Abstract: A SAW detector has a SAW transducer 10 disposed on the surface of a piezoelectric substrate 12 which injects a SAW 20 in response to an RF input signal applied to line 14. A semiconductor charge transport region 30 comprising a charge transport channel 32 sandwiched between two charge confinement layers 34,36, is disposed above the substrate. A source electrode 40 provides electrons to the channel 32 and a drain electrode 42 removes electrons from the channel 32. The electric fields generated by the SAW 20 travel along the channel 32 and provide a forcing function to move the electrons from the source electrode to the drain electrode as a continuum, not in charge packets, thereby providing output current 48 on a line 49 indicative of the SAW 20 frequency.

Abstract: A heterostructure acoustic charge transport (HACT) device having a number of signal tap electrodes has revealed unexpected insensitivity to electrode spacing and unexpected sensitivity to electrode width. Spacing of one SAW wavelength between consecutive electrodes and an electrode width of .lambda./20 are preferred.

Abstract: An acoustic charge transport device having a number of signal tap electrodes has revealed unexpected insensitivity to electrode spacing and unexpected sensitivity to electrode width. Spacing of one-half SAW wavelength between consecutive electrodes and an electrode width of .lambda./20 are preferred for low frequency response.

Abstract: A simplified heterostructure charge transport device has a GaAs transport layer that is the top layer of the device, deposited on an (Al,Ga) As barrier layer for vertical confinement of charge packets. Confinement at the top surface is provided by pinning of the conduction band surface states.

Abstract: A novel heterostructure acoustic charge transport (HACT) device is capable of direct optical modulation. The device includes a transducer fabricated on a substrate structure that launches surface acoustic waves. A reflector is formed in the substrate structure at an end portion adjacent to the transducer for reflecting the surface acoustic waves. Also included is an electrode configured with the transport channel at an end thereof distal to the transducer for generating electrical signal equivalents of the propagating electrode charge. The device is characterized by a transport channel with an intrinsic vertical electrical potential such that electron-hole pairs created by incident electromagnetic radiation are separated from one another before recombination, with electrical charges therefrom provided to the surface acoustic waves.

Abstract: A novel heterojunction acoustic charge transport device includes a transducer fabricated on a GaAs/AlGaAs heterojunction material that launches surface acoustic waver (SAW) along a transport channel. The device is characterized by a photodiode configured adjacent to the channel on the substrate to receive a modulated optical beam. An electrical signal equivalent is provided to a Schottky electrode at the end of the transport channel modulating the charge propagated by the surface acoustic wave. The modulated signal is output at a distal end of the transport channel.

Abstract: An improved acoustic charge transport device having an acoustic wave passing through a piezoelectric semiconductor is improved by utilizing heterostructure Quantum-wells for confining charge packets.

Abstract: A large bandwidth, tapped delay line (TDL) surface acoustic wave (SAW) adaptive processor arrangement, for processing a plurality of array values employed as tap weights in the TDL device. The weight quantities may be real or complex. In the complex case, no phase quadrature combiner is required as a result of the technique of offsetting the real and imaginary delay lines, or offset launching of the frequency waveforms to be mixed.

Abstract: A signal processor for filtering unwanted narrowband noise from received wideband electrical signals also containing desired wideband noise is described. The signal processor includes means for partitioning the wideband received signal into a plurality of narrowband, noise-containing signals and for producing a plurality of narrowband output signals. The signal processor further includes means for monitoring each of the narrowband output signals and for reducing the voltage of any narrowband output signal when that signal exceeds a predetermined level. In the preferred embodiment, the monitoring means of the signal processor includes a plurality of voltage-regulating networks, wherein each network receives as a network input signal, a single one of said narrowband output signals into a detector and integrator network to produce an output command signal only when the voltage across a channel exceeds a predetermined level.