Waguih S. Ishak

Magnetostatic surface wave straight-edge resonators

The performance of the magnetostatic surface wave straight-edge resonator (MSSW-SER) is presented. The resonator uses a rectangular YIG film to propagate MSSWs where the straight edge serves as a reflector. Problems arising from coupling to width mode resonances and their effect on the main resonance are investigated. Through a careful choice of YIG and transducer parameters, the interference effects of the width mode resonances with the main resonance are minimized. As a result, highQ tunable microwave resonators with a tuning range from 2–20 GHz, insertion loss less than 10 dB, and spurious rejection better than 10 dB could be designed and fabricated. This MSSW resonator could be used to construct a tunable low-phase-noise feedback oscillator. However, the tuning range of this MSW feedback oscillator is limited by the phase change of the external amplifier circuit.

Optical interconnects: the Parallel Optical Link Organization (POLO) approach

The Parallel Optical Link Organization (POLO) is an industry consortium of Hewlett-Packard, Du Pont, AMP, University of Southern California, and SDL, supported by ARPA and will operate between August 1994 and August 1997. The POLO Consortium was formed to leverage the individual strengths of its members to develop low-cost, high-performance optical interconnect modules for applications in workstation clusters, high-speed switching systems, and multimedia. The goal of the program is to demonstrate the manufacturability of affordable optoelectronic transceiver modules and to provide application platforms that show a clear advantage over copper-wire interconnections. The technical objective of the program is to provide a 10 - 20 Gb/s parallel channel optical interconnect module with a projected manufacturing cost of about

Tunable microwave resonators and oscillators using magnetostatic waves

10 per channel. In addition, the POLO Consortium provides a complete solution to the end user, including a programmable host interface module and software interface. The POLO Consortium has formed a User Group consisting of seven world-leading computer, telecommunication, and optoelectronic subsystem manufacturers. Regular meetings with the User Group are planned and at the first meeting, a full set of POLO Module specifications have been discussed and generated. The POLO Consortium will provide the User Group members with hardware for evaluation and feedback.

Magnetostatic Forward Volume Wave Straight Edge Resonators

The status of magnetostatic wave (MSW) straight-edge resonators (SERs) and their applications in tunable oscillator circuits are reviewed. The resonators are based on magnetostatic waves propagating in high-Q cavities fabricated in thin ferrimagnetic yttrium iron garnet (YIG) films. The resonance frequency of these resonators can be tuned using a bias magnetic field. The theory of operation and design criteria for the straight-edge resonators are described with emphasis on the effect of the resonator parameters on the tuning range, power handling, and phase noise performance. The use of the SER as the frequency-selective element in oscillator circuits is reported. Examples of tunable oscillators are included.<<ETX>>

MSW-SER Based Tunable Oscillators

The preformance of Magnetostatic Forward Volume Wave Straight Edge Resonators (MSFVW-SER) is presented. The resonator uses a rectangular YIG film to propagate Magnetostatic forward volume waves where the straight edges serve as reflectors. The interference of width mode resonances with the main resonance reported in the MSSW-SER is not observed in the MSFVW-SER. As a result, high-Q tunable microwave resonators with a tuning range from 1-20 GHz, insertion loss less than 8 dB and spurious rejection better than 10 dB have been designed and fabricated.

Phase Noise Characteristics of MSW Devices

Tunable Magnetostatic Wave Straight Edge Resonators (MSW-SERs) offer an alternative to YIG spheres and varactor diodes in microwave oscillators. Work on MSW-SERs is extended to coupling with active devices. Interactions increase insight into resonator characteristics. A brief review of resonator-based microwave oscillator topologies precedes a survey of available YIG/GGG materials and coupling structures. Circuit related properties of the MSW-SER are presented as a basis for design. Circuit topologies are compared and the negative resistance topology is selected. Several examples of tunable oscillators in the L, S, and K microwave frequency bands will be given with emphasis placed on tuning bandwidth, power handling, harmonic distortion and phase noise characteristics.

Tunable magnetostatic wave oscillators using pure and doped YIG films

The phase noise characteristics of Magnetostatic Wave (MSW) delay lines, resonators and oscillators were investigated using doped and pure YIG films. Both l/f and white noise spectral densities were observed in passive MSW devices. It was also noticed that the white noise spectral density was a function of the incident power to the device and YIG linewidth; decreasing for lower incident power and higher linewidth YIG films. The phase noise measurement configurations will be discussed in detail, together with the results obtained. A simple explanation of the power and linewidth dependence of the white noise floor will be given.

The Effect of Width Modes on the Performance of MSSW Resonators

The performance of magnetostatic surface wave delay line oscillators (MSWDLO) is presented. The oscillator consisted of a narrow band MSSW delay line in a feedback loop around a solid state amplifier. Power is coupled out by a directional coupler. A frequency range of 0.5-24 GHz was covered using highly doped, lightly doped and pure YIG films epitaxially grown on GGG substrates. The MSWDLO exhibited essentially linear tuning characteristics with output power greater than +5 dBm. Temperature cycling tests showed about 3 MHz/ °C variation in oscilation frequency over the 25-105 °C range. Phase noise measurements at different frequencies showed the single side band phase noise was typically less than -100 dBc at 10 kHz offset.

Magnetostatic wave devices for UHF band applications

Theoretical and experimental investigations were performed to study width mode resonances (WMR) observed in magnetostatic surface wave straight edge resonators (MSSW-SER). It was found that for each principal resonance (n=1,2,3, m=l) of the MSSW-SER, different width mode resonances (m=2,3 ,... ) can be excited. Even and odd width modes can be excited depending on the RF current distribution in the microstrip transducers. Furthermore, all high order width mode resonances (m=2,3,4 ... ) occur at the low frequency side of the principal resonances (n=1,2,3, m=l). At high operating frequencies (e.g. above 4 CHz for pure YIC devices) the frequency separation between the principal resonances decreases and as a result, the width modes corresponding to high order principal modes will interfere with the low order principal modes. Through a careful choice of YIG and transducer parameters, the interference effects of width modes were minimized. Tunable high Q MSSW resonators with low insertion loss ( lOdB) have been designed and fabricated.

Multi gigabit per second optical interconnects technology for computer and communication applications

Magnetostatic surface wave (MSSW) devices made with pure and gallium-substituted yttrium-iron garnet (Ga:La-YIG) films are described. These devices include nondispersive and dispersive delay lines, band-pass filters, oscillators, and resonators. By controlling the magnitude of the bias magnetic field and the temperature of operation, it is possible to tune these devices over a wide frequency range extending from 0.3 to 4 GHz and from 3 to 18 GHz using Ga:La-YIG and pure YIG films, respectively.These devices could be used in pulse compression radar, microscan receivers, complicated Fourier transform processors, and fundamental oscillator circuits. In this paper, we briefly show results for pure YIG devices tunable in C and X bands and discuss, in detail, the performance of the Ga:La-YIG devices for UHF applications.