Finite Transmission Zeros Research Articles

Realization of Four Transmission Zeros in a Four-Pole Superconducting Microstrip Filter Using Cross-Shaped Spiral Resonators

The realization of four finite transmission zeros with high-temperature superconducting microstrip narrow-band bandpass filter using four cross-shaped spiral resonators is described for the fully canonical case. The approach is based on the N+2 transversal coupling matrix, which is composed of main direct coupling as well as source/load coupling. The filter, with 0.75% bandwidth, 3.25 MHz, at 408-MHz band, is to be used for a radio astronomy application at Jodrell Bank Observatory, U.K. The measured results match well with both theoretical results and simulated results, except for a small center frequency offset.

Bandpass filter of serial configuration with two finite transmission zeros using LTCC technology

This study proposes a second-order bandpass filter of serial configuration. The filter schema incorporates a grounding capacitor, connecting the two conventional parallel LC resonators with the ground, to provide two finite transmission zeros. The impedance matrix and graphical solutions describe proposed filter's operation principle. To demonstrate the proposed filter schema, two bandpass filters, with center frequencies of 2.44 and 4.8 GHz, were designed and implemented using low-temperature co-fired ceramic multilayer technology. The measured results were found to agree well with the simulation results. The 2.44-GHz fabricated bandpass filter was found to possess low in-band insertion loss and high out-band suppression, making it suitable in wireless local area networks, Bluetooth, and RF home links.

Synthesis and design of in-line N-order filters with N real transmission zeros by means of extracted poles implemented in low-cost rectangular H-plane waveguide

In this paper, an extension to the extracted pole technique for synthesizing N-order filters with N-transmission zeros at real frequencies is presented. In addition, a new bandpass rectangular waveguide H-plane low-cost configuration filter for high-power low-loss application (patent pending) that implements a filtering function with finite real frequency transmission zeros is proposed. This structure operates as a resonant cavity in transmission at central frequency of the bandpass and simultaneously introduces a controlled transmission zero out of the bandpass. Since every double-controlled electrical behavior cavity introduces a transmission zero, it is possible to introduce as many transmission zeros as the order of the filtering function. In order to validate the synthesis procedure and the new structure, different filters have been designed: a second-order filter with two transmission zeros, a third-order filter with one transmission zero, a fourth-order filter with two transmission zeros, and finally, an eighth-order filter with two transmission zeros. The last two have been manufactured, showing an excellent agreement between the measurement and theoretical simulation.

A universal building block for advanced modular design of microwave filters

A universal building block for modular design of microwave filters is introduced. The second order block contains two resonators which are not coupled to each other. By adjusting the strengths and signs of its coupling coefficients, the block can be used to design bandpass, bandstop and linear-phase filters. For bandpass filters, Chebychev as well as symmetric and asymmetric pseudo-elliptic responses with one or two finite transmission zeros can be designed. For linear-phase filters, two finite transmission zeros can placed practically anywhere in the complex plane as long as the realizability condition is met. Bandstop filters with no finite reflection zeros as well as symmetric and asymmetric pseudo-elliptic responses with one or two finite reflection zeros can be achieved by the same building block. The block is so flexible it can even generate bandstop responses with complex finite reflection zeros for group delay control. Higher order filters are designed modularly by cascading the appropriate number of building blocks. Coupling matrices of a number of cases are presented to demonstrate the flexibility and the universality of the building block.

At least N+1 finite transmission zeros using frequency-variant negative source-load coupling

A second-order cross-coupled combline filter which has three finite transmission zeros is presented. The problem of the frequency-invariant coupling in a real circuit is introduced. To make extra transmission zeros, a top metalized dielectric block is used.

A compact second-order LTCC bandpass filter with two finite transmission zeros

A novel implementation and associated design formula for a compact low-temperature cofired ceramics (LTCC) lumped-element second-order bandpass filter are proposed in this paper. The filter schematic that provides two finite transmission zeros is well known. It is shown in the paper that the filter schematic is built on a pair of conventional inductive coupled resonator tanks with a feedback capacitor between input and output. While revealing its working mechanism both graphically and mathematically, a simple design procedure for such a compact filter is also given. The proposed filter has been implemented in a six-layer ceramic substrate using LTCC technology, showing promising application potentials in miniaturized mobile terminals and Bluetooth RF front-ends. The measured results agree very well with the full-wave electromagnetic designed responses.

Design Methods for Micro-Electro-Mechanical Bandpass Filters with Transmission Zeros

A design method for high-order electro-mechanical filters allowing the synthesis of architectures of electro-mechanical filters from equivalent electrical prototypes is presented. Conditions for existence of the equivalent mechanical system for a given electrical network are derived. This method is applied to the problem of the design of band-pass electro-mechanical filters with transmission zeros in the stopband. Electro-statical coupling of micro-mechanical resonators that avoids the use of a mechanical coupling spring is introduced. The application to the simulation and design of a bandpass filter with finite transmission zeros implemented in a thick-layer epi-poly silicon micro-machining technology is shown.

Synthesis and design of N‐order filters with N‐transmission zeros by means of source–load direct coupling

AbstractAn extension is made to the synthesis of microwave filters with cross couplings between nonadjacent cavities to the case where there is a direct coupling between the input and output ports, i.e., the source and the load of the device. This coupling extends to N‐order filters the possibility to accomplish responses with N finite transmission zeros. In addition, symmetric and asymmetric rejection slopes out of band and equalized group delay can be obtained simultaneously. Several examples of filter synthesis are presented to validate the proposed synthesis procedure. Finally, to show the applicability of the load–source direct coupling, a second‐order Ku‐band filter with two transmission zeros has been designed using three physical structures: two different rectangular waveguide E‐plane configurations and one H‐plane. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 248–252, 2001.

Two-port equivalences for bandpass filters

This brief describes a set of equivalences to be used to implement one or two finite transmission zeros in a bandpass [inductance-capacitance (LC) or microwave] filter in the form of three or four grounded resonators with multiple coupling branches. A generalization of the Norton (impedance) transformation is also described for circuits that contain multiple coupling branches.

HTS AMPS-A and AMPS-B filters for cellular receive base stations

The multiple, interleaved pass band nature of the AMPS cellular system provides an excellent opportunity for high performance HTS filter technology for base station reverse link applications. The 25 MHz spectrum is divided into 4 unequal bands, 2 each for the A and B operators. For AMPS-A, the two band pass filters are connected in parallel, while for AMPS-B a band pass filter is cascaded with a band reject filter. All band pass filters have finite transmission zeros and the band reject filter is designed to have an equal ripple stop band. The design and performance of high selectivity filters for this application is described.

On the maximum number of finite transmission zeros of coupled resonator filters with a given topology

This letter presents a rigorous proof of the maximum number of finite transmission zeros which can be achieved by a network of coupled resonators with a fixed topology matrix. Once the topology matrix is fixed, the number of finite transmission zeros cannot exceed this number regardless of the choice of the frequency-independent coupling coefficients M/sub ij/.

On the Elimination of Reactive Element Loops and the Useof Special Approximations in the Design of OTA-C Filters

Loops of reactive elements in passive filters cause a series of problems in OTA-C simulations of these structures. These loops can be eliminated in a systematic way by the procedures described in the paper. The use of special approximations in the design of the passive prototype filters allows the elimination of multiple loops of reactive elements that appear in usual LC ladder filters with finite transmission zeros. This leads to more efficient active simulations, where problems with floating capacitors, DC or high-frequency instability, or limited operating frequency are avoided.

Table-based log-domain linear transformation filter

A design table for realising log-domain linear transformation filters is presented. Based on this design table, doubly terminated LC ladder filters with or without finite transmission zeros can be efficiently synthesised. Moreover, two design procedures are also given. A canonical log-domain elliptic ladder filter can be realised using one of these procedures. Simulation results are given to verify the theoretical analysis.

A family of modular fully differential witched capacitor filters for simulating ladder filters

AbstractThe switched capacitor filters proposed in this paper are based on the simulation of LC ladder filters through the state variable equations. They include all‐pole and finite transmission zero, lowpass filters, bandpass and highpass filters. the introduced family of filters has a fully differential structure; consequently it has the advantages of improved power supply and common mode rejection ratios and extended dynamic range. Since the proposed family of filters simulates LC ladder filters, it inherits their low passband sensitivities. One of the main advantages of this family of filters is that it has a modular structure composed of key and auxiliary circuits. This modular structure results in easier design and implementation procedures in VLSI fabrication. the double‐sampling concept is applied to the introduced modular blocks, which is essentially needed in high‐frequency applications. A comparison with similar published work available in the literature is presented and illustrative examples are given.

Design of selective lowpass sampled‐data and digital filters exhibiting equiripple amplitude and phase error characteristics

AbstractA method is presented for the design of reciprocal reactant sampled‐data and digital filters exhibiting equiripple passband and stopband amplitude characteristics and approximating a linear phase characteristic such that the phase error response is equiripple too. the passband amplitude characteristic approximates unity transmission and the stopband amplitude characteristic approximates zero. Odd‐ and even‐degree cases are considered separately. the stopband amplitude response is controlled by an arbitrary number of finite transmission zeros together with two (one) zeros at infinity for even (odd) transfer functions. All the available degrees of freedom are used for controlling the filter performances. Thus the resulting solutions are selective and have good amplitude and phase characteristics. A comparison between our method and a recently published method shows that this approach has higher stopband loss and smaller phase error ripple with wider bandwidth.

Synthesis of general asymmetric singly- and doubly-terminated cross-coupled filters

A new synthesis is given for the realization of cross-coupled filters in the general asymmetric case, which includes singly terminated filters useful in the design of contiguous multiplexers. The result is obtained by formation of the 2-port transfer matrix of the network, enabling circuit element extractions to be performed from both input and output ports, including the direct extraction of cross-couplings. An example is presented of an 8th degree singly-terminated filter having finite frequency and real axis transmission zeros.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

CMOS continuous-time current-mode filters for high-frequency applications

Design considerations for high-frequency CMOS continuous-time current-mode filters are presented. The basic building block is a differential current integrator with its gain constant set by a small-signal transconductance and a gate capacitance. A prototype fifth-order low-pass ladder filter implemented in a standard digital 2 mu m n-well CMOS process achieved a -3 dB cutoff frequency (f/sub 0/) of 42 MHz; f/sub 0/ was tunable from 24 to 42 MHZ by varying a reference bias current from 50 to 150 mu A. Using a single 5 V power supply with a nominal reference current of 100 mu A, the five-pole filter dissipated 25.5 mW. The active filter area was 0.056 mm/sup 2//pole. With the minimum input signal defined as the input-referred noise integrated over a 40 MHz bandwidth, and the maximum input signal defined at the 1% total intermodulation distortion (TIMD) level, the measured dynamic range was 69 dB. A third-order elliptic low-pass ladder filter was also integrated in the 2 mu m n-well CMOS process to verify the implementation of finite transmission zeros. >

Asymmetric bandpass filter using a ceramic structure

A ceramic bandpass filter with increased selectivity on the lower side of the passband is presented. One application is the receive filter of a mobile radio transceiver operating in the 1.8-GHz bands. Finite transmission zeros have been introduced by using a network with additional cross couplings. The circuit was constructed with four coaxial ceramic resonators capacitively coupled using a microstrip PCB. For a 75-MHz passband filter, a stopband attenuation of 37 dB was attained at 20-MHz offset from the passband. A midband insertion loss of 1.2 dB and bandedge loss of 3 dB were achieved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Deadbeat control of linear multivariable generalized state-space systems

The classic idea of deadbeat control is extended to linear multivariable discrete-time generalized state-space systems using algebraic methods. The asymptotic properties of the linear quadratic regulator theory are used to obtain the classes of deadbeat controllers using stabilizing full semistate feedback. The solution is constructed from a 'cheap control' problem. Both semistate and output deadbeat control laws are considered. The main design criteria are to drive the semistate and/or outputs of the system to zero in minimum time and that the closed-loop system be internally stable. Unique properties of these types of control laws are discussed. For semistate deadbeat control, all the (dynamic) poles including the ones at infinity are moved to the origin, whereas for output deadbeat, some of the finite transmission zeros are canceled. Numerically reliable algorithms are developed to solve both problems. >

Multiple-real-pole and multiple-critical-pole maximally flat RC active lowpass filters with sharp cut-off

Recently, an attempt has been made to design a multiple-real-pole/multiple-critical-pole maximally flat RC-active filter with sharp cut-off by including a multiple pair of concident jω-axis zeros (Wei and Chien 1985). This design technique unfortunately has two major drawbacks, i.e. (i) the passband response does not truly satisfy the maximally flat criterion with a consequent large deviation from the desired no-loss response and (ii) there is a limitation on the realizable number of third-order blocks with finite transmission zeros. A new design technique is therefore proposed here whereby all the aforementioned undesirable features are eliminated. The technique is also extended to cover the case of prescribed finite transmission zeros. Hence, this new technique offers a multiple-real-pole/multiple-critical-pole maximally flat lowpass RC-active filter with a sharp cut-off and also effective suppression of noise at prescribed frequencies.