Surface Acoustic Wave Filter (SAWF)
Ceramic component
Structure and characteristics of ceramic components The ceramic element is coated with a metal silver layer on both sides of a sheet made of aluminum zirconate titanate ceramic material,and then make the electrode lead on the silver layer,and finally packaged with plastic and other materials.The basic structure,working principle,characteristics and equivalent circuit of ceramic components are similar to that of quartz crystal,but the frequency accuracy and frequency stability are better than that of quartz the crystal elements are a little bit worse.
Classification and naming of ceramic components.Ceramic components can be divided into ceramic trap and ceramic filter according to their uses and functions,ceramic frequency discriminator,Ceramic resonator,etc;the number of electrodes is divided into two electrode ceramic elements,three electrode ceramic elements and multi-electrode ceramic elements above four electrodes.Ceramic components are generally encapsulated in plastic or composite materials,and some are packaged in metal shell.
The main parameters of ceramic components and the main parameters of replacing ceramic components are nominal frequency,insertion loss and notch depth,distortion,frequency discrimination output voltage,passband width,resonant impedance,etc,when selecting and replacing ceramic components,as long as the model and the nominal frequency can be the same.
Surface Acoustic Wave Filter (SAWF)
Saw filter (SAWF) is an integrated filter,which uses the principle of "piezoelectricity" and "anti piezoelectric" to transmit signals.The ability of different frequency signals to transfer energy in SAWF is different,thus forming a filtering function for different frequency signals.
Structure of surface wave filter (SAWF)
Saw filter is composed of piezoelectric crystal substrate,input transducer and output transducer.Piezoelectric crystals are usually made of lithium niobate,and transducers are interdigitated.They convert voltage signals into mechanical waves,and then convert mechanical waves into voltage signals.The size and shape of the interdigital transducer determine the passband characteristics of the filter.
The characteristic of surface acoustic wave filter (SAWF) is:good selectivity,the absorption depth can reach 35~ 1 40dB;the amplitude frequency characteristic and the phase frequency characteristic are good,and need not be adjusted;the temperature stability is good,the aging is not easy,the overload ability is strong,it will not cause the change of frequency characteristic because of the size of the transmission signal.But it also has disadvantages such as large insertion loss,low transmission efficiency and 3 reflections.
Main parameters of surface acoustic wave filter (SAWF)
The main parameters of surface acoustic wave filter (SAWF) include central frequency, bandwidth,rectangle coefficient,insertion loss,maximum out of band suppression,amplitude fluctuation,linear phase shift and so on.