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Questions tagged [power-amplifier]

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0
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1answer
90 views

Isolated High Voltage Amplifier Idea

Test laboratory of our factory asked me to design an isolated high voltage amplifier. Here are the requirements: The circuit will be built with transistors and passive components in the lab. (No IC ...
1
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1answer
73 views

How do I choose the power rating of resistors in audio power amplifier?

I read a bit about audio power amplifiers and struggle to understand the power rating of the emitter (i.e. current sharing) resistors in power amplifiers. I refer to this project. [EDIT: schematics ...
1
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2answers
60 views

Why should the bias servo transistor not be placed on the main heat sink for a Sziklai pair?

The Wikipedia page on Sziklai pairs contains the following statement (emphasis mine) Sziklai pairs can also have the benefit of superior thermal stability. [...]. [Q]uiescent current is much more ...
1
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1answer
42 views

Power amplifier shows 0 input and output resistance

I have a non-functioning transmitter for a radar I've built. When I was checking for shorts using a multimeter, I noticed that the resistance measurements between RFin and GND and RFout and GND of my ...
0
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1answer
57 views

alternative amplifier for vibration exciter (shaker)

I am using a second-hand LDS V201 permanent magnet shaker, and would like to use this to test and validate some monitoring equipment. I would like to generate signals suchs as sweep sines, but these ...
0
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1answer
28 views

Calculate input resistance of power amplifier

how can I calculate the input resistance of this circuit? Thank you!
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0answers
46 views

Amplifying pulse signals causing pulse lengthening problems

I am currently trying to design a circuit that would sense a voltage change at its input, convert that change into rapid "on"/"off" change at output and amplify same switching voltage to high current (...
0
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2answers
136 views

Power Amplifier (Darlington) with Power and current limitation

I'm designing a power amplifier and the following circuit is the output stage. My output stage consists of two complementary transistors for both, positive and negative waves but for better ...
0
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3answers
128 views

Power amplifier, does this circuit work?

I found that circuit for a power amplifier. Does it work? I want to build one for myself.
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0answers
47 views

Built-in power amplifier of the ST7580

The ST7580 is a power line communication device that can be controlled with any host controller. The ST7580 has a buil in power amplifier to allow it to send a modulated signal (0Hz to 250kHz) as far ...
2
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2answers
166 views

What's wrong with my1943/5200 Mosfet Amplifier? Blown on first run

I have just brought an 1943/5200 mosfet based amplifier board. Shopkeeper said it's rated for 24-0-24 AC. So I connected it with 24-0-24 transformer like this in image below. As soon as I turned the ...
2
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2answers
61 views

Question about the power rating of a RF power amplifier

In HMC453ST89's datasheet, it gives the electrical specifications when Vs = +5V: The max. output power is around 32.5dBm, about 1.6W. But for a 50 Ohm load, 1.6W means the peak voltage is about 12V. ...
0
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1answer
65 views

How close to P1dB can I go?

I'm trying to decide on a safe input power to a power amplifier. The amplifier in question is SE5004L. The datasheet specifies that the amplifier output 1-dB compression point has a minimum value of ...
-2
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2answers
86 views

Stk086 distance between pins? [closed]

I have been trying to make a footprint for this IC, and trying to figure out the distance between pins, it is a 10 pin ic what do you think the distance will be? What is the normal distance between ...
1
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1answer
210 views

IR2110 driver output causing shoothrough despite deadtime

I'm having trouble with the ir2110 output. I'm working on a class d full bridge amplifier and I use 2 ir2110 to drive 4 irf540N mosfets. The switching frequency I use to generate the PWM is 240kHz and ...
0
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2answers
107 views

How to design and build RF amplifier, that work in 450Khz [closed]

I have a schematic, that is a sine generator and mixer that does AM modulation. How to design and build an RF power amplifier and build a compact antenna. The goal is to transmit signal up to 50 ...
0
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2answers
63 views

Maximum output power of a PA

I was discussing with a friend about maximum output power of a (class A/B power) amplifier (for example if the device following the PA can only tolerate a certain amount of power). If the input power ...
1
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2answers
429 views

Biasing Class AB power amplifier with MOSFETs

I am having trouble getting the resistor biasing to meet a minimum 1.25W at the output: Note, the distortion and watt meter. I was told the SPICE parameters for the FETs didn't really matter. (...
0
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2answers
48 views

Understanding of class-AB currents

I am trying to understand a simple class-AB output stage. The bias voltage for the transistors is made by using two diodes. The following picture show the circuits. The currents drawn are how, i ...
0
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2answers
164 views

Design a tank circuit for class C power amplifier using ADS

I am trying to figure out the best values for the tank circuit values (L and C) in order to compare the amplifier's efficiency with the output power I have chosen the tank value L1 and C7 to resonate ...
0
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1answer
32 views

Vibe Table: Increase Peak Force Output?

I'm driving a small, benchtop vibe table (shaker) with two Crown DSI-1000 PA's, and also cleaning my signal with a DBX 231s EQ. Currently running the system at 6.8 GRMS, but I'm looking to increase my ...
2
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0answers
284 views

TDA7294 100W Audio Amplifier Causing Unexpected Problems

This is the circuit I will be referring in this question: TDA7294 is described in this data sheet. Upper IC with added external components is a well-known circuit and can be found on many websites ...
1
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1answer
85 views

RF power amplifiers and preventing damage when the antenna is disconnected

I'm looking at Wi-Fi 2.4 GHz power amplifiers and I can't find a single high power (500 mW) one including a system protecting it from damage. I can, for example, find some ~ GHz PA with protection ...
0
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1answer
39 views

AWR PA Output Power Simulation - Credible?

I'm working with the SKY65111-348LF power amplifier from Skyworks and wanted to obtain some idea of its performance using AWR Microwave Office. I'm not sure if my process is correct and wanted to have ...
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0answers
318 views

Increase output power of simple class AB audio amplifier

How could one increase the output power from a class AB amplifier circuit like this one? I wish to increase the output power to around 2W. The above picture is simulated with a 200mV amplitude, 5kHz ...
0
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2answers
59 views

Conventional current in a power amplifier?

I recently learned that electricity doesn't actually flow from + to - but the other way around.. So my question would be: if I was using a 2 channel power amp and connected a speaker to it with the ...
2
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2answers
127 views

Resistor network in between SAW Filter and Power Amplifier

I am going through user guide of Microchip's LoRaWan Gateway. The manual is over here. At page 48, I am struck at one resistor network and unable to understand it's ...
2
votes
2answers
114 views

Can someone help me with this power amplifier problem?

Wire the circuit shown:

 R1 = 68KΩ R2 = 10KΩ R3 = 10KΩ R4 = 200Ω ( two 100Ω in series ) R5 = 2.2kΩ C1 = 0.1 µF C2 = 0.1 µF Q1 = 2N3904 
 Set the sig. Gen to 50mv RMS.  With frequency ...
0
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3answers
228 views

15-20W amplifier circuit

I'm trying to build a small radio amplifier which will deliver around 15V at 1A at 250kHz from a 0.2V input of the same frequency. I have searched for and tried as many online circuits as I can which ...
6
votes
4answers
908 views

BJT base connected to ground and still operates?

When in university I used to get confused how a transistor (NPN) can draw current from ground. I'm now studying power amplifiers and again, this same configuration appears. How does Ir draw current ...
1
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1answer
450 views

Calculate the total max power dissipation in CLASS AB push pull for reactive loads

As worst case we can assume in reactive load the same power dissipation with the resistive part of that load. Thus for a 8 ohm impedance with phase angle of 60°, we can use \$R_L=0.5*R_{Reactive}=4\...
0
votes
1answer
46 views

Using an RF adapter to improve LTE signal in the house

In my apartment, the GSM signal is very scarce, if not absent at all, except for a few spots, where there's a decent LTE signal and I can browse internet reliably. In order to improve the reception ...
-1
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0answers
179 views

Equivalent load resistance, AC and DC load lines for push-pull class A amplifier

I have a question which is about a class A push-pull amplifier as shown below, but I am not sure with my ideas: I could find Icmax and Icmin in part a), which are 240mA and 80mA respectively. As ...
1
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2answers
275 views

Class A power amplifier: power dissipation

Let's consider the following class A power amplifier: And here is the time-domain simulation of the power dissipated across the transistor: As we can see, the power varies from approx \$0.1W\$ to \$...
4
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2answers
1k views

Confusion between Class B and Class AB Amplifier

I am reading about output stages of an amplifier and classes of amplifier. The following circuit is named as "Class B" amplifier. From my understanding, the above circuit should be a class AB ...
1
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1answer
213 views

What do the inductors L2 and L3 do in the following rf power amplifier circuit?

I found a circuit online about an rf power amplifier working in the 88 to 108MHz FM spectrum. The circuit diagram is shown below I understand that an amplifier needs an inductor and a capacitor in a ...
0
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0answers
58 views

Power amplifier design using microstrip or CPWG in Keysight ADS Schematic?

There is alaways a question which confused me when I started the design of a power amplifier : Which type of trace do I need to choose for design in ADS shcematic ? Microstrip or CPWG ? I read some ...
0
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2answers
247 views

Push-pull amp in class A what it mean

I take next sample schematic. This is only an output stage of any real power amplifier. It's clear when it's work in B-class the every BJT amplify only one half of input signal. But what it means if ...
1
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1answer
152 views

Two diodes in input stage of power amplifier

Some of the power amplifier schematics include diodes in input stage like below. What is the purpose of them?
0
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0answers
42 views

Difference between two equal valve tubes

Is there any difference in "Plate Voltage"/"Plate Current" curve between two real vacuum tubes 12ax7?
0
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1answer
336 views

Impedance of an Electret Mic

I have an electret mic for the design of an audio amplifier using input and output stages. How can I measure the impedance of that mic?
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3answers
97 views

class AB amplfier help

as a class project, we were given a circuit schematics of a low distortion audio power amplifier. and we were asked to simulate it, i did that no problem. however I am trying to understand the circuit ...
0
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1answer
326 views

How RF Choke doubles Vcc at collector in BJT Power Amplifier

I'm trying to analyze a class A RF power amplifier as represented in the picture. The main thing I'm trying to understand is how the collector voltage can go to 2x Vcc as according to this page. ...
-1
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1answer
52 views

Power Amplifier inside an OPAMP

Here is a simplified schematic diagram of one of the operational amplifiers inside a TL08x. The Diagram I wonder why a power amplifier is used ? (on the right side) What is it good for ? Thanks in ...
3
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3answers
513 views

Audio power amplifier features identification

There is the power amplifier circuit here: How 18k/1k/.0012uF filter works in the input circuit? It's clear for me that Q1/Q2 is a transconductance stage: voltage in - current out. But where is that "...
0
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3answers
147 views

Differential stage Av value with current sources

Why all books told that Av differential of an differential input stage in power amp is very big? Ad = Rc/re, but if there are current sources in the emitter and collector circuit they will have too ...
-3
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2answers
114 views

Power amp Av with current source

How could I calculate the voltage gain Av for the following power amplifier diagram? Here there is an example how to find it but the schematic doesn't use current sources and use the voltage drop on ...
0
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2answers
170 views

Power amp current source reserve requirements

If I use current sources in power amplifier need I make it current value 5 or more times greater than the next stage may consume? For example if I drive 6 amp current though load I may found that 6/(...
1
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1answer
168 views

Audio power amp oscillogram gap

I'm trying to debug that circuit (pic. 2). The problem is when the input signal is near 2V the output oscilogram looks like in pic. 3 (with gap). What is the nature of that gap? Looks like some of ...
0
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1answer
307 views

How to measure the RF output power of the PCB board?

I have designed a PCB board, having a RF power amplifier with an output power of 34dBm and two voltage regulators giving output voltage of 2.7V and 3.5V respectively which will be the input to power ...