Abstract: A circuit for generating a succession of fast rising voltage pulses comprises an inductor connected between first and second circuit nodes, a step recovery diode connected between a reference potential level and the first circuit node, and a current switch having a first state in which it conducts current in one direction with respect to the second circuit node and a second state in which it conducts current in the opposite direction with respect to the second circuit node. An oscillator is connected to the current switch for alternately and repeatedly placing the current switch in its first state and its second state. Preferably, the oscillator comprises a SAW resonator having a high Q and a parallel LC tank circuit having a low Q, connected in a closed positive feedback loop.

Abstract: A surface acoustic wave (SAW) device provides a phase shift and a first predetermined phase shift variation as a function of temperature. A passive network including a passive, reactive component is thermally and electrically coupled to the SAW device. An electrical characteristic of the component has a predetermined variation as a function of the temperature of the reactive component which provides the network with a second, predetermined phase variation as a function of temperature to compensate for the first predetermined phase variation as a function of temperature provided from the surface acoustic wave device. With this arrangement, the phase shift provided from the surface acoustic wave device is substantially invariant with temperature.

Abstract: Compensation for the effects of environmentally caused changes and aging on piezoelectric acoustic wave devices is electrically provided by the application of a signal, such as a DC bias voltage, to the finger elements of an interdigital transducer formed on the surface of the acoustic wave device. This produces very large field concentrations at the finger edges which act to magnify the electric field and accordingly the electroacoustic effect which alters the acoustic velocity of surface acoustic waves, shallow bulk acoustic waves and reflected bulk acoustic waves propagating in a piezoelectric substrate between input and output interdigital transducers.

Abstract: An surface acoustic wave coupling element is used having one output electrode (11d) and at least two input electrodes (11b, 11c) disposed at different distances or at different phase positions with respect to the output electrode, the input and output electrodes being arranged on one surface. The output electrodes of the element are connected to variable gain amplifiers through a power divider, the variable gain amplifiers receiving two gain control inputs. The output sides of these amplifiers (15, 16) are respectively connected to the input electrodes of said element. The variable frequency oscillator of this construction can be made much smaller than the prior art and can be effectively used as the high frequency oscillator in VHF and UHF bands.

Abstract: An oscillator including an active device (38), a surface acoustic wave resonator (40) connected in a feedback relationship to the active device and an impedance matching circuit is disclosed. The impedance matching circuit in one arrangement is an output impedance matching circuit including an inductor (46) connected in the feedback loop to the output of the active device. In another arrangement, the impedance matching network is an input impedance matching network including an inductor (42) connected in the feedback loop to the input of the active device. In another arrangement of the invention, a varactor diode (60) is connected in the feedback loop and is controlled by a reverse voltage which changes the capacitance of the diode, adjusting the frequency of the oscillator.

Abstract: A voltage-controlled oscillator includes an amplifier having two emitter-coupled differential amplifier stages, and in whose feedback network, connected in series, are a 3dB-90.degree. coupler and a surface-wave transmission line. Two variable capacitance diodes are connected to the two terminals of the coupler that are not used as input or output terminals, and a frequency control voltage is applied to both diodes. The oscillator is particularly well-suited for the transmission of digital signals with transmission speeds of over 100 Mbit/s.

Abstract: Signal processing by means of a system comprising an elastic wave device, invariant with the temperature.The input signal S.sub.e is written into a memory at the timing of a fixed clock h.sub.E and read at the timing of a clock H.sub.L supplied by a slaved generator, which also supplies the signals particularly for modulation to an interface circuit. The signal is applied to an elastic wave device which supplies a processed signal S.sub.3 applied to a second interface circuit and to a second memory. The slaved generator also supplies the demodulation signals to the second interface circuit and the writing clock signals H.sub.E of the second memory, which is read at the fixed clock timing h.sub.L. The slaved generator comprises a basic driver formed by a surface elastic wave oscillator constructed with the same substrate as that of the elastic wave processing device.

Abstract: The inherent temperature instability of surface acoustic wave (SAW) clock oscillators is improved by the use of a thermometer oscillator circuit that senses temperature changes in the SAW substrate. The thermometer oscillator is used in combination with a calibrated programmable read only memory and a logic circuit and provides frequency corrections to the clock oscillator. The basic device is an oscillator clock circuit using a SAW substrate having a delay path orientation with good temperature stability. A second oscillator, the thermometer oscillator circuit, and the electronic compensation scheme are added in order to produce minimum temperature coefficient of delay over all temperatures in the range of interest. The thermometer oscillator delay path utilizes a high temperature coefficient of delay orientation of the same SAW substrate and at an appropriate angle to the clock oscillator delay path orientation.

Abstract: An elastic surface wave recursive filter comprising: at least one delay line formed by two elastic surface wave transducers, such line being looped on itself externally by an amplifier, a means for introducing an elastic surface wave into such line, such means being connected to an input of the filter, and a third transducer having the form of a transversal filter, the transducer being coupled to said line and connected to an output of the filter. The transfer function of the filter is the form P(z)/Q(z), the numerator and the denominator being independant.

Abstract: The volume magnetostatic wave device comprises a unidirectional-radiation transducer composed of equidistant microstrips connected to a polyphase transformer and coupled to a ferrimagnetic wafer which is subjected to a polarizing magnetic field.

Abstract: A surface acoustic wave resonator formed on a semiconductive piezoelectric substrate (9) has arrays (10, 11) of reflector elements forming rectifying junctions with the substrate, a voltage is impressed between the arrays and related ohmic ground contacts (12, 13) for controlling the carrier concentration beneath the arrays so as to vary the acoustic velocity therebeneath, thereby to tune the resonator. The resonator may include two acoustoelectric transducers (16, 17) for connection with an amplifier in an oscillator loop, or may have but a single acoustoelectric transducer (20) for interconnection between the elements of an oscillator circuit (21).

Abstract: Acoustic wave devices employing shallow bulk acoustic waves rather than surface acoustic waves, to provide higher frequencies of operation and other significant advantages, such as less susceptibility to aging and less sensitivity to surface contamination. In each embodiment of the invention, a transmitting transducer and a receiving transducer are oriented on the surface of an anisotropic piezoelectric crystal to achieve substantial coupling of shallow bulk acoustic waves and essentially zero coupling of surface acoustic waves. In one embodiment of the invention, various types of grating filters utilize shallow bulk acoustic waves, and a set of parallel mechanical or electrical discontinuities at or near the surface of the crystal provide reflection of acoustic energy at a frequency determined by the spacing of the discontinuities. Uniformly spaced gratings provide bandpass filter operation, and gratings with graduated spacings provide for frequency compression or expansion.

Abstract: A unidirectional magnetometer comprising at least two magnetostatic wave oscillators with resonators or delay lines, made in two portions in a magnetic material layer respectively subject to the field to be measured and to given magnetic fields of the same direction, but of opposite sense and adjacent intensities.

Abstract: A surface acoustic wave device in which an X-cut LiTaO.sub.3 single crystal substrate has its one major surface coated with a SiO.sub.2 film and the direction of propagation of surface acoustic waves is selected between 80.degree. and 180.degree. measured from the Y-axis toward the Z-axis. The surface acoustic wave devices in accordance with the present invention has an extremely low temperature coefficient change and a high electro-mechanical coupling coefficient, exhibits a higher degree of both short- and long-term stability, and can suppress the generation of unwanted waves to a minimum or negligible degree.

Abstract: An arrangement for temperature compensating transducers including two elastic surface wave oscillators whose frequencies are mixed to produce an output frequency that is a function of a parameter to be measured such as force, pressure or acceleration. A delay element such as a transmission line having a delay that is a function of temperature is inserted into the loop of at least one of the oscillators to balance oscillator frequency deviations resulting from temperature changes.

Abstract: The interfering resonances of transverse modes are moade to occur far from the fundamental resonant frequency in a surface acoustic wave (SAW) resonator by connecting a plurality of SAW sub-devices in parallel. The frequency response of this parallel combination is essentially undistorted. Interfering spurious resonances caused by the transverse modes become inconsequential. These devices have a substantially higher power handling capability as compared to conventional resonators with comparable Q. This capability reduces the phase noise of oscillators stabilized by these resonators.

Abstract: Mode locked surface acoustic wave oscillators, configured as comb spectrum generators, are stabilized by means of a variable phase in the closed, oscillation loop, the phase being controlled in response to deviations of the low, pulse repetition frequency from a design reference PRF. The variable phase may be provided by a variable phase device inserted in the oscillatory loop, such as varactor-tuned lumped element delay lines or 90.degree. hybrids, or other devices. Or, the variable phase may be provided by a voltage tunable surface acoustic wave device used as the basic oscillator SAW delay line.

Abstract: Microwave oscillator using magnetostatic surface or bulk waves which can be transmitted in a thin layer of magnetic material having two cavity resonators with coupled gratings of different equivalent lengths in such a way that the first is multimode and the second monomode in the reflection pass band of the gratings, the cavities being arranged in such a way that the second filters the modes transmitted in the first. Microwave signals are applied to one of the two cavities and the resonated waves are collected in the second cavity.

Abstract: Apparatus for providing a plurality of filtered outputs is described incorporating a substrate suitable for propagating surface acoustic waves having an input transducer, a first plurality of spaced-apart taps coupled together, a second plurality of spaced-apart taps coupled together where at least two of the second plurality of taps are positioned in spaces between the first plurality of taps.The invention overcomes the problem of providing separate substrate surface area for each plurality of taps coupled together.

Abstract: A surface acoustic wave sensor system in which a predetermined level of coupling between two surface acoustic wave arrays is intentionally provided in order to couple radio frequency energy from one into the other and thereby, in cooperative effect with attendant oscillator circuits and a filter, results in the development of a difference frequency which is a function of the sensed condition.

Abstract: An oscillator including two magnetostatic wave delay lines of different lengths formed on the surface of a magnetic material, one of whose ends is common and made by a first microstrip coupler, each of the other ends being made of a second and a third microstrip couplers respectively. The two lines are looped by means of a single amplifier. By selecting the two lengths, it is possible to obtain the desired interval between modes in such a way that there is a single oscillation mode comprised in the pass-band of the strips, in a pre-determined tuning band. This oscillator operates in the microwave range.

Abstract: An acoustic wave device comprises a substrate carrying two or more acoustic components aligned in different directions and electrically connected together in parallel. The phase slope of the acoustic components are similar but their temperature coefficients of delay are different whereby their resultant frequency response is compensated over a useful temperature range. The acoustic components may be delay line employing surface waves or surface skimming bulk waves, or one or two port resonators using surface waves.

Abstract: Frequency modulators for use in microwave link transmission systems include acoustic surface wave (ASW) oscillators. Each frequency modulator comprises two voltage control quadripole ASW oscillators. Control inputs of the two ASW oscillators receive modulation signal in opposite phase. Outputs of ASW oscillators are mixed in a mixer for delivering an IF signal. Thus frequency deviation is larger than in a conventional arrangement. Moreover, surface wave oscillators make it possible to directly insert a service channel signal in a microwave link repeater, without demodulation and modulation operations.

Abstract: The microwave oscillator is formed by a free oscillator 1 coupled with two surface or volume acoustic wave delay lines 9 and 10 connected in series or in parallel and operating by reflection. The first line imposes a delay 2.tau..sub.1, corresponding to one reciprocation, which is a multiple of the delay 2.tau..sub.2 imposed by the second line, and a=.tau.1/.tau.2 is preferably equal to 2 or 3. Application to oscillators operating at ultra-high frequencies, particularly in the L-band.

Abstract: A transmitting section includes an oscillator which has a surface acoustic wave device of which the frequency characteristic varies responding to the temperature of a base plate thereof, the oscillator generating an oscillation output of a frequency corresponding to the frequency characteristic and an antenna for transmitting the oscillation output. A receiving section includes a receiving antenna, a means for detecting the output of the receiving antenna, and a signal processing circuit for processing the output of the detecting means to generate at least one of the temperature display and control signals of the base plate of the surface acoustic wave device.

Abstract: A surface acoustic resonator including an interdigital transducer configured to generate acoustic waves at at least one harmonic frequency, and a pair of reflection gratings capable of essentially total reflection of the acoustic waves in both fundamental and harmonic modes of operation. One-port and two-port resonators are disclosed, capable of operation at fundamental and harmonic frequencies, to provide a higher frequency of operation without correspondingly higher resolution requirements for manufacturing processes. For single-mode operation at higher frequencies, the interdigital transducer and reflection gratings have different fundamental frequencies, and utilize harmonics of different order but the same actual frequency, such that the resonator functions at a single frequency, which may be, for example, the third harmonic with respect to the transducer fundamental frequency, and the second harmonic with respect to the reflection grating-fundamental frequency.

Abstract: An oscillation control circuit in which the output of an unstabilized oscillator is controlled using a bulk acoustic wave resonator. The circuit includes a high and low frequency loop with the power output of the oscillator being divided and supplied along respective paths to the high and low frequency portions of the loop. The high frequency portion of the loop, which includes the BAW resonator, operates at the output frequency f.sub.0, which is equal to the sum of the oscillator frequency f.sub.1 and the frequency f.sub.2 of the low frequency portion of the loop. A first mixer receives the frequencies f.sub.0 and f.sub.1 and produces an output f.sub.2 in the low frequency portion of the loop, while a second mixer receives the frequencies f.sub.1 and f.sub.2 and produces an output f.sub.0 in the high frequency portion of the loop. In this way, as the oscillator output frequency f.sub.1 varies, the frequency f.sub.

Abstract: An electrically controlled surface acoustic wave (SAW) delay unit includes a piezoelectric and semiconductive substrate having a segmented rectifying contact disposed on the surface of an interaction region between launching and detecting transducers, with a controllable voltage applied to the rectifying contact, thereby to vary the concentration of carriers in the semiconductive material, so as to commensurately alter the velocity of surface acoustic waves in the module. The segmented contact provides significant increase in the achievable variation in velocity, and therefore in phase as well. An oscillator configuration includes such a module with an amplifier and other circuit elements formed integrally therewith in a monolithic fashion.

Abstract: A generator for variable frequency submillimeter waves launches surface astic waves in piezoelectric material for generation of an associated acousto-electrical field. An electron beam is acted upon by the acousto-electrical field in a manner simulating the effect of an etched grating, resulting in an output frequency which may be varied by the variation of the acoustic wave frequency, or the velocity of the electron beam.

Abstract: A plurality of parallel-connected surface acoustic wave (SAW) resonators, having different oscillation frequencies and different turnover temperatures, are connected to an active element containing circuit to form a SAW oscillator. The oscillator frequency deviation due to temperature is kept within a small allowable range .DELTA. fa by satisfying the following formulas:f.sub.H -f.sub.L .ltoreq..DELTA.faT.sub.p1 <T.sub.p2. . .<T.sub.pnwheref.sub.H : a maximum frequency among those frequencies of a plurality of SAW resonators connected to the active element-containing circuit which are produced at turnover temperatures on a temperature curve;f.sub.L : a minimum frequency among those of the plurality of SAW resonators; andT.sub.p1 to T.sub.p2 : the turnover temperatures corresponding to the individual SAW resonators.

Abstract: A thin-film integrated circuit with tank circuit characteristics may comprise a surface acoustic wave transducer with appropriate geometry. A preferred embodiment of such integrated circuit includes, in addition to the surface acoustic wave transducer, surface acoustic wave reflecting means located adjacent the transducer, and preferably on opposite sides thereof. The reflecting means may include a pair of reflectors and be proportioned so that the device exhibits a single resonant-anti-resonant frequency pair, such as a single tank circuit. Alternatively, the reflectors may be proportioned such that the device exhibits multiple resonant-anti-resonant frequency pairs. The operating frequency may be as high as hundreds of megahertz to one gigahertz.Applications of the thin-film integrated circuit to thin-film filters and oscillators are also disclosed.

Abstract: Jamming arrangements comprising an oscillator including a number of circuits each comprising a surface acoustic wave filter feeding an amplifier responsive only to signals above a predetermined threshold level, the filter characteristics being chosen so that each circuit is responsive to a different range of frequencies, the circuits being connected mutually in parallel and a switch being provided via which the output circuits of the terminals are coupled to the input terminals to define a feedback loop when the switch is closed, the arrangement being such that when the switch is closed and a signal to be jammed is injected into the loop at a frequency within the pass band of at least one of the filters so as to produce a signal which is fed to its associated amplifier above the threshold, oscillation is maintained around the loop at the frequency of the signal to be jammed.

Abstract: An acoustic periodic structure for slow wave propagation and filtering having a corrugated surface with traction-free boundaries which can support a horizontally polarized shear surface wave that travels much slower than the bulk shear wave velocity and that exhibits an upper cut-off frequency. Electrodes are located on the tops of the teeth forming the corrugated surface and alternate electrodes are excited out of phase, the distribution of the excitation voltage phases determining the particular mode of resonance.

Abstract: The invention relates to elastic surface wave oscillators using a feedback loop formed by a filter consisting of two interdigitated comb transducers. More particularly, the invention relates to a stable oscillator having a low harmonic content wherein the electrical oscillation energy is extracted by means of an auxiliary interdigitated transducer receiving a fraction of the vibratory energy exchanged in the feedback loop.

Abstract: An acoustic wave discriminator comprises an acoustic wave delay line having an input transducer and a plurality of output transducer separately connectable to a phase sensitive detector. This detector measures the phase difference between input and output transducers and provides an output for controlling the frequency of a voltage controlled oscillator. A plurality of different frequencies of the oscillator is obtained by connecting different output transducers of the discriminator to the phase sensitive detector.

Abstract: A sensor developing a digital output in response to force induced deflection in which the deflection is of a beam formed to have, under stress, a surface undulate in both compression and tension. The signal is developed from piezoelectric transducers connected in a pair of oscillator circuits utilizing surface acoustic wave paths through, respectively, the tension and the compression portions of the beam surface. The frequencies of the oscillators are compared and the frequency difference resulting from beam deflection is sent as a signal to a counter to give a digital read out of the force causing the deflection. The beam is formed of steel and the piezoelectric surface for the surface waves and the interdigitated conductors forming the transducers are deposited by thin film techniques on the beam.

Abstract: An automatic frequency-hop controller for a surface acoustic wave (SAW) shesizer is used with a means for generating two chirp signals, one having a delay with respect to the other. It comprises a SAW device, adapted to receive the chirp signals. The SAW device comprises a substrate and a pair of sets of interdigitated electrodes, disposed on the surface of the substrate, one set at each end, the electrodes receiving the electrical chirp signals or corresponding impulse signals. Another set of interdigitated electrodes, which are output electrodes, are also disposed on the surface of the substrate, the electrodes of all sets being parallel. The output set of electrodes are so disposed as to receive the acoustic waves generated by the pair of sets of electrodes, and transduce them back to electrical signals.

Abstract: An oscillator uses a delay line in a feedback loop to determine its frequency of operation. As the loop is capable of sustaining oscillations at more than one frequency the desired frequency is generated by an auxiliary delay line and is gated into loop at the correct instant by gating circuitry C.

Abstract: A frequency synthesizer, for use with a means for generating two sequences of electrical pulses, one sequence having a delay with respect to the other, comprises a surface acoustic wave (SAW) device, adapted to receive one of the sequences of electrical pulses from the generating means. The SAW device comprises a substrate, on the surface of which is disposed a first set of interdigitated electrodes. The electrodes receive the electrical pulses and tranduce them to acoustic waves, which traverse the surface of the substrate. The lengths of the electrodes are configured as a function of m, where m is defined by the relation m = R.sup.n mod P, where P is a prime number, R is a primitive root of P, and 1.ltoreq.n.ltoreq.P-1. A second set of interdigitated electrodes, approximately N-1 in number, is also disposed on the surface of the substrate, the electrodes of the first and second sets being parallel.

Abstract: A mode-locked surface acoustic wave oscillator (MLSO) provides mode-locked, phase coherent RF signal pulses through a regenerative closed loop RF signal path which includes a surface acoustic wave (SAW) delay line having a piezoelectric substrate and a pair of signal transducers relatively disposed at a determined SAW propagation distance along a major surface thereof, an RF amplifier to provide in phase amplification of the RF pulse, and a signal expander circuit for providing an increase in the harmonic frequencies of the RF signal pulse and an increased RF pulse frequency bandwidth. The pulse repetition frequency is determined by the signal propagation time delay, provided primarily by the SAW delay line. The delay line transducers establish the center frequency of the RF signal pulse and the bandwidth of the regenerative loop limits the minimum obtainable RF pulse width.

Abstract: A multi-moded acoustic wave oscillator comprises an amplifier and feedback loop incorporating an acoustic wave delay line which may be a surface acoustic wave delay or bulk acoustic delay. Frequency of oscillation is changed in steps by taking different phased outputs from the delay line. This phase difference is achieved either by spacing surface acoustic wave transducers different distances on a substrate from an input transducer or by phase shift circuitry.

Abstract: An oscillator or similar device employing a frequency setting SAW element having a piezoelectric substrate and an arrangement of interdigital finger transducers mounted thereon. In one embodiment, two interdigital finger transducers provide surface acoustic wave launching and reception respectively and in another embodiment, two additional transducers form a part of a discriminator circuit. Phase detection either between the electrical connections of the launching and receiving transducers or through the discriminator arrangement generates a feedback control signal which is applied across the ends of the substrate as a stress-controlling signal in a manner to compensate for temperature and other environmental factors which otherwise change the frequency of oscillation.

Abstract: An oscillator for operation in the frequency range from about 2 GHz to at least 18 GHz using a magnetostatic surface wave delay line as a frequency control element in a feedback loop connected around an amplifier. The oscillator is tunable by varying the magnetic field intensity at the magnetostatic surface wave propagating medium and by varying the distance between input and output rf couplers along the propagation surface.

Abstract: An acoustic surface wave oscillator is constructed from a semiconductor-piezoelectric acoustic surface wave amplifier by providing appropriate perturbations at the piezoelectric boundary. The perturbations cause Bragg order reflections that maintain acoustic-wave oscillation under certain conditions of gain and feedback.

Abstract: The present invention relates to surface elastic wave programmable oscillators. The oscillator in accordance with the invention comprises an amplifier and a feedback loop comprising a selective surface wave transmission system which offers N possibilities of energy exchange between a transducer array with curved teeth, and a set of auxiliary transducers arranged in a fantail fashion.

Abstract: Disclosed apparatus compensates for the parabolic temperature induced frequency drift characteristic of a surface acoustic wave tuned oscillator. The apparatus includes a pair of varactor diodes and a temperature sensitive voltage supply. The diodes are series connected and coupled in circuit with the oscillator to affect the frequency thereof. The voltage supply connects to the common connection of the diodes, for producing control voltages thereat.Each varactor diode is chosen to have a .delta. > 1; and the control voltage varies linearly with temperature. This results in a varactor diode capacitance versus temperature characteristic which is a continuous, true parabolic function providing precise compensation for the thermal drift of oscillator frequency.

Abstract: A temperature stable surface acoustic wave device utilizing reflective gratings in a material such as Y-cut quartz having two propagation directions in which the temperature coefficients of delay are of opposite sign, the gratings reflecting the Rayleigh waves in the two propagation directions along suitable path lengths to provide a total linear zero temperature coefficient of delay. A temperature stable oscillator is formed by providing an amplifier in a feedback path from the output transducer to the input transducer of the surface acoustic wave device.

Abstract: A variable frequency VHF or UHF band oscillator is disclosed. Principal control over the precise location and stability of the frequency of oscillation is provided by a surface wave delay line in the regenerative feedback path of a broadband amplifier. The surface wave delay line is capable of passing substantial energy within each of a plurality of very narrow passbands. Controls are provided for ensuring that at any given time the circuit can oscillate only at the resonant frequency of one of these passbands. Selection of the frequency of oscillation is in accordance with an externally applied digital frequency select signal.

Abstract: An oscillator in which the "tank circuit" or feedback element is a surface acoustic wave (SAW) bandpass filter (delay line). A modulating voltage is applied from end-to-end of the piezoelectric substrate material to provide an incremental change of physical length of the substrate as a function of the modulating voltage. Two sets of interleaved fingers along a surface face of the substrate provide an interdigital arrangement for launching (electrical to acoustic transition) and receiving (acoustic to electrical transition) the surface acoustic wave.

Abstract: A temperature compensated surface acoustic wave device having an SiO.sub.2 film layer upon a substrate of piezoelectric material. The positive temperature coefficient of delay of the piezoelectric substrate is counterbalanced by the negative temperature coefficient of the SiO.sub.2 layer. The thickness and shape of the SiO.sub.2 layer are chosen to give a zero first order temperature coefficient for the composite device. Lithium niobate and lithium tantalate are preferred piezoelectric materials for the substrate. A high degree of temperature stability is thereby obtained with coupling coefficients much greater than were previously obtained by prior temperature compensated surface acoustic wave devices.