Research in Motion Corporation

P.j. Edmonson Ltd.

Colin K Campbell

Peter J Edmonson

William D Hunt

A system is for encoding information on a passive surface acoustic wave (SAW) device. The system includes a requesting unit configured to wirelessly transmit an impulse signal. The impulse signal is a signal that includes only a single pulse. A SAW device has an interdigital transducer (IDT) configured to physically store coded data. The SAW device is configured to receive the impulse signal. In response to receiving the impulse signal, the SAW device excites the IDT to generate a coded signal that includes the stored coded data and frequency components at a fundamental frequency.

Wireless communication system using surface acoustic wave (SAW) second harmonic techniques

An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, internal dimensions of IDTs are inversely proportional to operating frequency, such that high frequency IDTs present significant manufacturing difficulties. Fabrication of IDTs for high frequency applications is simplified by exploiting a harmonic frequency SAW generated by IDTs. An IDT may therefore be designed according to fundamental frequency internal dimension criteria but can operate at a multiple of the fundamental frequency, thereby providing much higher frequency operation than conventional SAW systems. Operation of a second harmonic SAW system at 2.4 GHz based on a fundamental frequency of 1.2 GHz is contemplated.

A SAW communication device has a main IDT mounted on an SAW substrate to receive an RF signal received by an antenna and convert the RF signal to an acoustic wave which travels along the SAW substrate in opposite directions from the main IDT. At least two secondary IDTs are mounted on the SAW substrate on opposite sides of and spaced from the main IDT to receive and reflect the acoustic wave in a modulated form such that the modulated acoustic wave from one secondary IDT is delayed relatively to the modulated acoustic wave from a secondary IDT on the opposite side of the main IDT to the one secondary IDT. The main IDT is also operable to receive and convert the reflected modulated acoustic waves to a further RF signal with a concatenated waveform corresponding to the two modulated acoustic waves and transmit the further RF signal from the antenna.

Multi-IDT SAW hybrid communication system

A surface acoustic wave sensor or identification device has a piezoelectric material, and an interdigitated transducer (IDT) input/output mounted on the piezoelectric material for receiving a radio frequency (RF) signal and propagating a corresponding surface acoustic wave along a surface of the piezoelectric material. An IDT finger electrode array is mounted on the piezoelectric material and is operable to communicate with the IDT input/output for transmission of a modified RF signal from the device. The IDT finger electrode array has at least one finger electrode segment whose propagating characteristics are controlled to control the nature of the modified RF signal. A biolayer is mounted on the piezoelectric material and is associated with the finger electrode segment, and a fluidic chamber is associated with the biolayer. In use, the fluidic chamber contains fluid which, if a predetermined substance to be sensed or detected is present, operates to modify the biolayer which in turn controls the nature of the modified RF signal.

Surface acoustic wave sensor or identification device with biosensing capability

A SAW RFID tag or sensor has an antenna for receiving and propagating an RF signal, an input/output IDT electrically connected to the antenna, and a dual track reflective IDT having a first track and a second track located adjacent and acoustically coupled to the input/output IDT. An RF signal received from the antenna by the input/output IDT is transformed by the input/output IDT into an acoustic way which is propagated to the dual track IDT. One track of the dual track IDT is in-phase with the phase reference of the input/output IDT and the other track is in quadrature phase with said phase reference. The input/output IDT receives two orthogonal complex modulated acoustic waves reflected from the first and second tracks and transforms them to a modulated orthogonal complex RF signal which is propagated from the antenna.

Dual track surface acoustic wave RFID/sensor

A surface acoustic wave sensor or identification device has a piezoelectric substrate, an interdigitated transducer (IDT) input/output mounted on a substrate for receiving a radio frequency (RF) signal and propagating a corresponding surface acoustic wave along a surface of the substrate. An IDT reflector array is mounted on the substrate and operable to receive a surface acoustic wave and reflect the surface acoustic wave in modified form back to the IDT input/output for transmission of a corresponding modified RF signal from the device. The IDT reflector array has at least one reflector segment whose reflectivity characteristics are controlled to control the nature of the modified RF signal.

Selectable reflector arrays for SAW sensors and identification devices

A group of SAW RFID tags or sensors each has a transducer with interdigitated fingers, a different set of fingers in each tag or sensor being reversed in phase to cause the tag or sensor to provide a unique identifier in a returned impulse response produced by the tag or sensor when interrogated by an interrogation signal.

Encoded SAW RFID tags and sensors for multi-user detection using IDT finger phase modulation

SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, internal dimensions of IDTs are inversely proportional to operating frequency, such that high frequency IDTs present significant manufacturing difficulties. Fabrication of IDTs for high frequency applications is simplified by exploiting a harmonic frequency SAW generated by IDTs. An IDT may therefore be designed according to fundamental frequency internal dimension criteria but can operate at a multiple of the fundamental frequency, thereby providing much higher frequency operation than conventional SAW systems. A communication system based on SAW harmonic techniques would be low-cost, low-power, small and simple alternative to known short range communications schemes, including for example the Bluetooth&trade; solution. Operation of a second harmonic SAW system at 2.4 GHz based on a fundamental frequency of 1.2 GHz is contemplated.

An adaptive tuning method for a wireless communication device determines the impedance of a matching circuit relative to an impedance to be matched and adjusts the impedance of the matching circuit accordingly. A passive surface acoustic wave (SAW) device includes multiple terminated interdigital transducers (IDTs) which generate reflected SAWs when excited by incident SAWs, each reflected SAW having magnitude and phase characteristics dependent upon the particular IDT termination. According to the invention, the IDT terminations include the impedance matching circuit and the impedance to be matched. Input IDTs in the SAW device are excited with electrical signals, which are converted to generate the incident SAWs. The resultant reflected SAWs are converted by output IDTs into output electrical signal signals which can then be analyzed to determine magnitude and phase differences between the output electrical signal signals and generate an impedance matching circuit control signal based thereon.

Adaptive tuning device and method utilizing a surface acoustic wave device for tuning a wireless communication device

SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, conventional SAW expanders and compressors typically have insertion losses greater than 20 dB, which can have a profound effect on an RF link budget in a communication system. Insertion losses are drastically reduced by using a single phase unidirectional transducer (SPUDT-type) instead of a conventional IDT as a SAW expander/compressor. A SPUDT-type reflects SAW components which are lost in conventional IDT designs so that a stronger SAW is directed toward a transmission element. In a receiver, a SPUDT-type directs a stronger SAW toward a compressor IDT. A communication system based on SPUDT-type techniques would be low-cost, low-power, small and simple alternative to known short range communications schemes, including for example the BLUETOOTH&trade; solution. Operation of a SAW system at a frequency of 2.4 GHz is contemplated.

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Ancaster, Canada

Colin K Campbell