Microwave filters possessing various forms are essential components in radar, satellite, and mobile communication systems. Increased demands for low-loss, miniature filters that can be mass produced at low cost have provided a significant challenge reinforcing the need for improving or even replacing the conventional microwave filters. In recent years, the concept of Photonic/Electromagnetic Bandgap (PBG/EBG) structures has attracted the attention of the microwave engineering community. The main feature of PBG/EBG structures is the existence of a bandgap in the frequency spectrum of a propagating photonic/electromagnetic wave. The motivation for adopting EBG structures stems from their capability to eliminate unwanted wave propagations in various microwave devices. This thesis investigates and proposes novel planar microstrip filters employing EBG structures in the form of slots etched on the ground plane. Such filters are not only compact, but also can improve the RF performance in both the passband and the stopband. This proposed concept is further extended to implement low-loss tunable lowpass filters, both digital and analogue, by integrating tuning elements directly into the slots. Transmission line circuit models are developed to design the proposed microstrip filters and tunable lowpass filters. To verify the concept and the validity of the developed circuit models, theoretical and experimental results are presented and carefully compared. Currently, dielectric resonator (DR) filters have been widely employed in wireless and satellite communication systems. Over the past two decades, tremendous progress has been made to reduce the size, and enhance the in-band and out-of-band performance of DR filters. However, the current approaches for implementing DR filters are relatively expensive and hardly amenable to mass production. Cost reduction remains a key limiting factor that needs to be addressed now. A new configuration of DR filters is presented in this thesis. The novel concept simplifies the assembly, integration, and alignment of DR filters, significantly reducing production time and costs. Not only is the design of the proposed multi-pole DR filters and diplexers examined, but also the fabrication technique. The experimental measurement results confirm the validity of the theoretical designs of the new filters, which makes this concept very attractive for further applications in both wireless and satellite communication.

This thesis is concerned with the study and design of three integrated filters for biomedical applications. The following designs are considered: A 2nd-order high-pass filter with low cut-off frequency (Design 1), a 2nd-order low-pass filter with high cut-off frequency (Design 2), and a 1st-order high-pass filter with low cut-off frequency (Design 3). Design 1 and 2 are intended for separating the physiological signal and a high-frequency test signal in the application of a chip safety monitoring system. Design 3 finds its application in a system for adaptive sampling of the electrocardiogram. The details of the applications are not part of this thesis. Design 1 is composed of operational transconductance amplifier (OTA) and capacitances. The thesis adopts an 2nd-order fully-differential HP filter and uses conventional folded-cascode OTAs to realize the fully-differential HP filter. By proper designing the transistor sizes of the OTA, the HP filter can achieve specific specification in our biomedical system. Its post-layout simulated cut-off frequency is 316 kHz and the total harmonic distortion is -40.14dB with a 1MHz 2 Vp-p input signal. Design 2 is also composed of OTA and capacitances. To overcome the linearity problem of OTA, so-called symmetrical and asymmetrical differential pairs are utilized to design a more linear transconductor. Moreover, a conventional gate voltage-controlled negative resistor circuit with CMFB circuit is used to create the required high output impedance of the OTA. The CMFB circuits are used to stabilize the output dc level in the OTA. The OTA is used to realize a fully-differential 2nd-order LP filter. By proper designing the transistor sizes of the OTA, the filter can achieve specific specification in our biomedical system. The filter¡¦s post-layout simulated cut-off frequency is 12.93 MHz and the total harmonic distortion is -47.14 dB with a 10 MHz 1 Vp-p input signal. Design 3 uses an RC filter design with bulk-drain connected MOS transistors biased as an active high-value resistor. A cut-off frequency of 647 Hz is thus achieved on an active area of 0.012 mm2. Test chips were fabricated in TSMC 0.35 £gm CMOS technology for Designs 1 and 3 and the measured results are reported, confirming the operation of the filters.

An on-chip automatic tuning circuit is proposed. The circuit is applied to a 3.3V 1.1MHz butterworth low-pass Gm-C filter for ADSL (Asymmetric Digital Subscriber Loops). A new frequency tuning method is used to adjust the cut-off frequency of the filter. The frequency tuning circuit can reduce the tolerance due to process variations and without a large off-chip capacitor. HSPICE simulations and experimental results verify the proposed circuits. All the circuits are designed based on the TSMC 0.35um 2p4m CMOS process technology.

Berlin, Techn. Univ., Diss., 2002. / Computerdatei im Fernzugriff.

Berlin, Techn. Univ., Diss., 2002. / Computerdatei im Fernzugriff.

<p>How to create a more effective filter for the dishwashers of tomorrow.</p>

How to create a more effective filter for the dishwashers of tomorrow.

Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 7 uppsatser.

Diss. Nr. 7284 techn. Wiss. ETH Zürich.

Neubiberg, Univ. der Bundeswehr München, Diss., 2008