Stanley G. Burns

Thin film resonator technology

Advances in wireless systems have placed increased demands on high performance frequency control devices for operation into the microwave range. With spectrum crowding, high bandwidth requirements, miniaturization, and low cost requirements as a background, the thin film resonator technology has evolved into the mainstream of applications. This technology has been under development for over 40 years in one form or another, but it required significant advances in integrated circuit processing to reach microwave frequencies and practical manufacturing for high-volume applications. This paper will survey the development of the thin film resonator technology and describe the core elements that give rise to resonators and filters for todays high performance wireless applications.The thin film resonator technology has been under development for over forty years in one form or another. Although the basic approach is derived from the desire to reach higher frequencies than those readily achieved by thinning bulk crystals, there have always been competing technologies or fundamental material or processing problems that have impeded the development. Finally, a point was reached in the wireless market wherein competing technologies appeared unable to meet the demands of modern wireless applications and thin film approaches began to receive some emphasis. This paper will survey the thin film resonator technology. Every effort will be made to provide an objective analysis of the technology in relation to applications and competing technologies, and point out obstacles and promises, as known, for further technology advancement to high frequencies.

Detection of heart murmurs using wavelet analysis and artificial neural networks.

This paper presents the algorithm and technical aspects of an intelligent diagnostic system for the detection of heart murmurs. The purpose of this research is to address the lack of effectively accurate cardiac auscultation present at the primary care physician office by development of an algorithm capable of operating within the hectic environment of the primary care office. The proposed algorithm consists of three main stages. First; denoising of input data (digital recordings of heart sounds), via Wavelet Packet Analysis. Second; input vector preparation through the use of Principal Component Analysis and block processing. Third; classification of the heart sound using an Artificial Neural Network. Initial testing revealed the intelligent diagnostic system can differentiate between normal healthy heart sounds and abnormal heart sounds (e.g., murmurs), with a specificity of 70.5% and a sensitivity of 64.7%.

Thin Film Resonator Based Low Insertion Loss Filters

Progress on the TFR SCF (stacked crystal filter) configurations is reported including device performance, modeling, design, and materials requirements. Both Si- and GaAs-substrate-based filters are reported with GaAs receiving increased emphasis for microwave integrated circuit applications. The experimental results reported are the result of a number of device feasibility studies done in the course of developing the technology toward its fully integrated form. Filters having insertion losses less than 1.6 dB, with two pole equivalent responses, have been demonstrated at frequencies between 1 and 2 GHz. These filters, using aluminum nitride as the piezoelectric, are approximately 1 mm/sup 2/ in area and designed for a 50- Omega impedance level.<<ETX>>

Detection and Classification of Cardiac Murmurs using Segmentation Techniques and Artificial Neural Networks

In this paper we present the implementation of a diagnostic system based on artificial neural networks (ANN) that can be used in the detection and classification of heart murmurs. Segmentation and alignment algorithms serve as important pre-processing steps before heart sounds are applied to the ANN structure. The system enables users to create a classifier that can be trained to detect virtually any desired target set of heart sounds. The output of the system is the classification of the sound as either normal or a type of heart murmur. The ultimate goal of this research is to implement a heart sounds diagnostic system that can be used to help physicians in the auscultation of patients and to reduce the number of unnecessary echocardiograms - those that are ordered for healthy patients. Testing has been conducted using both simulated and recorded patient heart sounds as input. Three sets of results for the tested system are included herein, corresponding to three different target sets of simulated heart sounds. The system is able to classify with up to 85 plusmn 7.4% accuracy and 95 plusmn 6.8% sensitivity. For each target set, the accuracy rate of the ANN system is compared to the accuracy rate of a group of 2nd year medical students who were asked to classify heart sounds from the same group of heart sounds classified by the ANN system. System test results are also explored using recorded patient heart sounds

Design and Performance of Oscillators Using Semiconductor Delay Lines

Bulk-acoustic-wave piezoelectric thin-film technology has been used to synthesize delay lines at microwave frequencies in semiconductor substrates. These structures use either ZnO or AlN for piezoelectric transduction, suitably positioned electrodes for applying an ac signal, and reflecting surfaces for guiding the acoustic energy. the top-side of the semiconductor wafer. We can incorporate these delay structures as the feedback element in an oscillator and exploit the 2n periodicity in these structures to obtain a comb generator output. delay-line oscillators operating near 1 GHz and 3 MHz spectral line spacing. exceeds -90 dBc/Hz at 1 kHz. Design and analysis is based upon the use of SPICE 2G linear circuit models. Because the transducer fabrication process uses semiconductor processing technology as its basis, the synthesis of these oscillators is being studied as an integrable alternative to other technologies. The delay lines are accessed entirely

A micromachined sensor array using thin film resonators

This paper describes the design, modeling and implementation of a microsensor array using aluminum nitride thin film resonators. A finite element method, formulated to accommodate the anisotropic and piezoelectric properties of aluminum nitride, is used to model acoustic wave coupling between resonators and to define the mask design. Two arrays on the same aluminum nitride membrane were fabricated using standard semiconductor processing. The measurements were in agreement with the modeling. A multilayer Mason model was applied to investigate the mass loading and viscoelastic effects via hydrogen absorption on the PdNi coated TFR. The preliminary H/sub 2/ sensitivity tests on a TFR hydrogen sensor are also presented.

Design and performance of voltage-controlled oscillators using TFR stacked-crystal filters

Two applications of thin-film resonator (TFR) technology are presented. These designs are: a 1-GHz voltage-controlled oscillator (VCO) with a 0.5% tuning range, and a frequency-agile 1-GHz oscillator which provides discrete frequency shifts of 4 MHz. The basic TFR frequency-control structure is a stacked-crystal filter (SCF) synthesized using multiple layers of AlN for piezoelectric transduction sandwiched between Al electrodes. Filters can be synthesized with single-mode bandpass or multiple (over-moded) bandpass characteristics. Typical performance for a single-mode double-stacked filter, when used in a 1-GHz VCO, provides an insertion loss as low as 1.5 dB, a linear phase extending over a 20-MHz passband, and an open-loop Q=80. The VCO was designed using a large-signal perturbational S-parameter technique.<<ETX>>

Fundamental-Mode Pierce Oscillators Utilizing Bulk-Acoustic-Wave Resonators in the 250 - 300 MHz Range

Fundamental-mode Pierce Oscillators in the 250-300 MHz range have been realized utilizing a unique form of a bulk-acoustic-wave (BAW) resonator. Phase noise of -100 dbc/Hz (1 KHz offset) and output power levels of +6 dbm have been demonstrated. A linear-model design was used. The circuit topology and resonator fabrication technique show great promise for creation of monolithic circuits in the 200 MHz to 2 GHz range.

A state-variable approach to symbolic circuit simulation in the time domain

Presents a hierarchical method for performing symbolic simulation in the time domain using a state-variable approach. The authors illustrate the development of the symbolic state-variable matrices for the subcircuits of a partitioned network, and the methodology for the hierarchical analysis. The resultant state equations are combined to produce the compact state-variable equations for the entire system. This hierarchical method exhibits a large reduction in the number of operations and in the size of the characteristic matrices needed to characterize the state variable equations for the network. This enables the application of the method to large-scale networks. The method accommodates a model for ideal operational amplifiers.<<ETX>>

High frequency oscillators using cointegrated BAW thin-film piezoelectrics with microwave BJTs

The authors report on the design of UHF and L-band oscillators using of sputter-deposited, thin-film, aluminum nitride resonators cointegrated with microwave f/sub T/=2.5 GHz bipolar junction transistors (BJTs). This technology uses reactive ion etching (RIE) trench-isolated 2.5-GHz BJTs cointegrated with high-Q AlN resonators synthesized with an anisotropic etch along the