Yüzey akustik dalga esasına dayanan filtre ve rezonatörlerin analizi ve tasarımı

Abstract

The applicability of surface wave devices to practical electronic systems is basically determined by the centre frequencies, bandwidths and delays obtainable. The upper limit for the centre frequency is determined by fabrication techniques, and current lithography is about 1.5 GHz. At low frequencies SAW devices become more bulky and expensive and other technologies become more suitable, for example bulk acoustic wave resonators for bandpass filters or digital techniques for signal processing. Consequent 1 y-, SAW devices are not normally used below a few MHz. In most applications this frequency range implies that the devices are used in the I. F. section of ' the system and this has the important consequence that low insertion loss is not generally a priority. For example, bandpass filters have typically 15 to 30 dB loss, and this is acceptable for many applications. Bandwidths generally range from a minimum of about lOO kHz to a maximum of about 50% of the centre frequency. CXIIZ)electrode position and the apodisation function required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters. Surface wave techniques can be used to produce several types of stable oscillator using SAW resonator. The resonator is basically two reflectors forming a surface wave cavity and a transducer which are used to generate a surface wave packet on the surface. The reflectors are periodic arrays of either metal strips or grooves and reflect when their period is equal to half the SAW wavelength and there is corresponding increase in the array transmission loss. With a large number of strips or grooves, the array reflection coefficient can be very close to unity. For YZCY-cut Z-propagatingD lithium niobate which has an impedance discontinuity of 1.2%, 300 metallic strips are required in the array for a reflection coefficient of 98%. The resonator can give very high Q factors, up to 20,000, giving good stability. Furthermore, highly stable c. w. sources with frequencies up to about 2 GHz can be obtained by using SAW resonators. In this thesis, it will be given an analysis and synthesis procedure using transmission line model for the reflectors. The basic resonator structure is illustrated in Figure 3. Grooved array reflector substrate Figure 3. Two-port surface acoustic wave resonator CXIDThe applicability of surface wave devices to practical electronic systems is basically determined by the centre frequencies, bandwidths and delays obtainable. The upper limit for the centre frequency is determined by fabrication techniques, and current lithography is about 1.5 GHz. At low frequencies SAW devices become more bulky and expensive and other technologies become more suitable, for example bulk acoustic wave resonators for bandpass filters or digital techniques for signal processing. Consequent 1 y-, SAW devices are not normally used below a few MHz. In most applications this frequency range implies that the devices are used in the I. F. section of ' the system and this has the important consequence that low insertion loss is not generally a priority. For example, bandpass filters have typically 15 to 30 dB loss, and this is acceptable for many applications. Bandwidths generally range from a minimum of about lOO kHz to a maximum of about 50% of the centre frequency. CXIIZ)electrode position and the apodisation function required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters. Surface wave techniques can be used to produce several types of stable oscillator using SAW resonator. The resonator is basically two reflectors forming a surface wave cavity and a transducer which are used to generate a surface wave packet on the surface. The reflectors are periodic arrays of either metal strips or grooves and reflect when their period is equal to half the SAW wavelength and there is corresponding increase in the array transmission loss. With a large number of strips or grooves, the array reflection coefficient can be very close to unity. For YZCY-cut Z-propagatingD lithium niobate which has an impedance discontinuity of 1.2%, 300 metallic strips are required in the array for a reflection coefficient of 98%. The resonator can give very high Q factors, up to 20,000, giving good stability. Furthermore, highly stable c. w. sources with frequencies up to about 2 GHz can be obtained by using SAW resonators. In this thesis, it will be given an analysis and synthesis procedure using transmission line model for the reflectors. The basic resonator structure is illustrated in Figure 3. Grooved array reflector substrate Figure 3. Two-port surface acoustic wave resonator CXIDThe applicability of surface wave devices to practical electronic systems is basically determined by the centre frequencies, bandwidths and delays obtainable. The upper limit for the centre frequency is determined by fabrication techniques, and current lithography is about 1.5 GHz. At low frequencies SAW devices become more bulky and expensive and other technologies become more suitable, for example bulk acoustic wave resonators for bandpass filters or digital techniques for signal processing. Consequent 1 y-, SAW devices are not normally used below a few MHz. In most applications this frequency range implies that the devices are used in the I. F. section of ' the system and this has the important consequence that low insertion loss is not generally a priority. For example, bandpass filters have typically 15 to 30 dB loss, and this is acceptable for many applications. Bandwidths generally range from a minimum of about lOO kHz to a maximum of about 50% of the centre frequency. CXIIZ)electrode position and the apodisation function required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters. Surface wave techniques can be used to produce several types of stable oscillator using SAW resonator. The resonator is basically two reflectors forming a surface wave cavity and a transducer which are used to generate a surface wave packet on the surface. The reflectors are periodic arrays of either metal strips or grooves and reflect when their period is equal to half the SAW wavelength and there is corresponding increase in the array transmission loss. With a large number of strips or grooves, the array reflection coefficient can be very close to unity. For YZCY-cut Z-propagatingD lithium niobate which has an impedance discontinuity of 1.2%, 300 metallic strips are required in the array for a reflection coefficient of 98%. The resonator can give very high Q factors, up to 20,000, giving good stability. Furthermore, highly stable c. w. sources with frequencies up to about 2 GHz can be obtained by using SAW resonators. In this thesis, it will be given an analysis and synthesis procedure using transmission line model for the reflectors. The basic resonator structure is illustrated in Figure 3. Grooved array reflector substrate Figure 3. Two-port surface acoustic wave resonator CXIDThe applicability of surface wave devices to practical electronic systems is basically determined by the centre frequencies, bandwidths and delays obtainable. The upper limit for the centre frequency is determined by fabrication techniques, and current lithography is about 1.5 GHz. At low frequencies SAW devices become more bulky and expensive and other technologies become more suitable, for example bulk acoustic wave resonators for bandpass filters or digital techniques for signal processing. Consequent 1 y-, SAW devices are not normally used below a few MHz. In most applications this frequency range implies that the devices are used in the I. F. section of ' the system and this has the important consequence that low insertion loss is not generally a priority. For example, bandpass filters have typically 15 to 30 dB loss, and this is acceptable for many applications. Bandwidths generally range from a minimum of about lOO kHz to a maximum of about 50% of the centre frequency.