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Switch Power Amplifier

70 Threads found on edaboard.com: Switch Power Amplifier

What is the output impedance of a square wave switch-mode RF "amplifier"?

135920 I am trying to get an idea of what the output impedance of this circuit would be. First off, the harmonic termination is terminated with a 50 Ohm resistor (Rh) Lh and Ch are parallel resonant at the output frequency. LPF Characteristic impedance would be 50 ohms. My theory is that Rh would dominate as the i

Mixer large bandwidth or RF Switch ?

Hello, I am looking for a discrete device for this function. I would call it a mixer with large bandwidth DC-9 GHz but it does not exist. I think about a RF switch, but it is complicate to inverse the input signal. In a paper I read, it is called Code modulating LNA, where the Vdd can be positive or negative. Do you have any ideal about

Which BJTs/ FETs to use for trying out basic circuits

An IRF640 is Quite Common. But it would be better if you stated the Purpose. PWM Circuit, power amplifier, switch mode Circuit, ETC. Also How Many Amps and What Voltage.

class E power amplifier fabrication problem

I think is not justified to design a high-efficiency Class-E power amplifier at +20dBm, because at this relative low output power the transistor cannot behave as a perfect switch, as the Class-E requires. Especially when use a transistor that was designed and manufactured as an LNA, which theoretically should work in pure (...)

TL431/Opto error amplifier transfer function is incorrect? (feedback in SMPS)

Do you agree that equation 35 of page 10 of AN-4137 is incorrect? AN-4137: It surely should say? VFB/Vo1 = - (wi/s) . Do you agree? This is confirmed by equation 3-58 of page 290 of Basso?s book ?switch mode power supplies? (attached)

power switch on the volume control

the AC switch on the back of the pot would not meet today's safety standards....!

Differential amp to measure 0-30V DC in power supply

Hi I need to measure DC voltage 0-30V on a microcontroller and display the same. Since we need to measure a large voltage I made a differential amplifier to measure input voltage and added a NFET switched voltage divider at input to measure higher voltages. the switch will be off at lower voltage to get better resolution. 122015[/A

DC power through audio socket acting as amplifier 'power-on' switch via jack sleeve.

I am building a compact 2W stereo amplifier to work primarily with a smartphone audio output. To keep components to a minimum I have elected to have the unit power up only if there is a jack in the unit?s audio in socket. This is done by routing the 0 volts line from the battery to the amp via the sleeve connections on the jack socket ? i.e. via th

Negative voltage for drain in class-E power amplifiers

Friends, I would like to design a class E power amplifier. As you know, voltage and current waves of the switch in negative peak must be zero, but in my circuit they have negative values. When voltage is negative, current is positive!So, in this condition the switch can work as a source of power and can (...)

SG3525 push pull converter issues.

It is not a good idea to test the switch mode power supplies on bread board, unless you are expert in power electronics. High frequency switching currents creates lot of noise and spikes in ground. PCB with good layout is recommended.

HT12 Encoder and decoder question

Why did you mention a microphone and a speaker? A microphone will not press a pushbutton switch on the encoder and the decoder does not have a power audio amplifier. If you set the encoder's oscillator to be an audio frequency then there will simply be a buzz if the decoder has an audio amplifier and speaker connected. I (...)

Transceiver TRX switching, how is it done?

When you tie the switch to gnd, Q2 turns off, Q3 turns on and buffer amplifier is supplied through this transistor.

[Moved] Analog Power Amplifier - OPA549 Shuts Down Unexpectedly!

You could avoid the any momentary dropout during voltage switching if you connect the +12V bus to the amplifier through a Schottky diode (for minimum voltage drop). Then when you switch in the +24V bus the voltage will simply rise from 12V to 24V with no transient, with the diode isolating the +12V bus.

Using optimization tools to optimize Drain Efficiency in a Class-E power amplifier

Dear friends, How can I use optimization tools in ADS to optimize drain efficiency of my class-E power amplifier? As you know, to gain a 100% efficiency (theoretically) voltage of switch and derivative of switch voltage at the time when the switch wants to be on should be zero: v_s (2π)=0 (dv_s (...)

Need a bit of help with a 12V 10A SMPS design using TL494

Can I use the Vref (instead of dividing it) as one of the references for the error amplifier and then divide the 12V to 5V as the other reference for the error amplifier. Yes. Second: The power switch seems to be a pair of NPN=PNP transistors. Can anyone recommend alternate parts for these? The NTE153 and NTE331 are not av

Switching MOSFET with Hall Effect Switch in battery powered device

transistor or FET or MOSFET in common-emitter mode between the switch and power MOSFT

Transfer equation for optocoupler feedback in SMPS when R(LED) not connected to Vout?

Hello, Equn 3-58 on pg 290 of Basso's book (switch mode power supplies), gives the error amplifier transfer function for the case of R(LED) being connected to vout of the SMPS.....However, what is the error amplifier transfer function when the R(LED) is connected to a regulated and fixed bias voltage ? (ie as in fig 3-41 (...)

PA enable control in wireless power amplifier

You should do these things properly and respectively to turn off the PA while the Load is still connected. -switch off the input signal -Turn off the main bias -Turn off the gate/base bias

mm-Wave Cascode Power Amplfier Biasing

Unless you are not going to put the cascode PA working in E Class or something similar (switch operation) your circuit would have less PAE than any other single transistor amplifier. For maximum PAE is not enough providing the right bias to the amplifier, but also the amplifier must get proper load resistance, which cascode (...)

Class E power amplifier

You need to understand how a class E amp works. Basically, the MOSFET is either fully on or fully off-it's working as a switch. I'm not an expert on Class E amps, but I believe they are only used for RF, but you're talking about increasing DC current; I'm not sure I understand. Do you just mean the ON current of the device? As I said before, the

laser diver circuit whch drive the 250ma and 3 v

an current source or switch can be better controlled. You may checkout the iC-HK - it works with 3.5-5V supply and up to 300mA with two channels. Enjoy your design work!

LMP7721 fA bias current used as electrometer

The circuit can only work if the switch has similar low leakage as the amplifier. Did you identify a suitable transistor?

Class B and Class AB amplifier dissipation when no signal?

A linear class-AB amplifier gets hot when it is driving power into a speaker because it is a variable power resistor between the power supply and the speaker. The output Mosfets in a class-D amplifier switch completely on (no voltage aross them so they do not get hot) and (...)

Microwave amplifier Design

Using s-parameters is useless in designing "switch mode amplifiers" because they are not valid anymore in this mode. E-class or F-class amplifiers are desgined by using nonlinear models and HB simulation technique. Grebennikov's "High Efficiency power Amplifer Design" book will help you and some other papers of IEEE on this (...)

What are the range of temperature change caused by switching on/off power amplifier?

I am having a bluetooth and an FM radio on the same 65nm die, but it seems ther FM loses channel whenever the bluetooth power amplifier is switched on.. What kind of temperature change can one expect from the switch on of PA? Is that kind of temperature change well known or design dependent?

Using an amplifier bidirectionally

You'll typically need an external Rx/Tx switch (e.g. GaAs device from Hittite or RFMD) when adding a PA or LNA to a transceiver chip. Possible solutions are often discussed in application notes of transceiver manufacturers.

Home made tube amplifier SE EL34

Presented here amplifier is a typial Single Ended based on EL34 in the power stage operating in triode and pentode mode (selected by a switch) and ECC82 in the preamplifier operating as White follower, EM84 as a meter and EAA91 as

Power amplifier for DC motor?

I like the Electronic resource book sky_123 for ease of reference. I'm not sure what radagast had in mind for biasing the mic DC voltage and what voltage the motors are rated for. 6V may work if that is what he has intended. with 4 AA cells. THere are two possibilities. VOX toggle switch with constant Voltage (CV) or Voice controlled torque.

5.9GHz Front-end board - PCB material

Hi to all, I am new by here. I am going to develop a board for WLAN 802.11p communications. In my board I am going to use a transceiver (MAX2828), a power amplifier, a LNA and a RF switch. All these components are 50ohms I/O matched. So, my RF circuit consists about some RF components and some transmission lines to c

Transistor E2AFAA 89 08 274, need explaination please

Doing a quick look, I could not cross those numbers either. Is this used in a power supply (DC switch/rectifier) or an audio amplifier?

AC millivolt to switch DC relay?

Scott, I don't want to sound discouraging but it will be well nigh impossible to do what you want to do without some active circuits that may look fairly complex to someone with a limited experience in electronics. Do you care to share what you want to switch with the relay?

Problem with amplifier drone

Your PC mains adapter is a switch mode power supply, this means that inside it there is an oscillator(the source of your drone). Any difference in power consumption changes the frequency/mode of oscillations. To stop the oscillations annoying other users on the same mains supply, there are filtering circuits that stop the oscillations (...)

What's the peak-average-ratio of RF switch controlled PA?

The reason of the PA failure is not the switch itself, is the bursty operation of the power amplifier, which results from switching its input power. In this mode there is possible to appear overshoots in the output power (and collector/drain current) which might destroy some PA's if they (...)

class E power amplifier

I'm implementing class E amplifier in 130nm process.I have 100mv input signal and approximately 400mv of threshold voltage.Class E amplifier acts as ON/OFF switch when it is biased at threshold voltage.When I biased the circuit at threshold voltage the output is at 1.3v DC and voltage is not amplified (vout peak-peak=15mv).The transistor is (...)

RF pin diode switch design & parts

are you planning on switching the switch position while it is seeing 20 watts?

An RF Class E Amplifier

The DC resistance of the choke would be the least issue making the transistor getting hot. Actually in Class-E the value of the choke inductance is higher than chokes in other power classes. In Class-E to make the transistor working as a perfect switch (which means best efficiency and lower temperature of the transistor) the Q of the series C and

Question about drain current of a Class E PA

Here is a question about the drain current in a Class E power amplifier. There is on and off state for the switch CMOS transistor. When it is on, the transistor is turned on and current will be dumped directly from the power supply through the RFChoke inductor and the transistor to ground. 1. So is this just a huge waste (...)

Class E Power Amplifier

How to operate a HBT as a switch in AWR with Vce(sat)=5 volts and Ic(max)=40 mA and hfe(min)=140 ??

SP or PSS+PSP to measure input/output/inter-stage impedance?

I am trying to measure input/output/inter-stage impedance for a Class E power amplifier working at 433MHz (switch mode PA) in Cadence. Should I use ZM in SP analysis or ZM in PSP analysis? Which one is correct? ZM in PSP analysis. Here you have to consider that operation points of circuit is affected b

Signal Detection Audio Switcher Circuit

I'm confused. What exactly are you trying to switch? Is it the power supply, the loudspeaker signal or a low level audio signal prior to an amplifier. The original schematic is just a signal operated relay, it would turn the relay on whenever enough audio was presented at the input jacks and turn it off again after a short break in sound. (...)

class D and class AB for Rf power amplifier

Class-A,AB,B, and C are transconductance amplifiers and included in linear range PAs. Among these amplifiers Class-C has highest efficiency but lowest linearity. There is a trade-off between linearity and efficiency. For high efficiency you can choose switch-mode amplifiers which are unlinear basically, such as class-D,E and (...)

Swiching mode or linear mode (saturation)?

A Class E power amplifier working at 433MHz I am designing has a class F driver stage. I am pretty sure the transistor in output stage works as a switch (nonlinear, triode and cutoff mode). How about the transistor in the driver stage? Does it work in Saturation mode (linear) or switching mode (cutoff and triode)? Main (...)

Power amplifier (10w)- half power and full power option

hi, we are developing one power ampr (10WATTS) at 2100MHz with gain 30dB. In the spec they have mentioned features as HALF power, FULL power OPTION, switch SELECTABLE. i didn't understand this, can anybody help me in this?

How to switch a LDMOS Power Amplifier quickly?

I have designed a power amplifier of 25W using LDMOS devices. Most of the specifications are already OK, except for the switching time ON/OFF which should be less than 10us. Can anyone give some advice for swithing the LDMOS power amplifeir so quickly?OR can anyone provide a circuit to drive the gate of LDMOS to satisfy the (...)

Power and Data over 2 wires

Hi Use a low ohm resistor (10 ohm or less) in series with the + line connect a short switch (best on power mosfet + driver ) after the resistor between the + and Gnd.(shorting the PSU when conducting) the resistor is power limiting and for avoid shorting the power supply Connect a current sense (...)

power mos transistor switch

Hi, Could you give more details? Where do you need a switch in your RF amplifier? You can use MOS as a switch but you need a gate driver circuit to switch it.

ADS simulation of cmos class E power amplifier in 0.18um

-Class-E amplifiers are switch mode amplifiers therefore you should select the transistor which will have low Rds ,low Cds and Cdg,high Ft but the Drain surface will able to carry the drain current.There are some trade-offs between these parameters but there should be an optimum one. -Second thing is that, simulating Class-E (...)

why so big swing at output of buck converter

I'm a biginner of switch power supply circuit. The picture buck.jpg is the top circuit. I want to achieve a 3.3v at vo node. vob node is referenced at 0.5v, and sent into negetive input of error amplifier, and the output of amp is compared with ramp siginal to generate PWM siginal.PWM is sent to driver to generate LDR and HDR siginal, (...)

buck converter start up swing at output

I'm a biginner of switch power supply circuit. The picture buck.jpg is the top circuit. I want to achieve a 3.3v at vo node. vob node is referenced at 0.5v, and sent into negetive input of error amplifier, and the output of amp is compared with ramp siginal to generate PWM siginal.PWM is sent to driver to generate LDR and HDR (...)