Questions tagged [amplifier]
An amplifier can be used to adapt the range of a signal to a requirement, to make it more robust for transmission, or to satisfy interface requirements (like input/output impedance).
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Why does this transistor amplifier fail if Rc is greater than 50 ohms?
This simple circuit amplifies a 1 µV 50 ohm 7 MHz signal (e.g. RF off an antenna) quite nicely (31 dB):
However, I'm stumped as to why R2 must be so low (50 ohms), giving a Ic of close to 50 mA. ...
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Why do direct conversion receivers amplify only after mixing?
The vast majority of the simple direct conversion receivers I've seen amplify only after mixing. The RF is filtered before mixing, but not amplified at all. For example (from Solid State Design for ...
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Determining the zeros and poles of a common emitter amplifier
I want to determine the transfer function of the base common emitter amplifier. I don't want to neglect the impedances of the capacitors in the calculations because I want to determine the zeros and ...
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Decent MOSFET for a beginner to learn from?
I am relearning MOSFETs, but more importantly I would like to focus on building some basic circuits and learning practicality over theory. I have a BSEE but haven't spent much time outside of class on ...
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Applying KVL in op amp with floating source
From my understanding, the solution first applies the summing point constraint even though there is no ground on the non-inverting input, leading to 0V on both inputs. But how do they apply KVL across ...
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Is it correct to apply KVL through the 2 inputs of an op amp?
The question asks; "P14.25 Analyze each of the ideal-op-amp circuits shown in Figure P14.25 to find expressions for 𝑖𝑜. The top part is the question, the bottom is the solution from the ...
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Working of differential pair using MOSFETs
I am currently learning about differential pair using MOSFET from this course. In this particular lecture, the teacher says that to have a differential pair we need to apply the second signal v2 at ...
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Why does a MOSFET fail on fast signals, even if they're much longer than the turn on + turn off times?
When running at a fast signal, why does the MOSFET below not turn off, even when gate voltage is well below threshold (even negative)? Although the signal is fast (7 MHz, 140 ns period) it is < 1/...
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Impedance matching T/R switch
I do drive a piezo as transceiver. My transmitter provides square burst around 10Vpp which is too big for simply switching through a diode by dc biasing. I found out that bridge rectifier structure ...
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Please help me identify this IC - top marking "CEK"?
Please help me identify this IC - top marking "CEK" such as picture below:
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Regarding the voltage in the resonant circuit of a Class F amplifier
When checking the operation, the secondary resonant circuit discharges.
When I checked with ADS, I confirmed that the voltage was not high enough to cause a discharge at 150V or less.
Regarding the ...
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Why input signal of negative feedback amplifier is Vs - Vf?
The block diagram below is from my textbook. I don't understand why the input voltage Vi = Vs - Vf. Take an example as the image with numbers on it, I know its not correct in reality but just assume ...
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How would one calculate the transconductance of the FETs in this circuit?
I was given formulas to find the transconductance (gm) of the FETs using IDSS, VP and VGS, however, none of the ways I tried them leads to the correct answer (given as 2,55mS).
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Please explain the purpose of R3 and R4 in this ground isolating amplifier
This schematic can be found here on page 15:
Here's what I do understand (I think):
The ground noise is common mode voltage, and the amplifier has high CMRR, so it gets rid of the ground noise at G2
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50 Hz 2.5 Vpk-pk signal amplification [closed]
I get a 49.8 Hz 2.5 Vpk-pk sine signal. I want to amplify this signal and drive a 22 Ω resistor. Do you have a chance to provide an example of amplifier circuit design? As a result of this upgrade, ...
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