Filters are one of the key components in RF systems, primarily for frequency selection—passing unwanted frequency signals to reflect unwanted interfering frequency signals. A classic filter application example is the receiver or transmitter front end, as shown in Figure 1, Figure 2: As can be seen from Figure 1, the filter is widely used in the RF, IF, and baseband portions of the receiver. Although the development of this digital technology uses a digital filter to replace the analog band of the baseband part or even the intermediate frequency part, the filter of the radio frequency part is still irreplaceable. Therefore, the filter is one of the essential components in the RF system. There are many ways to classify filters. E.g: The characteristics selected by frequency can be divided into: low pass, high pass, band pass, band stop filter, etc.; According to the implementation, it can be divided into: LC filter, surface acoustic wave/body acoustic wave filter, spiral filter, dielectric filter, cavity filter, high temperature superconducting filter, planar structure filter. According to different frequency response functions can be divided into: Chebyshev, general Chebyshev, Butterworth, Gauss, Bessel function, elliptic function and so on. For different filter classifications, the different characteristics of the filter are described primarily from different filter characteristic requirements. The many different features of the filter described by this multi-classification method of the filter embodies the need for the filter in practical engineering applications, which means that the design needs to be comprehensive when designing for user needs. Consider user needs. When selecting a filter, the first thing to determine is whether a low pass, high pass, band pass or band stop filter should be used. The following is a description of the frequency response characteristics of high-pass, low-pass, band-pass, and band-stop, and their effects, which are classified by frequency. Butterworth Chebyshev bandpass filter Butterworth Chebyshev high-pass filter The most commonly used filters are low pass and band pass. Low-pass is widely used in image suppression in the mixer section and harmonic suppression in the frequency source section. Bandpass is widely used in signal selection at the front end of the receiver, spurious suppression after transmitter power amplifier, and spurious suppression of frequency source. Filters are widely used in microwave radio frequency systems. As a functional component, there must be corresponding electrical performance indicators to describe the performance requirements of the system for the component. Corresponding to different applications, there are different requirements for certain electrical performance characteristics of the filter. The technical indicators describing the filter electrical performance are: Order (level) Absolute bandwidth / relative bandwidth Cut-off frequency Standing wave Out-of-band rejection Ripple loss Passband flatness Phase linearity Absolute group delay Group delay fluctuation Power Capacity Phase consistency Amplitude consistency range of working temperature Vape Pen Disposable E Cigarette,Disposable Vape Pen Stick,Disposable Vape Puff Bar,Electronic Cigarette Vape Puff Bar Guangzhou Ouruike Technology Co., Ltd. , https://www.orelxvape.com
