The ceramic filter is made of lead zirconate titanate ceramic material. After processing, ceramic materials are made into thin sheets, and both sides are plated with silver as electrodes. After DC high voltage polarization, it has piezoelectric effect. According to different circuits, filters can also be divided into LC passive filters, RC passive filters, passive filters composed of special components and RC active filters. LC passive filter: It is composed of inductance and capacitance, and has good frequency selection characteristics, low signal energy loss, low noise and low sensitivity. Disadvantages: Inductive components are bulky, inconvenient to integrate, and have low quality factor (poor frequency selectivity) in the low frequency and ultra-low frequency range. RC passive filter: Compared with LC passive filter, resistance replaces inductance, which solves the defect of large volume, but this kind of filter has poor frequency selection characteristics and is generally only used as a low-performance filter. According to the amplitude-frequency characteristics, it can be divided into band-stop filter (also called notch filter) and band-pass filter (also called filter). It is mainly used in frequency selection network, intermediate frequency tuning, frequency discrimination, filtering and other circuits to achieve the purpose of separating currents with different frequencies. With high q value, amplitude frequency, phase
Good frequency characteristics, small size and high signal-to-noise ratio. It has been widely used in color TV, radio and other household appliances and other electronic products. The principle and category of ceramic filter mainly use the piezoelectric effect of ceramic materials to realize electrical signals. Mechanical vibration? Electrical signal conversion, thus replacing the LC filter circuit in some electronic circuits, making its work more stable. At present, the structures of ceramic filters can be divided into two categories: two-terminal and three-terminal.
The common types of bandpass filters in color TV sets are ceramic filters of LT5.5M, LT6.5M, LT6.5MA and LT6.5MB, and the 10.7MHz IF filters commonly used in FM stereo recorders and radios are LT 10.7MA and LT 10.7.
MB, LT 10.7MC, etc. The IF filters of AM radio include LT455 and LT465, etc.
Filters have the characteristics of stability and good anti-interference performance, and are widely used as frequency selection components in various electronic products such as televisions, video recorders and radios. It has the advantages of stable performance, no adjustment and low price, and replaces the traditional LC filter network.