Microwave Active Filters Research Articles

Radiation and temperature effects on the operation of microwave active filters

A methodology for computer-simulated design of active microwave filters, either all- or band-pass ones, was shown previously (I.A. El-Shahat and co-workers, Int. AMSE Conf., Rabat, Morocco, Vol. 1, Oct. 1995, pp. 265–274; Microwaves RFJ. (Nov. 1995; (in press)). In this paper, we illustrate the effects of radiation and temperature on the operation of such filters. In general, gamma-exposure of the GaAs FETs (MESFETs) up to 80 Mrads leads the gain of the filters to decrease. In the ideal and optimal cases of both filters the decrease of gain is negligible. Also, when the device temperature increases from -50 to 150°C, the gain is decreased in both cases; ideal and optimal.

MMIC-simulated inductors using compensated gyrators

A design methodology for simulated MMIC inductors is presented. While audio-frequency realizations of such circuits are built using relatively imperfection-free gyrators terminated in lossless capacitors, our microwave implementation necessarily allows the specification of tables of s-parameters for the transistors in the network, along with detailed models for the passive MMIC components. Our method, in computer simulation, has realized a 5-nH inductance over 1.5–2.5 GHz by terminating a nonideal transistor gyrator in a special compensating RLC one port, which itself may be designed using readily available CAD tools. Such simulated inductors have important application in microwave active filters. © 1997 John Wiley & Sons, Inc. Int J Microwave Millimeter-Wave CAE 7: 241–249, 1997

Editorial

International Journal of Microwave and Millimeter-Wave Computer-Aided EngineeringVolume 7, Issue 3 p. 207-207 Editorial K. C. Gupta, K. C. GuptaSearch for more papers by this author K. C. Gupta, K. C. GuptaSearch for more papers by this author First published: 07 December 1998 https://doi.org/10.1002/(SICI)1522-6301(199705)7:3<207::AID-MMCE1>3.0.CO;2-LAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue3Special Issue: CAD of Microwave Passive and Active Filters: Part IIMay 1997Pages 207-207 RelatedInformation

Microwave active filter in integrated waveguide technology

A new configuration for the microwave active filter based on integrated waveguide technology is described. A filtering structure is formed by an evanescent mode rectangular waveguide loaded with dielectric slabs. A Gunn diode is used to compensate for dissipative losses. The transmission matrix model has been used to determine a configuration of the microwave active filter and complex admittance of the active element providing full compensation of insertion loss. The measured results have confirmed theoretical predictions.

Microwave channelized active filters-a new modular approach to achieving compactness and high selectivity

The new class of microwave active filters being presented offers a convenient way to realize miniature filter circuits with sharp passband-to-stopband transitions. The approach, which lends itself to a broad range of narrowband and wideband filtering applications, involves parallel connections of frequency-selective, unilateral network branches that contain both passive and active subcircuits. Highly selective filtering action derives from controlled interferences among branch signal components. Attributes of the new technique include unconditional circuit stability, tolerance for large passive-circuit-element losses, practicability of narrowband lumped-element configurations, graceful performance degradation with active element parameter changes, and the advantage of module-based procedures for design and implementation. The broad applicability of the new approach is illustrated with three experimental demonstration circuits that employ off-the-shelf MMIC amplifier chips. The circuits comprise a 10-GHz notch filter of one quarter percent bandwidth, a 10-GHz bandpass filter of two percent bandwidth, and a 7.5-GHz lowpass filter.

An NIC‐based negative capacitance circuit for microwave active filters (invited article)

AbstractThis article presents a method for synthesizing a negative capacitance in MMIC technology, and extends our earlier work (S. E. Sussman‐Fort, Int. J. MIMICAE, Vol. 4, No. 2, April 1994, pp. 130‐139) involving the realization of MMIC negative resistance. As before, we employ a classical negative impedance converter (NIC) that has been terminated in an RLC one port specially designed to compensate for the parasitics of the active and passive elements. We argue that, in most cases, this one port will be physically realizable, and we provide numerical results for the synthesis which supports this idea. The procedure is demonstrated in computer simulation for a four‐transistor MMIC network which achieves a virtually pure capacitance of ‐5 pF over 1.5‐2.5 GHz. Such NIC‐based negative capacitance (and resistance) has potential application in the design of microwave gyrators and active filters. © 1995 John Wiley &amp; Sons, Inc.

Miniature microwave filters for communication systems

This paper presents new developments in miniature integrated microwave filters suitable for application in mobile communication handsets, wireless LAN's and microwave fixed links. Recent measured results for active microwave filters are presented with emphasis on their nonlinear behavior. The use of high permittivity ceramic substrates in parallel plate TEM mode stripline filters is described and recent measured results are presented for a prototype 2-GHz filter occupying a volume of 0.5-cubic centimeters. E-Plane filters for millimeter wave applications are discussed and measured results are presented for a novel E-Plane filter with asymmetric frequency response which was realized in a planar structure. Finally, a new type of ceramic loaded E-Plane filter is proposed. >

MMIC active bandpass filters using varactor-tuned negative resistance elements

This paper describes techniques for realizing microwave active filters using single transistor active resonators in a negative resistance configuration, The negative resistance topologies for both bipolar (AlGaAs/GaAs HBT) and FET (MESFET or HEMT) devices are studied and compared. The essence of the technique is that the input reactance of the transistor circuit resonates with an external capacitor or inductor, whilst the negative resistance is used to compensate for the losses in the resonator. It is shown that the FET device is ideally suited for this application as it can have a varactor-controlled negative resistance component. Three-stage and two-stage monolithic varactor-tuned bandpass filters have been demonstrated using this technique. The measured response of the three-stage filter exhibits a 120 MHz 3 dB-bandwidth centered on 2.3 GHz, 0 dB insertion loss with only /spl plusmn/0.1 dB ripple in the pass-band, up to 100 dB of stop-band attenuation at low frequencies, and over 50 dB of rejection up to 6 GHz. The two-stage filter exhibits a 400 MHz 3 dB-bandwidth centered on 4.7 GHz, with tunable insertion gain and only /spl plusmn/0.1 dB ripple in the pass-band.

Coplanar waveguide active bandpass filter

A novel microwave active bandpass filter has been designed in coplanar waveguide. The approach uses a GaAs FET to link two end-coupled resonators. The realised active filter not only compensates for the losses as compared to a passive filter but also provides an overall gain of 17.54 dB. Flexibility in tuning the filter response through the bias voltage and its superior performance at the harmonics over the passive filters are among the advantages of the design.

Active microwave filters with noise performance considerations

Active microwave filters offer a unique solution for certain filtering problems in modern microwave integrated circuit applications. A number of authors have reported novel active filter topologies in this connection; however, noise considerations for these exotic designs have seldom been addressed, and only Bonetti and Williams (1990, 1992) have provided actual reliable repeatable measured noise data across a band of frequencies. The main objective of this paper is to present a precision computer-oriented technique to accurately predict and quantify the noise performance of various active microwave filter realizations. Experimental examples are presented which validate the computer-oriented simulation methodology. Noise performance results are presented for a representative realization of each class of active microwave filter considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An NIC‐based negative resistance circuit for microwave active filters

AbstractThis article presents a method for synthesizing a negative resistance in MMIC technology. The circuit employed is a classical negative impedance converter (NIC) that has been terminated in an RLC one‐port specially designed to compensate for the parasitics of the active and passive elements. The procedure, which effectively translates a nonideal NIC design task into a well‐defined one‐port synthesis problem, is demonstrated in computer simulation for a four‐transistor MMIC network which achieves a purely real input resistance of −100 Ω over 1.5–2.5 GHz. An important application for NIC‐based circuits of this type is in the design of microwave active filters. © 1994 John Wiley &amp; Sons, Inc.

Microwave active filter using GaAs monolithic floating active inductor

AbstractA broadband tunable microwave floating active inductor is proposed. Its application in the microwave active filter is presented. The design technique is to replace the passive inductor in the conventional LC ladder filter by the proposed floating active inductor. These active filters can, therefore, be implemented in full MMIC form. © 1992 John Wiley &amp; Sons, Inc.

A varactor-tuned active microwave bandpass filter

Traditionally, microwave filters have been implemented as passive networks of waveguide, transmission-line, or discrete lumped elements. More recently, microwave active filters have also been realized. A microwave high Q-active bandpass filter is presented. using a varactor diode for tuning, and an active component giving a substantial increase in Q of the resonant sections of filter. High-Q filter elements offer low-filter insertion loss and also yield sharp passband corners, which cannot be achieved by lossy filter and amplifier combination.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design concepts of a novel microwave active filter

A novel microwave active bandpass filter structure, using a combination of microstrip line resonators and FETs, is described. The resulting filter not only produces positive gain but also has good performance regarding sharpness of skirts, rejection, and input and output return losses. Capability of constructing wider bandwidth and its superior performance at harmonic band frequencies over an end-coupled filter structure are among advantages of this design.

CAD technique for designing microwave transistor active filters

A CAD method for designing microwave active filters, based on an extension of the simplified real frequency technique, is presented. This approach is analogous to the design of the matching networks in microwave amplifiers: the filter is developed by cascading active devices with passive two-ports which have a particular form of the transfer function. The potential of the method is illustrated by a computer simulated design of bandpass active filters.

A realization of a GaAs FET microwave active filter

A methodology for microwave active filter design has been presented by this author (see ibid., vol.37, no.9, p.1418-24, 1989). The present work serves to verify aspects of this design approach. A practical implementation of a network discussed in that work is given. First, an ideal preliminary design for a second-order bandpass filter is obtained. Next, the nonideal effects of the active devices and the lossy reactive elements are introduced, and then optimization is used to obtain the final design. Finally, the filter is constructed and tested. The measured response is found to agree quite closely with the design specifications. The filter section is constructed in hybrid form with lumped components, and uses two NEC 900100 GaAs FETs. The prototype accurately realizes a second-degree bandpass response with a center frequency of 6 GHz and a pole q of 2.5. >

Microwave active filters based on coupled negative resistance method

A novel coupled negative resistance method for building a microwave active bandpass filter is introduced. Based on this method, four microstrip line end-coupled filters were built. Two are fixed-frequency one-pole and two-pole filters, and two are tunable one-pole and two-pole filters. In order to broaden the bandwidth of the end-coupled filter, a modified end-coupled structure is proposed. Using the modified structure, an active filter with a bandwidth up to 7.5% was built. All of the filters show significant passband performance improvement. Specifically, the passband bandwidth was broadened by a factor of 5 to 20.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Narrowband planar microwave active filter

A new circuit design for narrowband microwave active filters is presented in the letter. By increasing the tank circuit unloaded Q-value an ideal one-section bandpass filter is realised.

Design concepts for microwave GaAs FET active filters

A comprehensive history of microwave active filter development to date is given. A design methodology is presented for the realization of precision broadband filters in the face of problems such as the nonideal behavior of microwave GaAs FETs and the low Q and related parasitic effects of monolithic-microwave-integrated-circuit (MMIC) inductors and capacitors. The feasibility of this approach is illustrated by the computer-simulated design of a cascadable, second-order microwave bandpass filter. >

Microwave Active Filters Based on Transversal and Recursive Principles

Transferal and recursive filter concepts, normally associated with discrete-time applications, are adapted for implementation in the microwave frequency range. Principal focus is on microwave active filter designs that permit realization of wide bandwidths, with microwave transistors used as active elements. A transversal-type and a recursive-type experimental filter, both of which exhibit 9-15-GHz bandpass responses, serve to illustrate aspects of physical implementation, while offering a convenient basis for comparing the two different approaches.