Abstract: A communications apparatus and method use tapped delay lines as multiplexers and demultiplexers. In one embodiment, a receiver (100) uses a tapped delay line (110) as a demultiplexer to acquire a burst communication at very high data rates in the range of 2.5 to 80 Gbps with low preamble overhead. A sliding window correlator (114) continually samples the delay line (110) to determine when a PN encoded word is contained therein. The transmission frequency is pre-acquired before any data is present through the use of a ring oscillator frequency calibration loop (130) that is imbedded within the tapped delay line (110).

Abstract: A reflective grating (18) having spaced grid lines (36) patterned on a piezoelectric substrate (12) for controlling the magnitude and phase of surface acoustic waves (28) in a reflective filter (10) or resonator. The magnitude and phase of the surface acoustic wave (28) are controlled by a sampling period (34) of the reflective grating (18) and the density and sequence of distributed acoustic reflective dots (42). The reflective dots (42) are randomly distributed within gaps (40) between adjacent grid lines (36) or on top of the grid lines (36) of the reflective grating (18). The pattern of the reflective dots distributed within the gaps (40) or on the grid lines (36) is determined by the dot density, where the dot density varies from a lowest density of 0 to a maximum density of 1.

Abstract: A dual track SAW reflector filter (150) including a first track (152) and a second track (154). The first track and the second track (152, 154) include an input transducer (156, 164), an output transducer (158, 166), first reflectors (160, 168) and second reflectors (162, 170). The reflectivity function of the first reflectors (160, 168) and the second reflectors (162, 170) are equal in magnitude and opposite in phase. The input transducers (156, 164) have the same polarity and the output transducers (158, 166) have opposite polarities. Surface acoustic waves produced by the input transducers (156, 164) and received directly by the output transducers (158, 166) are in phase and cancel at the output transducers (158, 166). Surface acoustic waves reflected by the reflectors (160, 162, 168 and 170) are in phase and add at the output transducers (158, 166).

Abstract: A reflective grating (18) having spaced grid lines (36) patterned on a piezoelectric substrate (12) for controlling the magnitude and phase of surface acoustic waves (28) in a reflective filter (10) or resonator. The magnitude and phase of the surface acoustic wave (28) are controlled by a sampling period (34) of the reflective grating (18) and the density and sequence of distributed acoustic reflective dots (42). The reflective dots (42) are randomly distributed within gaps (40) between adjacent grid lines (36) or on top of the grid lines (36) of the reflective grating (18). The pattern of the reflective dots distributed within the gaps (40) or on the grid lines (36) is determined by the dot density, where the dot density varies from a lowest density of 0 to a maximum density of 1.

Abstract: A dual track SAW reflector filter (150) including a first track (152) and a second track (154). The first track and the second track (152, 154) include an input transducer (156, 164), an output transducer (158, 166), first reflectors (160, 168) and second reflectors (162, 170). The reflectivity function of the first reflectors (160, 168) and the second reflectors (162, 170) are equal in magnitude and opposite in phase. The input transducers (156,164) have the same polarity and the output transducers (158, 166) have opposite polarities. Surface acoustic waves produced by the input transducers (156, 164) and received directly by the output transducers (158, 166) are in phase and cancel at the output transducers (158, 166). Surface acoustic waves reflected by the reflectors (160, 162, 168 and 170) are in phase and add at the output transducers (158, 166).

Abstract: An acoustic charge transport device is formed by a process which introduces a process dependent variation in charge carrier density within the device. The acoustic charge transport device includes a transport channel operable to carry charge carriers in response to a surface acoustic wave. In addition, the acoustic charge transport device further includes a backgate for controlling the charge carrier density within the transport channel.

Abstract: A relatively narrow fractional bandwidth saw filter formed on a standard ST cut of quartz. The electrode pattern is modified in order to eliminate distortion. In particular, the overlap pattern is formed with one or less active overlaps per wavelength in those regions of the SAW filter where the weighing function is maximum. A plurality of six finger/.lambda. electrode patterns with two active overlaps per wavelength is also provided.

Abstract: A relatively narrow fractional bandwidth saw filter formed on a standard ST cut of quartz. The electrode pattern is modified in order to eliminate distortion. In particular, the overlap pattern is formed with one or less active overlaps per wavelength in those regions of the SAW filter where the weighing function is maximum. A plurality of six finger/.lambda. electrode patterns with two active overlaps per wavelength is also provided.

Abstract: This invention discloses a monolithic multipole stacked crystal filter comprised of a series of cascaded 2-port semiconductor bulk acoustic resonator stacked crystal filters electrically cascaded and a shunt inductor connected between each of the 2-port filters. Each of the 2-port filters including a first and second piezoelectric layer, typically aluminum nitride. A first input electrode is positioned on a top surface of one of the piezoelectric layers and a second output electrode is positioned on a bottom surface of the other of the piezoelectric layers. A ground electrode is positioned between the piezoelectric layers. In this regard, the piezoelectric layers will resonate at a resonant frequency and provide bandpass filter characteristics. The complete monolithic multipole filter provides control of the passband shape which yields highly desirable filter characteristics.

Abstract: A surface acoustic wave (SAW) filter consists of two acoustically coupled transducers built on the same piezoelectric film or substrate. The transducers are constructed by depositing a conducting comb structure having interdigitated fingers on the substrate. Spacer elements are placed between gaps of the same polarity within the comb structure. The addition of the spacer elements permit non-zero gap weights of the same sign to follow one another, in contrast to the standard structure which forces these sources to alternate in sign. This added flexibility results in new withdrawal weighted structures that significantly increase the bandwidth over which the rejection band performance is good and also reduces passband ripple. The increase in the accuracy of the withdrawal weighting permissible with these new structures improves filter performance.