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Questions tagged [amplifier]

An amplifier can be used to adapt the range of the signal to a requirement, to make it more robust for transmission, or to satisfy interface requirement (like input/output impedance)

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66 views

Commercial broadband RF amplifiers

In the process of designing a broadband RF amplifier, I've come across some commercial boards, claiming gain flatnesses of +-1db from DC to 1Ghz. Those boards are ridiculously simple, having only one ...
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2answers
92 views

Extension of Audio Amplifier's Bandwidth

I am curious, whether extending audio amplifier's BW (bandwidth) beyond 20 kHz has any benefits compared to 2Hz-20kHz audio BW amplifier? Some say that high-frequency -3dB point should should be ...
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2answers
78 views

What is the purpose of \$C_E\$ in this circuit?

I understand it acts like a filter for \$R_E\$, but what is the point?
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71 views

Identifying Noise in 12AU7 Based Headphone Amplifier

I've been working on making a tube based headphone amplifier as a fun personal project. The amplifier is based around this 12AU7 vacuum tube. The project for the most part is following this existing ...
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4answers
622 views

High resolution ADC vs amplifiers

I have started a design for work where I want to interface some sensors, (strain gauge, bridge, thermocouple, low voltage stuff) to a national instruments sbRIO card. This card has analog inputs built ...
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1answer
48 views

Voltage drift in lock in amplifier

I am testing out the lock in amplifier with just a single resistor, but there seems to be a downward drift in the in phase voltage. What could possibly cause this to happen? Could it be some grounding ...
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1answer
46 views

Measurement isolated loop with Op Amp

I'm trying to measure a voltage across an Rsense (R2) in a galvanic isolated loop that flows a current (4 - 20mA). My Op Amp has Vcm +20V. But I'm worried about the voltage in nodes B and A with ...
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1answer
178 views

Reducing effect of MOSFET parasitic capacitance with resistor in series with gate

I have a MOSFET in series with the output of my amplifier to switch the amplifier output to the downstream circuitry. The MOSFET parasitic capacitance is seen as a load capacitance by my amplifier, ...
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2answers
201 views

Common emitter amplifier gain with load resistor?

I have a problem I am working on where I have to find the voltage gain of the following circuit with a dc collector current of 0.3mA. My attempt at a solution involved using the formula A=-(RcIc)/Vt ...
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1answer
86 views

Calculating grounded emitter amplifer distortion (Art of Electronics 3rd Ed.)

Referring to section 2.3.4 A1 (pages 94-95) of the Art of Electronics 3rd Ed., I'm having difficulty understanding how to calculate distortion of a grounded emitter amplifier. The book says: ...
3
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1answer
724 views

How to determine op-amp gain with active feedback?

The Howland current pump uses an op-amp in the configuration below with a resistive feedback network which gives me the gain show below: But if I decide to swap the feedback resistor for an ...
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1answer
90 views

Power Dissipation of Op-Amp

If we look at the output stage of the MP111 op-amp it's just 2 MOSFETs in series. I'm curious why the power dissipation of the device isn't simply \$R_{\text{ds(on)}} \times I_{\text{out}}\$, but ...
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0answers
60 views

Confirm re model of transformer coupled BJT amplifier

Could someone confirm my conversion of this transformer coupled BJT amplifier into a \$r_e\$ model? simulate this circuit – Schematic created using CircuitLab I get \$I_E\$ = 3.11mA and \$r_e\$...
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2answers
78 views

Best Guesstimate for Capacitor Replacement [closed]

I'm repairing an old (circa 1960) console hifi system for my parents. I'm no expert but also not totally incompetent. It originally came from Sears, I do not know the model number, nor the power ...
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2answers
119 views

How can I calculate V1 and V2 in this circuit?

How can I calculate V1 and V2 in this circuit? This is what I tried so far: Calculate the voltage of R5 through voltage divider but I didn't find the way, I was looking about second OA circuit but ...
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2answers
64 views

Amplifier Output Clipping

When an amplifier output clips at a certain voltage, does that mean the maximum voltage that its output can provide is the voltage value where the clipping occurs?
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1answer
44 views

NMOS/PMOS Characterization

I have some questions regarding NMOS/PMOS characterization. I'm designing a common source amplifier using gm/Id method and since it requires characterization, I did so but using minimum lengths and ...
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1answer
39 views

4.5µA Li-Ion Battery Protection Circuit

I tried to simulate the circuit given in your design note "https://www.analog.com/en/technical-articles/battery-protection-circuit.html" According to the designer, the cut off voltage is 3V but the ...
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1answer
62 views

Q: LM833N acting weird above 9V

I have a quick question as to why my LM833N is behaving as such. Any time I try to power the amplifer with 9V or over nothing happens, its just a flat line on its output like its turned off or ...
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1answer
51 views

Confusion with a simple two stage amplifier design example

I have been following a lecture on net about a two stage amplifier example. It is basically a BJT amplifier with a PNP emitter follower as shown below. I named some of the nodes for clarity: The ...
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1answer
141 views

Can't find source of hum in left channel of bluetooth speaker that I built

I have an RN-52 bluetooth audio module - https://cdn.sparkfun.com/datasheets/Wireless/Bluetooth/rn-52-ds-1.1r.pdf I am using it with this amplifier - https://images-na.ssl-images-amazon.com/images/I/...
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2answers
39 views

Calculate linear phase when given in decibel

The datasheet of the LT6230 shows the opamps phase lag in decibels (page 14). The datasheet does not give a formula to recalculate the angle in degrees, so can I just assume the following being the ...
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1answer
42 views

using TTL to drive LED

I have a TTL signal of 1 V, and I need to drive an LED by amplifying the TTL to 3 V. I used the following voltage amplifier circuit with Rc = 10 KOhm and Re = 1 kOhm. The DC input I use is 3 V. ...
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1answer
38 views

Hall sensor for slowly varying magnetic fields

I am trying to measure the change in the field of a permanent magnet (at about 50 mT) due to temperature fluctuations at room temperature (timescale ~ mins to hours). The sensor I am currently using ...
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1answer
56 views

Mos amplifier numerical

Can anyone please explain how do I get this variation of Ix vs Vx curve?How do I determine whether the current will be in positive region or negetive?
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1answer
43 views

Mos amplifier output characteristics

I have a problem in the first region where M1 and M2 are in saturation.If both the NMOS are in saturation,how can the Vout be VDD.Shouldn't Vout be close to 0V as the pulldown current is much greater ...
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2answers
48 views

Mos amplifier region of operation

In the solution presented I have doubt regarding the 3rd region where both Mos are in saturation.When M2 shifts from triode to saturation how can we say that that the Vout will still be increasing?Isn'...
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1answer
25 views

Adafruit audio FX mini and 2.5W amplifier

I am connecting Adafruit's Audio FX Mini board to a small Adafruit's amplifier. In order to save some power when the sound board is not outputting any sound, I wanted to connect ACT pin of the sound ...
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2answers
58 views

SPICE circuit to find AOL and noise gain of Transimpedance amplifier

In Chapter 10 of Art Kay's book "Operational Amplifier Noise", he gives a SPICE circuit (pp.179) that can be used to generate the noise gain, AOL, and current-to-voltage gain. Could anyone explain to ...
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1answer
75 views

What are these inputs for this audio power amplifier?

I have made a preamplifier with filter but before asking that question I decided to open a specific question about a MOSFET audio power amplifier. It seems an old one and I cannot find its data-sheet ...
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0answers
68 views

Using a single channel on a 2 channel DAC + Amplifier

I am planning to use an external DAC + amplifier combo to output mono sound from my microcontoller. The ouput from the amplifier would be connected to a single speaker ...
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3answers
85 views

What could be a near rail-to-rail opamp with very low voltage for this use?

What could be a near rail-to-rail opamp with very low voltage for this use? LM386 seems to be out of limits for my needs. How do I choose it from datasheets? What values are important (of course ...
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2answers
177 views

How to design a circuit starting from a block diagram?

I am struggling with the following self-study problem, taken from The Analysis and Design of Linear Circuits (8th edition). There are two things that shock me from this problem. We need to get a ...
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1answer
235 views

Reasons for choosing a transistor instead of an op-amp as a buffer

I have often seen circuits for guitar pedals that use an emitter-follower configuration as the input and output buffer (see example below). If an op-amp can provide a greater input impedance / lower ...
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3answers
129 views

Differential to single ended audio signal

I'm working on an interface that will be connected instead of a speaker, input of my interface is differential, and output is single ended. I'm using the following schematics : R3 is the load to ...
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2answers
55 views

Why does these capacitances have no effect on the output of this amplifier?

Below shows a piezoelectric sensor connected to a charge amplifier: The text claims that the output voltage Uout is to a good approximation only charge q which is going to be measured divided by the ...
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2answers
55 views

How do i drop voltage in series?

I have a 12v PSU output voltage that uses around 9A, i need to decrease this voltage to 11v but keep the amperage the same, any ideas? thanks
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1answer
31 views

What happens when the DC supply of this common gate amplifier is switched off?

The Vin in this case is a 200mV peak to peak sine wave signal. what happens to the gain of the amplifier when the DC supply of 10V is switched off?
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1answer
61 views

PWM Comparator types for Class D

I've started simulating a Class D amp, but it seems the MAX999 (I saw recommended elsewhere on this site) isn't working. Could anyone point me in the direction of why? I swapped in an LM311 which ...
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1answer
114 views

Designing two stage CE amplifier with negative feedback [closed]

I'm trying to design two stage ce amplifier with negative feedback using 2n2222 transistors. The circuit must have certain voltage gain, Rin, Rout, Vcc, low and high frequency filter. This is the ...
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1answer
65 views

Circuit Design for ECG amplification

I've come across this circuit diagram in Biomedical Digital Signal Processing by Willis J Tompkins and in the description it says it is to do with ECG amplification. The input to the non-inverting ...
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3answers
394 views

Understanding Operational Transconductance Amplifiers

I understand the high-level function of OTAs, that they provide an output current proportional to an input voltage. But what I don't understand, and what I can't seem to find any information on online,...
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3answers
185 views

Inverting OpAmp with voltage divider in feedback loop

Last week I was looking for a programmable gain amplifier (PGA) with high gains (> 100V/V) and low noise. As far as I know most of the PGA integrated circuits out there are just (inverting) amplifier ...
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1answer
69 views

Amplifying milli Volts to Volts

I am currently using a KE-25 oxygen sensor which is galvano microcell type oxygen sensor which doesn't require a power supply to sense oxygen level in the environment. Depending on the concentration ...
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2answers
123 views

Will this receiver work?

I'm just a beginner, trying to understand an antennas and transistors as an amplifier, I'm studying, please correct me. Here we have a voltage source, PNP bipolar transistor emitter-base-collector ...
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1answer
30 views

I need to find Vin max(Common Mode) and min(common mode) for given circuit.

please let me know how i can proceed with this circuit
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2answers
74 views

Why voltage source has been connected via inductor at the output of LNA?

I have been reviewing the schematics of LoRaWAN Gateway designed by Microchip (Page 48). The output of the LNA has been connected to voltage source via inductor. ...
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3answers
111 views

Amplifying a pulsed current

I need to pulse a current through a coil, to create relatively short magnetic pulses. I would like to know if I can use a function generator as the source of the pulses and amplify the current that ...
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1answer
266 views

Is there any difference between AD620 vs INA128?

I'm trying to make an EMG sensor. I've found some tutorials, for example, DIY muscle sensor/EMG circuit for a microcontroller, but my main question is can I make an EMG sensor using AD620 instead of ...
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1answer
72 views

Need help extracting line out signal from car radio

I'm trying to extract audio signal from my car stereo and use it as an input to my external amp. The place I want to get it from is marked in red in this picture: I used the IC31-34 pin12 to get the ...