First and second harmonic generation The root cause of harmonic generation is caused by nonlinear loads. When current flows through the load, it is not linearly related to the applied voltage, and a non-sinusoidal sinusoidal current is formed, thereby generating harmonics. The harmonic frequencies are integral multiples of the fundamental frequency. According to the French mathematician M. Fourier, the principle of any repetition can be decomposed into a sine wave containing the fundamental frequency and a series of harmonics that are multiples of the fundamental. Component. The second harmonic of Band 40 TDD-LTE requires -30dBc or less. In order to ensure the test at high and low temperatures, the terminal manufacturer will ensure that the second harmonic is below -36dBc at room temperature. The harmonics generated by the Band 40 TDD-LTE amplifier are as follows: : The typical suppression of the second harmonic in the B40 filter on the market today is about 24 dB. Theoretically, this filter is sufficient to suppress the second harmonic. In the actual B40 TDD-LTE terminal project, the insertion loss of the power amplifier output to the antenna output port is 4dB, then when the antenna output is 23.5dBm, the output power of the power amplifier is 27.5dBm, and the second harmonic at this time can fully satisfy - 30dBc standard. But in fact, because the device is non-linear, the filter switch also has such a problem, plus the irregularity of the PCB Layout trace, the actual test of the project, the second harmonic result is -28dBc, can not meet the standard. Second, LC filter simulation and debugging This project uses the LC passive low-pass filter to effectively suppress the second harmonic of the signal. The filter is constructed only by the principle that the reactance of the capacitor and the inductor component changes with the frequency, and the advantage is that the circuit is relatively simple, does not require a DC power supply, and has high reliability. In the design of this project, the π-type matching of the filter backend is shown in Figure 3. After ADS simulation, the suppression of the second harmonic of the filter is shown in the curve shown in Figure 4: the red curve indicates the insertion loss of the L-type matching at 2.0 GHz to 5.5 GHz, and the blue curve π type matches the insertion loss at this frequency interval. . We can compare that π-type matching has better in-band insertion loss and out-of-band rejection, which is the best choice for this project. Using the π-type matching scheme provided by the simulation, after actual debugging, when C1 is 1.2pF, L1 is 2.4nH, and C2 is 1.2pF, the second harmonic is optimally suppressed. The data is shown in Figure 5. Third, the conclusion This paper mainly solves the second harmonic problem of Band 40TDD-LTE by adopting LC filter and ADS simulation and adopting effective matching method.
·Basic precautions
Do not put expensive oil into low-quality cartridges to avoid wastage. Most pre-filled oil cartridges have the so-called 510 thread. The oil cartridge screws onto a rechargeable battery. Some of these batteries have buttons and some heat up automatically when you pump the oil. Some batteries have multiple temperature settings and some heat up to a preset temperature; these features need to be known in advance.
·Cleaning notes
Use a suitable cleaning tool to clean them, such as activated charcoal or dried tea leaves in a used pipe to absorb the oil. It is important not to use alcohol or other boiling water to clean the pipe, and to wait until it has cooled down completely before cleaning. Otherwise, the hot stem will come into contact with the watery liquid and cause the mouthpiece tenon to loosen, thus shortening the life of the 510 cartridges.
This is what you should be aware of when using 510 cartridges. At the same time, when using 510 cartridges, there are still some vaping tips, for example, when using them, be careful not to suck too hard, will not produce smoke. When you inhale too hard, the smoke is sucked directly into your mouth and not atomized by the atomizer, so gently inhaling is more powerful and gives you a better vaping experience.
510 Cartridge Oem,Leakproof 510 Cartridge,510 Battery And Cartridges Oem,510 Cartridge Shenzhen MASON VAP Technology Co., Ltd. , https://www.disposablevapepenfactory.com
