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70 Threads found on edaboard.com: Switch Power 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
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
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.
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 (...)
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)
the AC switch on the back of the pot would not meet today's safety standards....!
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
Which connector switch Sleeve? You are wondering why DC ground current causes ground noise? with 50mOhm spec @1A or after aging? or with low level signal or with inductive grounds and unshielded connector and signals? Pls show your problem with photo of layout and scope trace. ( assuming 2.5 or 3.5 mm stereo with Gnd switch )1
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 (...)
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.
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 (...)
When you tie the switch to gnd, Q2 turns off, Q3 turns on and buffer amplifier is supplied through this transistor.
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.
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 (...)
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
transistor or FET or MOSFET in common-emitter mode between the switch and power MOSFT
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 (...)
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
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 (...)
switching Class-E amplifiers use the transistor capacitance in parallel of the switch. When the switch is closed, all the current flows through the switch. When is open, this same current must flow through the capacitor. Best Class-E efficiency requires an upper limit of the transistor capacitance, and (...)
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!
The circuit can only work if the switch has similar low leakage as the amplifier. Did you identify a suitable transistor?
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 (...)
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 (...)
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?
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.
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
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.
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
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?
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?
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 (...)
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 (...)
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 (...)
are you planning on switching the switch position while it is seeing 20 watts?
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
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 (...)
How to operate a HBT as a switch in AWR with Vce(sat)=5 volts and Ic(max)=40 mA and hfe(min)=140 ??
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
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-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 (...)
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 (...)
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?
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 (...)
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 (...)
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.
-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 (...)
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, (...)
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 (...)