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Hi all, What does impedance transformation mean with regards to antenna? Is this transforming the input impedance(Z11) of an antenna to the desired value? Can an L section using lumped components manipulate the resonant frequency of an antenna? Regards, Vineeth
What does impedance transformation mean with regards to antenna? For most folk, this means to alter the driving point impedance by adding some sort of matching scheme. This is usually a network of matching components/devices , between the the energy source and the antenna driven point. Stretching the meaning a little, it might
i need to design a Coaxial impedance transformation which as a part of a complex antenna ,but i am not sure about the feed in feko. i use the waveports,then meshed it has wrong in the port.could anybody can give me some suggestion.plz
Could I use this kind of impedance transformer to do this? Yes. In fact there are no alternatives to a transformer, preferably a transmission line transformer.
Hello, Is there anybody who already designed a PA that should drive a SAW filter ? Should we provide a particular output impedance to the SAW to reduce VSWR ? Lots of design papers says that you should transform the load to the optimum load to have best efficiency. Suppose I have a 50Ohm SAW filter that is terminated with a 50 Ohms impedanc
This post is about impedance matching of Rf power transistor, these power transistor usually have low input/output impedance like z= 2.1 - j3.9, The first question is that what is the usual practice for matching this low transistor impedance to standard 50 ohm, Is single stub matching is the only preferred choice for complex to real (...)
Hi all, I have some questions to ask about optimum load impedance in power amplifiers designs. As can be seen from the attached figure, in order to obtain maximum output power, we need to use load-pull simulation to find an optimum load impedance (Zopt). Then, we design an impedance transformation network to transform (...)
In fact this is not balun configuration, because pin 2 of SA612 is AC connected to the ground (reactance of 100nF looks almost as a short at RF frequency). This is a capacitive tap impedance matching, which is using the formula as in the attached picture (this is valid only if Rs < If
Dear All,,, I have a question regarding the basics of transmission lines... If there is an RF source with rms voltage of (Vg) and an internal resistance (Rs) connected to a quarter wave transmission line terminated by an open circuit. Now since the RF source would see a short circuit at its terminals because of the impedance transformation o
Hello I consider the attached image which is the first stages of a regenerative QRP receiver. The amplifier comes from another project and output impedange is 50 ohm. The detector assumes an imput impedance of 50 ohm I think as well. Since I would like to combine these circuits, I would like to migrate the output transformer of the rf amplifier w
What frequency range can I rely on FR4 for relatively constant characterikstic impedance then? The permittivity (eps_r) of FR4 varies, and this means that line impedance varies. This is independent of frequency. However, you only care about line impedance when the line segments have a certain criticial l
It is the delay, that causes impedance transformation. Use any cable impedance as long as its length is correct relative its velocity factor, which can differ between different types of coaxial cables.
Yes, there can be different impedance (or return loss) at antenna connector and the other side of the feeding transmission line. This is the reason that have to keep tracking the impedances all over the transmission path. Usually the RFIC manufacturers provides the impedance (S parameters) at particular pins of the IC package, and not behind (...)
So even if the matching network is lossless how can i say that no power is lost in the impedance transformation network as soon as a portion of it will be reflected back? The idea is that reflected signals cancel. Or in other words, the load impedance Zl should be transformed by the quarted wavelength line,
Hi, I am working with a simple class D RF PA targeting a centre frequency of 2.5GHz.(Bandwidth not the concern at the moment.) . So its basically an cmos-inverter driving a 50 ohm load. And I have added L and C in series in between the Load and the inverter output so that the resonance frequency of the series RLC is 2.5 GHz. My question is that
So you want to impedance match a radio with antenna for maximum efficiency and have a transformer somewhere along the line. impedance matching can be done on either or both sides of transformer. It is only a question of what is the most practical alternative. Assume components have been added resulting in conjugate match between antenna and transfo
I need information on toroids for 1-40MHz applications mainly related to impedance transformation. Where can I find the information on general toroids, windings, ... etc madhukar
BalUn is a device to transfer the energy from Balanced-to-Unbalanced (or vice-versa) configuration. Differential amplifiers , dipol antennas , mostly mixers etc use Balun. For instance 50 Balanced input impedance can be converted 50 single ended Unbalanced input/output. Additional to , it may serve a impedance matching function but it's not
There are lots of companies that have surface mount PCB transformer. You can choose the impedance transformation ratio and the operating band.
There are all sorts of passive networks that can change one impedance into another. The audio transformer is one example. Pi and T LC networks can also change the phase angle. Matching is a special case of impedance transformation where the new impedance is what you want. That is, you design the network to get the (...)
It is also the very simplest divider. It has large bandwidth if compared to other kinds (gysel or rat race), and the bandwidth can also be broaded inserting more λ/4 sections. In fact just one λ/4 section could make the impedance transformation, but if the "jump" is big (e.g. in a 10 ports divider/combiner you have to realize an i
Hi Iam having problems with differential Lna simulation in spectre. I have designed a matching network that would step down the impedance to a low level . After that i have used an ideal balun from the rf lib and tried to simulate it. I also tried with a VCVS.Neither of these seem to work. My S21 is a straight line . BTW the impedance tran
In CMOS PA design one trick that could be done is to use multistage output L networks, to decrease the insertion loss and improving indirectly the efficiency. Multistage L match may have lower insertion loss if the reactive component or components have low Q, even though the impedance transformation ratio is not high. The loaded Q of each stage s
impedance transformation is must for patch antenna array for proper Powerdivision among the antenna array elements. Feednetwork behaves like Wilkinson powerdivider. U can analyze this from the example given in IE3D manual.
try using a impedance transformation circuit(i.e. L-match Π-match etc) to transform the 22 ohm to 2.2k.....
The DC feed is basically used to feed with DC the balanced inputs (or outputs) and should have minimal effect on the balun performance. Of course, those feeds/teeminals can play a vital role if they are used in the impedance transformation, but 50:50 Ohm conversion will actually require AC gnd for those nodes... --padpan
@FvM ... what diff amplifiers do you use and where do you get them? @eecs4ever ... datasheet of you ADC usually suggest a wideband transformer, if not, choose one from Mini Circuits. Watch out for the correct impedance transformation and termination.
Balun or impedance transformer?? Balun!
what will be the impact on RF performance? It all depends on the length of the line relative to the wavelength. If the line is 1/20 wavelength or shorter (effective wavelength including substrate epsilon), then the impedance transformation due to the wrong Z0 can be neglected. If your line is longer than that, you
Hey, I have to design a power amplifier in 130 nm technology witht he following specs Power Output: > 23dBm (at PA output) Total Power Consumption: < 0.5W @ 16dBm CW output power RF Input Signal @ 2.45GHz : 1Vp-p sinusoid if single ended -- differential or single ended 1.414Vp-p if differential Input Source impedance 50 
Change port 2 and 3 to 25 ohm differentially. Or use configurations for impedance transformation.
I'm not quite sure but I think that two twisted pairs would be winded on the core. You use twisted pairs to get a transmission line transformer for higher frequency operation. This is equivalent to reducing the parasitic capacitance. I assume the unconnected winding is one of both threads of the primary that is not used because a 4:1 impedance tran
Hi, I design a two stage UHF amplifier, 2Watts. I have a problem two achieve a wideband interstage matchig. The optimum output impedance of the first stage is R=U^2/2P => R=100 ohm while the optimum input impedance of the second stage is only 4 ohm. With such a large impedance ratio it is very difficult to achieve wideband matching. I (...)
Both parallel capacitor pairs have to be tuned while the series capacitors are setting the impedance transformation ratio. 68 pF surely isn't correct, it's 2 x 68 pF each in the NXP application note. In my opinion, a 50 mm coil should rather have 4 than 2 turns, and it's not suited for distances above 50 or maximal 70 mm anyway, even if perfectl
I am confused by this post. The reactive power splitters I have used have S21 = S31. And they work fine as power combiners too. Working as a splitter, a 50 ohm source comes up to a T junction. At that T junction, looking one way, it sees 100 ohms resistive. Looking the other way it sees 100 ohms resistive. When the two paths are combined a
I agree, that a LC series or parallel filter at an impedance level of e.g. 50 ohm involves unhandy L and C values. Usually bandfilters are build as a parallel circuit with high characteristic impedance (kohm range) and impedance transformation to the signal path.
This is the all idea of tapped line, to provide an impedance transformation. So you have to tune the filter design (length, spacing, width, etc, of the resonators) in the way that at the tapped point the impedance is nearly 50 ohms, meeting in the same time all the other parameters of the filter, insertion loss, rejection, bandwidth, (...)
I checked, that the site is working. Here's the direct tool's link: But the tool is for inductance calculation only, not for design of resonant circuits or filters. I guess, you intend a matching circuit like the below Philips/NXP application? Viewn from the coil, the parallel and series c
Hi, all, Let's consider a 50 ohm to 200 ohm impedance transformation SAW filter, and it has the insertion loss of 1dB. If it is inserted between a 50 ohm antenna and a 200 ohm LNA, will it help with the chain noise figure, or the noise figure of SAW+LNA will be better than LNA alone (refer to 50 ohm)? Please let me know your calculation, if y
generating the current required for the effective reception of the signals I guess you are talking about driving the reader coil? It can be expected as an inductive impedance, and surely not a "resistive load of 19 0hm" as annotated in the circuit diagram. But the circuit also misses any means for RF modulation. It would be better
the linecalc only calculate the width of feed line at one operating frequency,doesnt it? The change in the line impedance over frequency is very small.
In my opinion, the function of the "red" quarter wave transformer is impedance transformation. C is required to block the DC. If the Z0 of the "red" line is above the reference impedance, and less then quarter wave length, the combination of "black" and "red"+C sections may be part of a 2nd order band pass filter (with good return loss). (...)
It goes like this: C251, C251 are DC block L251 is used to compensate some internal cap, to have a real differential impedance C252, L252, C262, L261 is the real balun; it gives a 90 deg phase shift on each branch (with opposite sign) plus a certain impedance transformation. C253, C254, C255 probably a match to 50 Ohm plus some filtering (...)
You can also put a match stub on port 2 and port 3 to adjust VSWR of S22 and S33. ---------- Post added at 22:47 ---------- Previous post was at 22:46 ---------- Or a impedance transformation microstrip at port 2 and port3.
Power amps have a fairly high input line level (~1V?) and an impedance that is mismatched to sources like mics and guitar pickup coils. Preamps may perform not only gain, but impedance transformation as well; they may include shaping of frequency response (like a RIAA phono preamp). The noise qualities may receive more attention (...)
What will happen if I don’t place them? This is a lowpass filter, to meet the regulations (out-of-band transmitted power). Depending on the values, it can also be used for antenna impedance matching.
You can excite the 0.125lambda loop with another loop (as you mentioned). You may ground the middle of the loop and use a tap on the loop (delta match). Other option is to open the loop in the middle, connect one end to ground and one end to ground via a capacitor. You can feed across the capacitor. From a simple lumped circuit approach, the ratio
Ok. The heat sink is grounded to the housing. so that is good. I know the coax has an effect on impedance, but it is hard to believe that my cable RF connector would cause any problem. Any other RF connector is constructed basically the same. I have heard about fake RF transistors. I did get it from China. I tested the RF transistor with my Wavetek
Hello I am designing a matching network to transform a 50Ω source to a complex impedance 300-j450Ω. I want a BW of 100MHz. My center freq is 1.42GHz. I use the formula Q=f0/BW, to find the required Q for my matching network. It is calculated to be 14.2. But if i design it this way i cannot achieve the BW i want. I need to design for Q=3
for crystal model ( C , L, Rs ) in series L = 3.5m H (offchip xtal component) Rp (transform) = (wL)^2/Rs this is huge value for w =120M Hz, Rs=50 ohm--> Rp=1.4*10^11 ohm so i need a circuit where the crystal should see w very large Z to prevent decreasing the Q heavily or what ? can any one help me in this