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90 Threads found on edaboard.com: Bjt Frequency
Hi all, we are need a bjt Model file 250nm, for Tanner tool v13. (urgent),.. anybody have the model file, please help us,.
Hello! I'm having a problem answering the following objective questions from my book about troubleshooting bjt amplifiers. For item 19, I answered A and D Assuming the coupling capacitor is open (either the input coupling cap or output coupling cap) the ac output voltage would be zero. But if the bypass capacitor is open the ac output volt
hi, To keep the cost down I would use a 555 timer as a PWM generator for each chain. For only 20mA per LED chain, from a 24Vdc source, a bjt or a 2N7000 MOSFET would be suitable. The frame frequency of the 555 PWM generator could be selected for each LED colour chain. Lots of simple circuits on the web.
Dear all, recently I need to buy some discrete MOSFET devices with cutoff frequency round 2 GHz. But I found most vendors only offer discrete bjt transistors with cutoff frequency (or transit frequency) specs. Could anyone kindly suggest me where I can find some MOSFETs with explicit fT? Thanks,
For the receiver you can use a direct conversion front-end, which could be a simple additive bjt mixer with RF going in the base, oscillator injected in the emitter, and audio output from the collector. The receiver local oscillator could be identical with the transmitter oscillator, using also a 27MHz crystal. The frequency of the RX oscillator sh
Although you can use a bjt, I'm with Crutschow that the Mosfet is a much better alternative. Not only from the lower drive losses, but because of the absence from secondary breakdown that plague bjts.
Hi all, Tell me which software or hardware with specifications will be used to design rf amplifiers by using microwave:-D bjt and a frequency doubler using microwave FET. Thanks, Kartik
Hi I couldn't understand the magnitude frequency response of a bjt CML. If I add a voltage ac source, two poles are observed from the single-ended voltage magnitude plot. 113914 113915 If I add a current ac source, the single-ended voltage magnitude plot is like below. 113916[/
hi, Its usual to have an application in mind when starting to design a bjt amplifier. eg: DC or AC amp, output power , frequency range , impedances etc. What application are you considering.? E
Hi All, I am using the circuit from this paper in designing a PTAT circuit "A Novel Wide-Temperature-Range, 3.9 ppm/C CMOS Bandgap Reference Circuit",by changing the input transistor of opamp from MOSFET to bjt. This is the PTAT circuit and the detailed schematic of Opamp. Startup circuit is not included in this figure. 104978[/
For any amplifier (GaAs, CMOS, bjt, SiGe, etc) the 10dB difference rule between IP3 and P1dB is valid ONLY if the amplifier has proper bias termination and filtering at frequency equal to f2-f1 in a two-tone test.
103053 Here is a BC847 bjt datasheet from NXP. It specifies the noise figure of the bjt. But I can't understand the test conditions, especially Rs, f and B. What do the three mean, and how do they conduct this test?
Which one would be the easiest solution for a beginner in this situation? y kersleywyy, you are asking for the best solution? Very hard to answer. There are various alternatives for an 30 MHz oscillator: With bjt or opamp, with RLC or RC or crystal,.. One critical point that has to be clarified is the question of
Hi its like boost converter, It will have a MOSFET or bjt a high voltage switching device inside it and that will be clocked in a high frequency like 52khz, the switch will be connected series with a transformer on your need... The output duty cycle will depend on the feedback voltage.. And most of it will have a option like OFF/ON.. Look some typ
Probably schematics is worst. I recommend instead L3 resistor some kilohm, R3 C1 may be you don`t need at all. And you can try series 10ohm resistor with bjt emitter.
Hello! Who knows sot363/sc70 marked U33 and QFN 1098 N?FA3A. U33 should be one stage FET with working frequency up to 2-3GHz ( may be bjt two stage ) from Avago, RFMD and so on. 1098 some driver two stage bjt (SiGe tehnology? )1 st pin input and so on. - - - Updated - - - Concerning U33 I identify. It`s
IRF510 is a Power MOSFet but BLW30 is a bjt.They are not direct replacements. Even if you re-design the bias circuit to get the right OP, MOS and bjt chararactics are so different.Re-design your Power Amplifier with your new transistor is much easier. I'm sure there are app. notes for that frequency band,you may apply one of them..
I wonder why it's necessary to use 200 or even 500 kHz for LED dimming? Apart form the many right things that have been already said about MOSFET's versus bjt for fast switching, there's another rather simple point. bjt need to be operated with sufficient base current to achieve low saturation voltage. Do you know where you get the base current
I prefer to think in terms of current, when it comes to bjt circuits. This is a preference, theological arguments abound. For a high frequency amplifier, a high impedance DC bias bypassed with high quality C (emitter, and base coupling) is probably the ticket.
Hello, I have been trying to make DC-DC Buck Converter but now actually after knowing more about its complications, i would like to know how to get maximum switching frequency of any Bipolar Transistor or MOSFET ? Because in datasheet its maximum switching frequency is not written. What is Transition frequency given in the datasheet ? (...)
1. FET shows poor performance at high frequency 2. FET has small gain-bandwidth compared to bjt 3. FET shows poor voltage gain 4. FET can be operated only in low power applications
Two more tutorials, focused on bjt amps.
Hello, Fig 13, page 9 of this app note shows an improvement on the "normal" optocoupler feedback connection for transformer isolated SMPS's..... ....On page 9 it says that the opto diode is driven by a current source. Does this configuration, with the extra bjt, Q1, absoluteley
88276 Hi all, this circuit seems almost retro this days,but no one seems to know how exactly it works.can any one help me understand more about ringing inverters. On which factor does its frequency depends on ? How can i design one for a specific power. please help.
BF862 is a JFET and is very good for your application. JFET's have much lower noise than any other transistor type (bjt, MOS, GaAs) at low frequencies.
Supposing i am switching a BC847C bjt ON with just 100uA of base current. Suppose also that i have a large value collector resistor such that the collector current is also only 100uA when the BC847C is this an OK scenario?, or do bjts have minimum currents (Ic & Ib) below which they do not work properly? BC847C datasheet
A push-pull output stage doesn't need transistors with particularly low-noise figure if it's inside the feedback loop. Overall amplifier noise will be dominated by the input stage. Silicon bjt have generally a low noise corner frequency (in a 10 or maximal 100 Hz range). Most modern small and medium power transistor have little excess noise abo
I don't think that your circuit design alternatives are clearly described. "Totem-pole" drivers are rarely used in MOS circuit design, thus I'm not sure why you consider it all. It's a classical single polarity bjt topology, e.g. used in TTL logic.
hello, I am doing a flyback SMPS, and using the clock ramp of the pwm controller to derive the ramp for slope compensation. I am using a bjt to buffer the clock signal, as i dont want to load the clock down and mess up the performance of the controller. ...here is the bjt shown buffering the clock ramp.... bjt to buffer the (...)
for basic BANDGAP core (VBE+deta(VBE) structure using two bjt, a resistor, two PMOS, an opamp to force Vip=Vin), how to analyze the PSRR+ (vref/vdd)? in my simulation, in 300KHz or so, two poles appear (close to each other), and the PSRR+ becomes positive, that is, vo/vdd>1 in some frequency range (300K ~ 600K), why? what is the possible reasons? w
Presumed you are talking about FET (MOSFET or JFET?) versus bjt, the question is meaningless without specifying a frequency range and application. Also the term stability can mean a lot of different things. Using ambiguous terms is a perfect way to get people talking at cross purposes.
Why not use your 1.5A high speed driver, {LTC1693} instead of the cheap bjt's {2N3904} to drive U1?
Cb abd Ce are simple HP filters that AC couple the RF signal with low inductance. Of course bjt's use current gain, FETS use Voltage gain., Op Amps use Voltage Gain.
HI i have to design a 3 stages bipolar amplifier, with overall transimpedance gain of 16 000 V/A ,experimental cut off frequency of 200 kHz and AC current imput of 0.1 mA p-p. any help of how i should start???
I mean, JFET, bjt, GaAs FET, CMOS, have totally different flicker noise corner.
Hello, S parameters for CE bjt can easily be manipulated with maths to produce the S parameters for CB CC etc and vice versa. I believe Wes Haywards introduction to radio frequency design describs the Math.
Allright,but can somebody explain to me why in all books when they subsitute a circuit with bjt devices to it's small-signal low-frequency equivalent they write next to the voltage contolled current source either gm*uπ or β*ib (implying that those quantities are equivalent)? If the equation gm*uπ=β*ib i
No. There are some bjt transistors that have been designed for Mixer application only.Their characteristics are optimized for mixers. Look at NXP's wide-band transistors..;
This wide frequency range is not an easy task. Can use a push-pull Norton amplifiers as in the example attached. Can get better than +50dBm OIP3 using a pair of medium-power high-frequency bjt's. Circuit like this can work between 3MHz and 150MHz. Would be a real challenge to make it work at higher frequencies, mainly due to the roll-off (...)
Recently I met an interesting question for RF amplifier design. As we know, by adding a series inductor at Emitter, we can increase the stability of a bjt Common-Emitter (CE) amplifier. When it comes to a Common-Base (CB) or a Common-Collector (CC) amplifier, what should we do to increase its stability? .......................
You'll need a properly designed mosFET/bjt class A/B amplifier driving hi voltage biMosfets in a full bridge configuration to your load, this allows a 1500 volt rail max and the bandwidth and rise times you require, a transformer step up will not give you the edges you require - Regards, Orson Cart.
Basic bjt Amplifier Configurations
hi, i m desiging colpitts oscillator schematic in simulink/matlab. i need to use radio frequency coil (rfc) for the circuit.but there is no such option in simulink. so i m trying to use inductor in place of rfc. how much value of inductor to use as rfc for 2mhz bjt colpitts oscillator to get good sine wave. or if anybody give me readymade s
hello Do you know of any articles which tell how to understand the following CCFL driver circuits........ Page 1 = CCFL circuit:- I cannot understand why they all use bjt s as the switching devices. MOSFETs have far better high frequency switching performance.?
Hi all, I trying to design a simple bjt mixer AM receiver. I tried many circuits found on the internet but I want to design my own circuit with the LO injected through the emitter and the IF out through tuned circuit on the collector, but I have quision: What is the non-linearity that should be used? is it V-I of the base-emitter junction, sa
Generally, at the lowest frequencies JFET is lower, then at higher frequencies bjt is best and at still higher GaAs is best. Ordinary MOSFET is generally worse than these three at any frequency. They are used because the IC process on silicon has the smallest number of masking steps for MOSFETs. This smaller masking steps causes or results in lowe
you should also take a look on the frequency response of your circuit. It could be (it depends on the frequency of "speed") that you need an specific mos/bjt to convert it as fast as you need!
The TL431 can be replaced with a circuit based on discrete components such as Zener diode, opamp and bjt/MOSFET OC/OD transistor .. Have a look at the attached picture .. IanP :|
Dear all, I would like to design an up-conversion mixer using bjt@HBT for very high frequency say the LO about 30GHz. Can anyone expertise out there help me how to start designing the device? What is the very first step that I should consider? What is the best simulator can be used? Thanks in advance
I have tested this circuit several times. I often ends up with a maximum f from 30 to 50 kHz. Like mentioned before, stray capacitanses and inductances make the circut unsuitable for higher frequensis. Besides of that, I think your bjt is more of use in audio amplifier circuits. Also the output pulses will not be rectangular, but rather smooth -


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