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Hi All,
I have a question about the SSB (single-side band) modulation signal, and its circuit implementation in Radio.
For example, the baseband DAC has two I/Q differential signal outputs, and then they are connected to the corresponding differential amplifiers, and to the I/Q mixer...
Most of the antenna companies are now working on quad-band, or even penta-band antenna.
Basically the PIFA/monopole type antennas with some matching circuits would work. Of course, the VSWR/RL usually is not as good as the single band antenna. But 2.5~3.0 VSWR / 6 dB RL are generally acceptable.
I believe 4W is not a big problem. If I remember correctly, most cell phones have up to 30~33 dBm conducted power.
But of course, if your antenna is directional, don't point the main beam to yourself....
I am wondering how can I calculate that? Are there any formula to do so?
The other issue is that why the matching resistors do not contibute addtional noise to the output? If these resistors is hotter (due to the heat dissipation), are there any negative effects? If yes, how can it be accounted...
Hi, I have a question about calculating the noise figure of a balanced amplifier circuit, as shown in the attachment.
In this case, two LNA is followed by a 90-deg hybrid coupler splitter, and one more 90-deg hybrid coupler combiner is used to combine the signals. If assume the gain and noise...
Hi, everyone. I have a question about the minimum component spacing in the automatic pick-and-place assemble process.
Let's say that I design a complete circuit with all kinds of components, with QFN, TSSOP, SOIC ics, and 0402,0603,0805 capacitors and resistors. So how close those components...
Just a simple simulations for the above situation, it gets:
S11=-6dB (25%)
S21=-3dB (50%)
It means that if the resistor is working, half of the input power from port 1 goes to port 2, 25% of the input power reflected back to port 1.
Where is the rest of the 25%? Because wilkinson power...
I have a simple question about the spectrum analzyer.
Is it used to measure the power spectrum density(PSD), so the measure output unit should be dBm/Hz or W/Hz?
But it seems the real world spectrum analyzer output is dBm. So how can it convert back to the PSD? Is it related to the IF filter...
Hi, I have a general question about PCB manufacturer.
The fab house told me that when I use 1/2OZ copper foil (.7mil) on external layer, after plating additional copper for PTH, it goes to about 2.2mil. Is that true?
What are the minimum copper plating thickness? Does it depends on the PTH...
Hi, I have a question about RF LNA chip test procedures.
The LNA have been soldered on the PCB, with RF in, out connected to SMA connectors, and DC pin to regular connector. It is self-biased MMIC LNA operating at 5.8GHz. In order to test its small signal gain and P1dB, what are the test...
intermodulation order
Hi, I have a question about the third order intermodulation product (IP3).
I understand that for two single tone signals at f1 and f2, the IP3 appears at 2*f1-f2, and 2*f2-f1. But if those two signals are modulated, with frequency f1_Low~f1_High, and f2_Low~f2_High, what...
Thanks Dipnirvana.
Another questions about the decoupling capacitor. Can I just connect the 0402 100pF capacitors adjacent to each Vdd and Vgg, and then tied them together, and connect the tantalum 2.2uF capacitors at the common joint?
In this case, the 100pF provide some decoupling between...
a question for pcb
Hi, everyone. I have a question about the PCB layout for a 3-stage single chip PA.
As shown in the attached picture, the PA is in QFN package, with 3 stage amplifier inside. Each stage has its own gate and drain pins.
In order to reduce the footprint area, I would like to...
pc spi
Hi, everyone. I am pretty new to embedded systems design, and have a simple question about letting PC to generate SPI signal. Are there any evaluation board that can enable personel computer to generate SPI signal?
Besides, right now I have a project for simple control signal. Are there...
gold plating pdf
Hi, I have a question about the PCB finish plating processing:
For the electroless nickel immersion gold plating (ENIG), is the processing like:
plating->etching->solder mask
For the electrolytic gold plating, is the processing like
etching->plating->solder mask
And can...
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