Abstract: A HACT device employing a thin-film overlay of a more strongly piezoelectric material can operate as a delay line and as a tapped delay line, or transversal filter, while requiring less total power for the SAW clock signal. The increased electrical potential per unit total SAW power thus realized facilitates coupling between the total SAW energy and the mobile charge carriers. Some materials systems, such as a GaAs substrate and a ZnO thin-film overlay, will require an intervening thin-film dielectric layer in between the HACT substrate and epitaxial layers and the thin-film piezoelectric overlay. This may be necessitated by chemical, semiconductor device processing, or adhesion incompatibilities between the substrate material and the thin-film overlay material.

Abstract: A convolver includes first and second buried channels, with each of the channels comprised of a piezoelectric semiconductor. The input of one channel is associated with the output of the other channel. An acoustic transducer is positioned adjacent each input for generating an acoustic wave which propagates through the associated channels and thereby transports charge from the input to the output thereof. A non-destructive sensing array overlies the channels and samples the charge transported thereunder. The array includes an assembly for summing the sampled charge and for generating a product. An electrode is operably associated with the summing assembly for integrating the products and generating a convolution signal.

Abstract: A HACT device employing a thin-film overlay of a more strongly piezoelectric material can operate as a delay line and as a tapped delay line, or transversal filter, while requiring less total power for the SAW clock signal. The increased electrical potential per unit total SAW power thus realized facilitates coupling between the total SAW energy and the mobile charge carriers. Some materials systems, such as a GaAs substrate and a ZnO thin-film overlay, will require an intervening thin-film dielectric layer in between the HACT substrate and epitaxial layers and the thin-film piezoelectric overlay. This may be necessitated by chemical, semiconductor device processing, or adhesion incompatibilities between the substrate material and the thin-film overlay material.

Abstract: An acoustic transducer for an acoustic wave device which includes an acoustic wave propagating substrate, the transducer adapted to couple to an electrical load and/or source. The transducer includes at least a pair of comb electrodes formed on the substrate. It includes apparatus for applying an electrical load and/or source across the pair of comb electrodes. The first of the combs has a plurality of electrode fingers. The second comb has at least one electrode finger. The widths of the electrode fingers are the same. Gaps of at least two different widths are disposed between the electrodes.

Abstract: An ACT (acoustic charge transport) filter comprises a plurality of SAW (surface acoustic wave) transducers and an interleaved filter bank coupled on either transversal side of the SAW transducer. Each interleaved filter bank comprises two filters, and the electrodes of the two filters are interleaved. Isolation between the interleaved electrodes is supplied by a meadering ground. The electrodes are apodized to facilitate weighted sampling of the delayed signal. Multiple frequency characteristics may be extracted from a single ACT filter by cascading the SAW transducer/interleaved filter bank combinations. Weighted sampling of the delayed signal may also be accomplished through weighted withdrawal of the ACT filter.

Abstract: A bipolar injector structure, similar to a common-base amplifier circuit, is described for use as a unidirectional injector of charge for a charge-transfer device input circuit. This injector structure acts to reduce the input impedance of such devices. A plurality of bipolar injector structures may be implemented on a single ACT device channel, and electrically connected in parallel, to effect a further reduction of input impedance and a further increase in device dynamic range. By employing an input contact structure which allows charge to be injected at more than one point along the length of the channel, without perturbing charge which was injected at some earlier time, a means for forming a transversal filter function can be realized at the input contact structure in addition to that which is achieved at the output contact structure, thus permitting improved ACT device selectivity when operated as a filter.

Abstract: A piezoelectric semiconductor device for greatly increasing the linear channel length and storage capacity of an acoustic charge transport (ACT) device. Synchronized surface acoustic wave devices are aligned approximately orthogonally to each other so that in an angular portion of the channel, the charge packets of an input signal are bent at approximately a 45.degree. angle. As a result, channel length and therefore storage capacity of the channel and ACT device are greatly increased. One embodiment is a 45.degree. angle spiral channel. Another embodiment is a serpentine channel with 45.degree. angle bends.

Abstract: A HACT device employing a thin-film overlay of a more strongly piezoelectric material can operate as a delay line and as a tapped delay line, or transversal filter, while requiring less total power for the SAW clock signal. The increased electrical potential per unit total SAW power thus realized facilitates coupling between the total SAW energy and the mobile charge carriers. Some materials systems, such as a GaAs substrate and a ZnO thin-film overlay, will require an intervening thin-film dielectric layer in between the HACT substrate and epitaxial layers and the thin-film piezoelectric overlay. This may be necessitated by chemical, semiconductor device processing, or adhesion incompatibilities between the substrate material and the thin-film overlay material.

Abstract: An acoustic charge transport device (ACT) alters the intersection of an associated surface acoustic wave (SAW) electric potential with the static depletion potential and the input contact potential to correct the timing variations inherent in conventional ACT devices. The ACT device incorporates a pair of correcting electrodes secured to the ACT channel on either side of an input electrode. The electrodes vary the depth of the electric potential of the SAW which ensures sampling of the input signals at consistent times.

Abstract: A notch filter for reducing clock signal feedthrough effects in an acoustic charge transport (ACT) device. This notch filter is included on the same substrate as an ACT device. This notch filter may be employed to remove clock signals which have greater voltage than the data signals in an ACT device. This notch filter may be employed either at the input or the output of the ACT device. The notch filter includes a bridge connection of surface acoustic wave transducers and RC networks on opposite sides of the bridge configuration. Each side of the bridge is balanced so that at the notch filter frequency, the voltage output by each side of the bridge is one-half of the input voltage and in phase. These voltages produced by each half of the bridge are differenced and a zero output voltage is produced at approximately a notch or center frequency.

Abstract: A HACT device employing a thin-film overlay of a more strongly piezoelectric material can operate as a delay line and as a tapped delay line, or transversal filter, while requiring less total power for the SAW clock signal. The increased electrical potential per unit total SAW power thus realized facilitates coupling between the total SAW energy and the mobile charge carriers. Some materials systems, such as a GaAs substrate and a ZnO thin-film overlay, will require an intervening thin-film dielectric layer in between the HACT substrate and epitaxial layers and the thin-film piezoelectric overlay. This may be necessitated by chemical, semiconductor device processing, or adhesion incompatibilities between the substrate material and the thin-film overlay material.