors that have some capacitance and wiring also has some capacitance. The capacitance causes a phase shift at high frequencies. An amplifier usually has negative feedback to reduce its very high gain to a useable amount and to reduce its distortion. The phase shift at a high frequency causes the (...)
Hi every one I want to measure DC offset of a differential amplifier in cadence spectre and untill now i understood i should use monte carlo to simulate but I have no idea how i can use it and how to measure dc offset. could you please help me? best regards matin
The term "lock-in amplifier" doesn't exactly match the application, but a complex impedance measurement with phase sensistive rectifier is perfectly suited. In addition a measurement circuit that is insensitive to cable capacitances, e.g. voltage source/current sense. That's how all AC impedance (LCR) meters work.
The transistor is a "common-base" amplifier. Its collector feeds positive feedback to its emitter through C2. Some websites call the oscillator a "Colpitts" type.
Hello everyone. I have been given a task to design 'quadrature phase detection module' for an RF Receiver but i am unable to understand its need and function. The one i have been asked to design gets two IF signals at its input (sum and difference IF signals). After passing through amplifier and band pass filter each, they are given to the i
When You designing two stage ota, the first of all You need to add a compensation network (e.g. Miller cap with nulling resistor or used a cascode compensation). Your amplifier is unbalanced - output transistor should be matched with first stage current mirror load. In addition the phase margin and GBW depends to feedback type, reference voltage,
I am not sure if this answers your question: Sinusoidal signals can be expressed by exponenetial functions like Vin=Vo*exp. If such a signal is applied to a frequency-dependent network (filter, amplifier) the output will change in magnitude and phase like Vout=A*Vo*exp. Thus, the gain is Vout/Vin=A*exp.
If you are not using the amplifier in a radar design, is not worth to bother about its phase noise, because there are many other parameters that breaks before failing the system phase noise.
Hi all, We have designed an RF front end receiver (Low Noise amplifier and Passive Mixer)....Right now we r doing PSS, PAC, PNOISE analyses..... 1. Can we plot Conversion Gain Vs input RF frequency...? 2. Can we plot Noise Figure Vs input RF frequency..? Please give me valuable suggestions how to do those analyses......?
I agree with johnjoe, "source unleveled" is also a possible warning in case of oscillating amplifier.
phase shift circuit when output phase is 180 degree has gain 1/29. Conditions for oscillating are satisfied when amplifier gain is 29 minimum. Gain we are talking depends on type of phase shift circuit.
Hi, I am working on the design of Instrumentation amplifier for ECG system. Initially, I designed a Difference differential amplifier. When I checked the Gain and phase margin response, the system is highly unstable. I observed phase margin in negative value and 3dB cut off frequency at ten's of MHz. I tried to add a (...)
I thought that I already explained the problem in post #2. The circuit obviously isn't stable in large signal behaviour. Once you manage to excitate a sufficient large deviation from steady state, the error amplifier exceeds it's linear range and the circuit falls into a kind of relaxation oscillations. The initial startup has different initial
Hi guys I have to design an amplifier with the following conditions. Since i am new in this, I need some help. Can you guide me on how to start on this? Supply voltage = ?0.9V (Fixed) Load condition = 10pF (Fixed) Low-frequency gain ≥ 80dB Unity-gain frequency ≥ 5MHz Power consumption < 500uW phase at unity-gain frequency 
Noise figure is such an innacurate term. It is if someone asked what your girlfriend looked like, and you said "she is generally nice". The asker would still be wondering. Figure out the residual AM and PM that is needed in the amplifier, and go try to find that. Maybe you can tolerate close-in or far-out noise, for instance
and another from referance to "+" terminal Why? Sounds definitely wrong. Generally speaking, you would to test the current sense operation under well defined conditions first. ("calibrate" the sense amplifier) - no output without a load - correct output with defined resistive load - correct output with defined capacitive load