50 results about "Surface acoustic wave oscillators" patented technology

A surface acoustic wave resonator includes: an IDT which is disposed on a quartz substrate with Euler angles of (−1°≦φ≦1°, 117°≦θ≦142°, 42.79°≦|ψ|≦49.57°, which is made of Al or alloy including Al as a main component and which excites a surface acoustic wave in an upper mode of a stop band; and an inter-electrode-finger groove which is formed by recessing the quartz substrate between electrode fingers which form the IDT. Here, the following expression is satisfied:

0.01λ≦G  (1),

where λ represents a wavelength of the surface acoustic wave and G represents a depth of the inter-electrode-finger groove. The depth G of the inter-electrode-finger groove and a line occupancy η of the IDT satisfy the following expression:

and a number of pairs N of the electrode fingers in the IDT is in the range of the following expression:

160≦N≦220  (19).

A surface acoustic wave resonator has a quartz crystal substrate having Euler angles of (φ=0°, 110°≦θ≦150°, 88°≦ψ≦92°) and an IDT having a plurality of electrode fingers disposed on the quartz crystal substrate, and using a surface acoustic wave as an excitation wave, a plurality of grooves arranged in a propagation direction of the surface acoustic wave to form stripes is disposed on the quartz crystal substrate, and the electrode fingers are disposed one of between the grooves and inside the grooves.

A surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer (IDT) that includes electrode fingers exciting a surface acoustic wave on the piezoelectric substrate, a first region at a center of the IDT, and a second region and a third region at opposite sides of the IDT. In the IDT, a line occupation rate at which an electromechanical coupling coefficient becomes a maximum is different from the line occupation rate at which reflection of the surface acoustic wave becomes a maximum.

It is possible to reduce the size of a surface acoustic wave (SAW) resonator by enhancing a Q value. In a SAW resonator in which an IDT having electrode fingers for exciting SAW is disposed on a crystal substrate, the IDT includes a first region disposed at the center of the IDT and a second region and a third region disposed on both sides of the first region. A frequency is fixed in the first region and a portion in which a frequency gradually decreases as it approaches an edge of the IDT is disposed in the second region and the third region. When the frequency of the first region is Fa, the frequency at an edge of the second region is Fb_M, and the frequency at an edge of the third region is Fc_N, the variations in frequency are in the ranges of 0.9815<Fb_M/Fa<0.9953 and 0.9815<Fc_N/Fa<0.9953, respectively.

The invention relates to an ultralow phase noise reference signal generating device for a frequency synthesizer. The reference signal generating device comprises a crystal oscillator, a first phase locked loop and a second phase locked loop which are in sequential connection. The first phase locked loop comprises a first phase discriminator, a first loop filter and a voltage-controlled crystal oscillator which are in sequential connection, wherein the voltage-controlled crystal oscillator is connected with a feedback input end of the first phase discriminator. The second phase locked loop comprises a second phase discriminator, a second loop filter and a voltage-controlled surface acoustic wave oscillator which are in sequential connection, wherein the voltage-controlled surface acoustic wave oscillator is connected with a feedback input end of the second phase discriminator. Phase noises of reference signals generated by the ultralow phase noise reference signal generating device are optimal values at different frequency deviation positions of each oscillator, and the reference signal at each frequency deviation position can acquire the optimal phase noise.

The invention relates to an icing sensor based on a surface acoustic wave oscillator. The icing sensor comprises a surface acoustic wave device and an oscillation circuit (11), and further comprises apackaging tube shell (6) and a water permeable film (7), wherein the exterior of the surface acoustic wave device is packaged by the packaging tube shell (6), the water permeable film (7) is arrangedat an opening of the packaging tube shell (6), a surface of the surface acoustic wave oscillator is covered with a SiO2 protective thin layer (2), the surface acoustic wave device outputs an electricsignal with the changed oscillation frequency to the oscillation circuit (11), and the oscillation circuit (11) detects abrupt change of the oscillation frequency of the electric signal and outputs the oscillation frequency to realize icing early warning and monitoring. The icing sensor is advantaged in that the icing sensor has high detection sensitivity and good temperature stability, and can timely warn freezing, so the surface acoustic wave technology is easy to implement.

A frequency adjustable surface acoustic wave oscillator uses circuitry in which the phase relationship between the corresponding input and output signals and the voltage applied to or received by transducer fingers is controlled in such a manner that the frequency of the surface acoustic wave oscillator is arbitrarily controlled over a wide range by digital means. This provides an oscillator that exhibits a wide tunable frequency range while providing low phase noise.

A module for a surface acoustic wave oscillator includes a substrate having a top surface, a bottom surface and peripheral side faces. Several castellations are located about the outer peripheral side faces thereof. The castellations form an electrical connection between the top and bottom surfaces of the substrate. Connection pads are mounted on the top surface and are adapted for connection to the castellations. An oscillator circuit and a surface acoustic wave device are mounted on the top surface and connected to the connection pads. A cover is mounted over the substrate and has at least one tab adapted to be fitted within a respective one of the castellations. The overall module with the cover has a dimension of approximately 5 mm in width, 7 mm in length, and 2.7 mm in height.

The invention discloses an application circuit of a surface acoustic wave transducer. The application circuit comprises a first surface acoustic wave oscillator circuit, a second surface acoustic wave oscillator circuit, a mixer circuit and an LC passive low-pass filter circuit, wherein the output end of the first surface acoustic wave oscillator circuit and the output end of the second surface acoustic wave oscillator circuit are connected with the input end of the mixer circuit respectively, and the output end of the mixer circuit is connected with the input end of the LC passive low-pass filter circuit. According to the application circuit, a three-point capacitive negative feedback element is adopted as a frequency selection and feedback network, the feedback voltage of the capacitive negative feedback element is tapped from the two ends of a capacitor, higher harmonics can be effectively filtered out with small impedance, and stable waveform output is achieved; a high-frequency low-power tube amplifying circuit is a bias-emitter common-collector amplifying circuit, persistent oscillation is achieved, and therefore oscillation signals are more stable; two surface acoustic wave oscillators form a two-channel structure, interference caused by the external environment is avoided, and high-precision measurement of physical quantities to be measured is achieved.

It is possible to reduce the size of a surface acoustic wave resonator by enhancing the Q value. In a surface acoustic wave resonator in which an IDT having electrode fingers for exciting surface acoustic waves is formed on a crystal substrate, a line occupying ratio is defined as a value obtained by dividing the width of one electrode finger by the distance between the center lines of the gaps between one electrode finger and the electrode fingers adjacent to both sides thereof, and the IDT includes a region formed by gradually changing the line occupying ratio from the center to both edges so that the frequency gradually becomes lower from the center to both edges than the frequency at the center of the IDT.

The invention discloses a low-phase noise reference source. The low-phase noise reference source includes a phase-locked 100MHz signal source, a first frequency multiplier, a first mixer, a first loop filter and an ultra-high frequency voltage controlled surface acoustic wave oscillator; the first frequency multiplier performs frequency multiplication on stable 100MHz signals generated by the phase-locked 100MHz signal source so as to generate ultra-high frequency signals the frequency of which is same with the that of the output signals of the ultra-high frequency voltage controlled surface acoustic wave oscillator; the first mixer performs phase discrimination on the ultra-high frequency signals generated by the first frequency multiplier and signals outputted by the auxiliary path signal output end of the ultra-high frequency voltage controlled surface acoustic wave oscillator so as to generate first phase discrimination voltage; the first loop filter filters the first phase discrimination voltage so as to generate first voltage controlled voltage; and the ultra-high frequency voltage controlled surface acoustic wave oscillator outputs stable ultra-high frequency signals through a main path signal output end according to the control of the first voltage controlled voltage, wherein the stable ultra-high frequency signals are adopted as the output signals of the low-phase noise reference source. According to the low-phase noise reference source of the invention, the phase noise index of the reference source on higher frequencies can be improved.