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High-speed switched-capacitor filters based on unity-gain buffersBruneau, David 22 April 2002 (has links)
In this work a new voltage buffer, the drain-follower, achieves 300MHz band-width
with 2pF load, a dc gain of 0.993V/V, 1mV offset voltage, -60 dB total harmonic
distortion at 1.4Vpp output voltage and 6.5mW power dissipation from 5V
supply. A unity-gain buffer switched-capacitor biquad filter has been implemented
in 0.5��m CMOS technology. The circuit has been sent for fabrication. Simulation
results of the biquad filter indicate operation at 100MHz with 20mW power
consumption from a 5V supply can be achieved. / Graduation date: 2002
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Inorganic mesoporous membrane for water purification applications synthesis, testing and modeling /Yu, Di. January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request
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Superconducting Microwave FiltersSetoodeh, Sormeh 24 January 2011 (has links)
Superconducting microelectronics (SME) technology has the potential of realizing very high speed digital receivers capable of performing direct digitization of radio frequency signals with very low power consumption. The SME receiver is implemented on a single chip using Niobium based low temperature superconductive (LTS) Josephson Junction (JJ) technology by HYPRES. Analogue RF filters are still required at the receiver front end and are key components of the overall superconductor digital receiver. SME receivers usually require two types of RF filters; a wideband bandpass filter and a bandstop filter (a notch filter). The notch filter is required to eliminate interference and unwanted signals in the passband. In this thesis, design of highly miniaturized lumped element wideband and bandstop filters is investigated and some challenges are addressed. The filters are fabricated by the HYPRES process and therefore can be integrated with the SME receiver on the same chip.
In a wideband filter, the coupling between the adjacent resonators is high. Achieving such a strong coupling is one of the challenges of designing wideband filters. The wideband filters realized with distributed elements usually suffer from very low spurious frequency. As the bandwidth of the filter becomes wider, the spurious peak of the second harmonic gets closer to the passband of the filter. In the first part of this work, the possibility of realizing lumped element superconducting bandpass filters (BPF) with a relative bandwidth of 80% is investigated.
In the second part of the thesis, design and realization of lumped element superconducting bandstop filters (BSF) is discussed. The challenge for designing a bandstop filter is providing a good match over a wide frequency range. So narrowband inverters cannot be used. Instead, usually λ/4 matched transmission lines provide 90° phase shift between the resonators of a notch filter. The possibility of replacing the long transmission line with other means or eliminating the inverters and using both shunt and series resonators are investigated. Having both series and shunt resonators introduces some new challenges that are addressed in the thesis and discussed thoroughly.
A tunable notch resonator is presented. The tunability is provided by a superconducting MEMS varactor that is realized in our group by doing some post processing on the device fabricated by HYPRES. The tunability range of the device at cryogenic temperatures is investigated. A 3-pole tunable BSF is also designed that uses the same tunable resonators. The tunability of the filter is investigated through simulation.
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Fabrication and Characterization of Tunable Thin-film FiltersLee, Mao-Sian 23 June 2006 (has links)
The subject of this dissertation is to fabricate a tunable filter for WDM applications using thin film filters (TFFs). The center-wavelength shift of the TFF was obtained by heating up the TFFs.
To enhance the thermal effect on the wavelength shift of the filters, the thickness of the TFFs were reduced from 1 mm to a minims thickness of 150£gm. Si benches with etched V-grooves were fabricated for precision positioning of the TFFs after thinning. For a 200 £gm ¡Ñ 200 £gm devices, maximum wavelength shift of 1.248nm was obtained by heating up the filter to 250¢XC.
In addition, the wavelength shift due to thinning the substrate of the filters is also discussed.
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Analysis, modeling and simulation of ring resonators and their applications to filters and oscillatorsHsieh, Lung-Hwa 30 September 2004 (has links)
Microstrip ring circuits have been extensively studied in the past three decades. A magnetic-wall model has been commonly used to analyze these circuits. Unlike the conventional magnetic-wall model, a simple transmission-line model, unaffected by boundary conditions, is developed to calculate the frequency modes of ring resonators of any general shape such as annular, square, or meander ring resonators. The new model can be used to extract equivalent lumped element circuits and unloaded Qs for both closed- and open-loop ring resonators. Several new bandpass filter structures, such as enhanced coupling, slow-wave, asymmetric-fed with two transmission zeros, and orthogonal direct-fed, have been proposed. These new proposed filters provide advantages of compact size, low insertion
loss, and high selectivity. Also, an analytical technique is used to analyze the
performance of the filters. The measured results show good agreement with the
simulated results.
A compact elliptic-function lowpass filter using microstrip stepped impedance hairpin resonators has been developed. The prototype filters are synthesized from the equivalent circuit model using available element-value tables. The filters are evaluated by experiment and simulation with good agreement. This simple equivalent circuit model provides a useful method to design and understand this type of filters and other relative circuits.Finally, a tunable feedback ring resonator oscillator using a voltage controlled piezoelectric transducer is introduced. The new oscillator is constructed by a ring resonator using a pair of orthogonal feed lines as a feedback structure. The ring resonator with two orthogonal feed lines can suppress odd modes and operate at even modes. A voltage controlled piezoelectric transducer is used to vary the resonant frequency of the ring resonator. This tuned oscillator operating at high oscillation frequency can be used in many wireless and sensor systems.
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Nonlinearity and noise modeling of operational transconductance amplifiers for continuous time analog filtersRamachandran, Arun 16 August 2006 (has links)
A general framework for performance optimization of continuous-time OTA-C
(Operational Transconductance Amplifier-Capacitor) filters is proposed. Efficient
procedures for evaluating nonlinear distortion and noise valid for any filter of arbitrary
order are developed based on the matrix description of a general OTA-C filter model .
Since these procedures use OTA macromodels, they can be used to obtain the results
significantly faster than transistor-level simulation. In the case of transient analysis, the
speed-up may be as much as three orders of magnitude without almost no loss of
accuracy. This makes it possible to carry out direct numerical optimization of OTA-C
filters with respect to important characteristics such as noise performance, THD, IM3,
DR or SNR. On the other hand, the general OTA-C filter model allows us to apply
matrix transforms that manipulate (rescale) filter element values and/or change topology
without changing its transfer function. The above features are a basis to build automated
optimization procedures for OTA-C filters. In particular, a systematic optimization
procedure using equivalence transformations is proposed. The research also proposes
suitable software implementations of the optimization process. The first part of the
research proposes a general performance optimization procedure and to verify the
process two application type examples are mentioned. An application example of the
proposed approach to optimal block sequencing and gain distribution of 8th order
cascade Butterworth filter (for two variants of OTA topologies) is given. Secondly the
modeling tool is used to select the best suitable topology for a 5th order Bessel Low Pass
Filter. Theoretical results are verified by comparing to transistor-level simulation withCADENCE. For the purpose of verification, the filters have also been fabricated in
standard 0.5mm CMOS process.
The second part of the research proposes a new linearization technique to
improve the linearity of an OTA using an Active Error Feedforward technique. Most
present day applications require very high linear circuits combined with low noise and
low power consumption. An OTA based biquad filter has also been fabricated in 0.35mm
CMOS process. The measurement results for the filter and the stand alone OTA have
been discussed. The research focuses on these issues.
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High frequency and high dynamic range continuous time filtersLewinski Komincz, Artur Juliusz 17 September 2007 (has links)
Many modern communication systems use orthogonal frequency division
multiplexing (OFDM) and discrete multi-tone (DMT) as modulation schemes where
high data rates are transmitted over a wide frequency band in multiple orthogonal subcarriers.
Due to the many advantages, such as flexibility, good noise immunity and the
ability to be optimized for medium conditions, the use of DMT and OFDM can be found
in digital video broadcasting, local area wireless network (IEEE 802.11a), asymmetric
digital subscriber line (ADSL), very high bit rate DSL (VDSL) and power line
communications (PLC). However, a major challenge is the design of the analog frontend;
for these systems a large dynamic range is required due to the significant peak to
average ratio of the resulting signals. In receivers, very demanding high-performance
analog filters are typically used to block interferers and provide anti-aliasing before the
subsequent analog to digital conversion stage. For frequencies higher than 10MHz, Gm-C filter implementations are generally
preferred due to the more efficient operation of wide-band operational transconductance
amplifiers (OTA). Nevertheless, the inherent low-linearity of open-loop operated OTA
limits the dynamic range. In this dissertation, three different proposed OTA linearity
enhancement techniques for the design of high frequency and high dynamic range are
presented. The techniques are applied to two filter implementations: a 20MHz second
order tunable filter and a 30MHz fifth order elliptical low-pass filter. Simulation and
experimental results show a spurious free dynamic range (SFDR) of 65dB with a power
consumption of 85mW. In a figure of merit where SFDR is normalized to the power
consumption, this filter is 6dB above the trend-line of recently reported continuous time
filters.
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On the design of multiplier-less perfect reconstruction filter banks using genetic algorithm and sum-of-powers-of-two representation /Liu, Wei, January 2000 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references.
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Study of surface regeneration characteristics of a candle filter at high temperatureViswanathan, Balakrishnan, January 2004 (has links)
Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 96-98).
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Synthesis of RC active filter.Cheung, Lap-kit. January 1970 (has links)
Thesis--M. Sc., University of Hong Kong. / Mimeographed.
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