United Technologies Corporation

Tektronix, Inc.

Thomas M Reeder

Thomas W Grudkowski

Anthony J DeMaria

Meyer Gilden

Gary K Montress

Donald E Cullen

An optical phase shifter comprises an optical waveguide of electro-optic material and an electrode structure associated with the waveguide for imposing an electrical field on the waveguide. The electrode structure comprises at least two groups of electrodes, each group having at least first and second electrodes between which the waveguide passes. The first electrode of one group and the second electrode of the other group are on opposite respective sides of the waveguide and are connected to respective input terminals for receiving an electrical signal. The second electrode of the one group is connected to the first electrode of the other group.

Electro-optic phase shifter with reduced input capacitance

Self-scanned piezoelectric delay line effective for time multiplexing system sampled physical parameters, subject to frequency mixing of the product signals from a clocked RF signal generator passing through a plurality of electrodes in the delay line, and the signals of voltage controlled oscillators driven by sensor detectors linked to the physical system.

Self-scanned time multiplexer with delay line

A monolithic surface acoustic wave (SAW) signal processor which combines the functions of acoustic wave interaction, nonlinear product mixing, and integration, together with rapid-scan readout capability, which may be used, for instance, in correlation of amplitude and/or phase coded signals of a duration order of magnitude larger than the total propagation delay time of the SAW device, includes launching transducers at opposite ends of an interaction region, and a plurality of interaction taps, each tap comprising a Schottky barrier field effect transistor (FET), the sources and drains of the FETs being connected in common, but each FET gate being isolated. For long code correlation of a phase shift keyed signal, a reference wave having the same carrier frequency and identical coding is launched contemporaneously therewith in a first, correlation step, a standing wave component of product mixing of the two waves being of like sign or sense at any tap where the two waves are properly in phase integrating over the total number of code chips of the waves to provide an integrated, stored charge manifestation of correlation on the isolated gate of the related tap, the taps being interrogated for an integrated indication of correlation at one of the taps by means of a pulse of width the same as the propagation delay of a single tap mixing with an extended carrier at each tap, a component of product mixing at a third frequency (sum or difference) as a consequence of enhanced mixer efficiency due to the stored charge at the correlating tap, providing an output indication of the fact of correlation and phase relationship between the two waves. Various surface acoustic wave transducer and tap structures, utilizations, and implementation techniques are discussed.

Monolithic isolated gate FET saw signal processor

Signals extracted from the taps of a surface acoustic wave (SAW) device, as a consequence of a single wave propogating therein or as a consequence of interaction between a pair of waves propagating therein, are processed by linearly-controlled nonlinear product mixing and/or amplifying devices, to provide output signals in a serial chain of chips of RF, the magnitude of chips being dependent upon unique, selected bias applied to corresponding ones of the devices. The devices may be diodes operating in a bias range to provide impedence greater than the capacitive reactance impedance of the taps to which they are attached, thereby providing a linear RF voltage to DC bias current characteristic, while at the same time providing a nonlinear DC voltage to DC current characteristic for RF product mixing (where used); or the devices may comprise transistors, either field effect or bipolar, with similar suitable bias considerations when linearly-controlled product mixing is desired. Applications, with or without output frequency isolation from input frequencies, include time division multiplexing of DC signals (such as transducer output signals), and transversal filtering, of the type useful in correlation or other wave or coded signal analysis.

Linear SAW signal processor

A surface acoustic wave signal processor having a plurality of taps, each connected to an external nonlinear device are arranged in pairs, each pair having its phase center aligned for interception of propagating waves at the same transversal distance from the launching thereof, the taps having configurations so that each tap in the pair receives signals at a phase which is inverted (180.degree. out of phase) with respect to corresponding signals received at the other tap of the pair, the product mixing output of the external nonlinear device for each tap being summed with the like output for the other tap in the pair, whereby all waves intercepted by the tap pair are cancelled at the product mixer outputs, along with certain of the components of product mixing having odd-ordered exponents. Disclosed configurations include tilted taps with co-propagating waves, longitudinally aligned taps with counter-propagating waves, and co-linear taps with plural channel, transversally displaced waves. Usage with internal mixing is also described.

Differential mixing surface acoustic wave signal processor

A surface acoustic wave signal processor comprises a piezoelectric substrate having acoustoelectric transducers disposed thereon in discrete channels which run along the direction of propagation of the substrate, there being a plurality of acoustoelectric transducers in each channel which are connected to related ones in adjacent channels, and a transducer in each channel which is electrically independent from related ones in adjacent channels, thereby providing a plurality of ports, each port having a transducer in each of the channels, the transducers of at least one of the ports being electrically interconnected and those of at least one of the ports being electrically independent. A variety of configurations and utilizations are disclosed.

Two-dimensional surface acoustic wave signal processor

A diaphragm formed in a substrate and having a piezoelectric surface includes a first surface acoustic wave (SAW) delay line disposed on said surface and connected in an oscillator circuit for a significant frequency sensitivity to surface strain of said diaphragm, and a second, similar oscillator with the SAW delay line thereof connected for a significant frequency sensitivity to surface strain of the diaphragm opposite in sense to that of the first oscillator, and a mixer for providing the difference in the frequencies of the two oscillators, whereby the overall sensitivity to strain is enhanced, while at the same time the sensitivity to temperature variations is reduced significantly through subtractive combination.

Differential surface acoustic wave transducer

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. An alternative embodiment of the MLSO includes a secondary loop which provides automatic generation of a synchronized trigger pulse having a pulse repetition frequency (PRF) derived from the RF signal pulse circulating in the regenerative loop. The synchronized trigger modulates the RF signal in the regenerative loop at a PRF equal to the reciprocal of the time delay of the SAW delay line, to further enhance the frequency mode-locked operation.

Mode-locked, surface acoustic wave oscillator

A surface acoustic wave (SAW) tapped delay line, including a piezoelectric substrate having a pair of signal launching transducers disposed thereon for providing surface acoustic waves in the substrate in response to electrical signals applied thereto, and including a plurality of transducer taps disposed in an interaction region of the substrate for providing a plurality of sensed electrical signals in response to the surface acoustic waves propagating through the interaction region, the plurality of sensed electrical signals including signals at the frequency of each of the acoustic waves, is combined with a plurality of nonlinear frequency mixers, each responsive to a corresponding one of the transducer taps, and each providing signal manifestations of the sum and difference frequency of the surface acoustic waves in a selected one of two phases which are displaced by 180.degree. with respect to each other, the combination of the SAW tapped delay line and plurality of selective phase nonlinear frequency mixers providing a programmable phase, nonlinear surface acoustic wave PSK encoder/correlator.

Nonlinear surface acoustic wave PSK encoder/correlator

A surface acoustic wave (SAW) tapped delay line, including a piezoelectric substrate having a pair of signal launching transducers disposed thereon for providing surface acoustic waves in the substrate in response to electrical signals applied thereto, and including a plurality of transducer taps disposed in an interaction region of the substrate for providing a plurality of sensed electrical signals in response to the surface acoustic waves propagating through the interaction region, the plurality of sensed electrical signals including signals at the frequency of each of the acoustic waves, is combined with a plurality of nonlinear frequency mixers, each responsive to a corresponding one of the transducer taps, and each providing signal manifestations of the sum and different frequencies of the surface acoustic waves in a selected one of two phases which are displaced by 180.degree. with respect to each other, and at signal amplitudes which are selectively adjustable to provide a desired transducer tap amplitude weighting. The selectively adjustable phase and amplitude of the nonlinear frequency mixer signal manifestations provide a programmable SAW delay line suitable for use as a programmable, amplitude and phase, general transversal filter having high programming speed and low power consumption.

Programmable, amplitude and phase, general transversal filter

A nonlinear delay line correlator and convolver is described which comprises a tapped, piezoelectric surface acoustic wave delay line and an array of series or parallel connected forward biased semiconductor diodes. An interdigital signal transducer is connected to each end of the delay line and voltages are applied to each transducer to generate contra-flowing acoustic strain waves which are radiated toward an interaction region comprising a plurality of equi-spaced weakly coupled interdigital transducers, each transducer being connected to one diode. Nonlinear signal mixing in the diode array is utilized to perform serial product convolution or correlation of the signal modulation applied at the two signal input transducers. Because of the large nonlinearity of semiconductor diodes, insertion loss is relatively low. One feature of the diode correlator is a novel dual acoustic beam transducer which permits two separate acoustic beams to be generated without interaction therebetween except at the transducer taps.

Diode coupled tapped acoustic delay line correlator and convolver

Surface acoustic waves are propagated across a thin, flexible diaphragm which is subjected to an applied external pressure. Since the wave velocity and path length vary with diaphragm deformation, the acoustic wave delay time is a function of the applied external pressure. Electroacoustic transducers are fabricated on opposite edges of the diaphragm for electronic excitation and detection of the surface acoustic wave. An electronic feedback path including the two transducers, the wave path, and an electronic amplifier oscillates at a frequency which is determined by the delay time required for acoustic wave propagation over the diaphragm path, and which decreases approximately linearly with applied external pressure. A second acoustic path called the reference path has a length equal to the first path and in the preferred embodiment contains a diaphragm which is subject to a different applied pressure. A second electronic feedback path composed of two transducers, the reference path and a second amplifier oscillates at a second frequency called the reference frequency. By applying a sample of the first and second oscillator voltages to a semiconductor mixer, a difference frequency output is obtained which is proportional to the differential pressure. The difference frequency output is approximately independent of temperature, and is easily converted to various digital codes by use of standard frequency counter circuits. If only one set of transducers is used, the device can also measure temperature in a digital manner. By adding a mass load to the center of the diaphragm, acceleration may be measured. Stress or strain measurements may also be made by bonding the diaphragms or only the transducers directly on the physical surface to be measured.

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Glastonbury, CT, United States of America

Thomas M Reeder