ES2246124A1 - Active step-band filter structure for filtering sections of interference in e.g. transmission line, has interference sections separated by insulating stages, where constructive interference is maintained in passage band - Google Patents
Active step-band filter structure for filtering sections of interference in e.g. transmission line, has interference sections separated by insulating stages, where constructive interference is maintained in passage bandInfo
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- 238000004891 communication Methods 0.000 abstract description 4
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- 230000002238 attenuated effect Effects 0.000 description 6
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- 230000015572 biosynthetic process Effects 0.000 description 3
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Abstract
Description
Estructura filtrante activa paso-banda mediante secciones de interferencia con líneas de transmisión conectadas en paralelo.Active filter structure pass-band through interference sections with Transmission lines connected in parallel.
La presente invención queda enmarcada en el sector técnico de las tecnologías de radiofrecuencia, y más concretamente en las técnicas de diseño de filtros activos en las bandas de microondas y milimétricas.The present invention is framed in the technical sector of radio frequency technologies, and more specifically in the design techniques of active filters in microwave and millimeter bands.
El creciente auge de los sistemas de comunicaciones inalámbricos y radar de banda ancha, así como la progresiva tendencia hacia la construcción de sistemas integrados multifunción, está propiciando que uno de los aspectos clave a cuidar en el diseño de cualquier subsistema de radiofrecuencia sea el tamaño físico del circuito resultante.The growing boom of systems wireless communications and broadband radar, as well as the progressive trend towards the construction of integrated systems multifunction, is leading one of the key aspects to take care of the design of any radio frequency subsystem the physical size of the resulting circuit.
En el caso de estructuras filtrantes activas, resulta indispensable asegurar que dicha reducción de tamaño no vaya acompañada de una disminución significativa de la selectividad de la respuesta en frecuencia del filtro. Además, se ha de procurar que tales estructuras posean otras prestaciones aparte de una alta selectividad filtrante en un reducido espacio, como son bajas pérdidas de transmisión, bajo ruido y estabilidad incondicional.In the case of active filter structures, it is essential to ensure that such size reduction does not be accompanied by a significant decrease in selectivity of the frequency response of the filter. In addition, care must be taken that such structures possess other benefits apart from a high filter selectivity in a small space, as they are low Transmission losses, low noise and unconditional stability.
Todo lo anterior viene a justificar la progresiva demanda de filtros activos en microondas con cada vez más altas prestaciones. Efectivamente, las técnicas de diseño tradicionales de esta clase de circuitos parecen incapaces de abordar todas estas nuevas exigencias: la síntesis de respuestas altamente selectivas desemboca en circuitos de excesivo tamaño en el caso de "filtros activos consistentes en la conexión en cascada de etapas pasivas y activas", y en altos niveles de ruido en el caso de "filtros con resonadores activos".All of the above comes to justify the progressive demand for active microwave filters with increasingly high performance. Indeed, the traditional design techniques of this kind of circuits seem incapable of addressing all these new requirements: the synthesis of highly selective responses leads to circuits of excessive size in the case of "active filters consisting of cascading passive stages and active " , and at high noise levels in the case of " filters with active resonators " .
En los últimos años, una de las más novedosas tendencias en el diseño de filtros activos de radiofrecuencia consiste en extrapolar a rangos de microondas las técnicas tradicionales de diseño de filtros digitales. De esta forma surgen los "filtros activos recursivos" y "filtros activos transversales" para alta frecuencia, estructuras que tienen en común el empleo de varios caminos de señal para la síntesis de respuestas altamente selectivas. En el caso de las estructuras recursivos, la característica de filtrado global se obtiene mediante la interferencia en fase de una rama directa y varias ramas realimentadas que procesan las distintas componentes de señal en sentidos opuestos. En las configuraciones transversales, todas las ramas presentan el mismo sentido de procesado, que bien puede consistir en un simple retardo y escalado constante en frecuencia, o ser más complejo. A pesar de las mayores prestaciones de esta clase de configuraciones filtrantes activas frente a las primeras, todavía existen problemas de inestabilidad potencial en el caso de los filtros recursivos, y de excesivo tamaño del circuito resultante para la síntesis de respuestas con gran selectividad cuando se emplean estructuras transversales.In recent years, one of the most innovative trends in the design of active radiofrequency filters is to extrapolate traditional digital filter design techniques to microwave ranges. In this way, the "recursive active filters" and "transverse active filters" for high frequency arise, structures that have in common the use of several signal paths for the synthesis of highly selective responses. In the case of recursive structures, the overall filtering characteristic is obtained by the phase interference of a direct branch and several feedback branches that process the different signal components in opposite directions. In cross-sectional configurations, all branches have the same sense of processing, which may well consist of a simple delay and constant frequency scaling, or be more complex. Despite the higher performance of this class of active filter configurations compared to the first, there are still problems of potential instability in the case of recursive filters, and excessive resulting circuit size for the synthesis of responses with great selectivity when used cross structures.
Con el fin de acabar con los problemas de tamaño de los filtros transversales, al mismo tiempo que se mantienen sus buenas prestaciones en cuanto a ruido y estabilidad, surgen recientemente los "filtros canalizados activos" como una generalización de los primeros. De igual forma que las configuraciones transversales, las estructuras canalizadas están constituidas por varias ramas o canales que procesan las distintas componentes de señal en un único sentido. Ahora bien, mediante el empleo de un procesado más complicado en cada canal y haciendo uso de una conexión más sencilla de todas las ramas del filtro, generalmente en paralelo, resulta posible sintetizar respuestas de gran selectividad empleando a lo sumo dos o tres canales. Por otro lado, esto supone un aumento notable de la complejidad de los procedimientos de diseño para este tipo de estructuras filtrantes.In order to end the cross-sectional size problems, while maintaining their good performance in terms of noise and stability, "active ducted filters" have recently emerged as a generalization of the former. In the same way as the transversal configurations, the channeled structures are constituted by several branches or channels that process the different signal components in a single direction. However, by using a more complicated processing in each channel and making use of a simpler connection of all branches of the filter, generally in parallel, it is possible to synthesize highly selective responses using at most two or three channels. On the other hand, this represents a significant increase in the complexity of the design procedures for this type of filter structures.
La presente invención supone una alternativa sencilla para el diseño de filtros activos en circuitos de reducido tamaño, y con buenas propiedades de ruido, estabilidad y ganancia. Esto se realiza mediante el empleo de novedosas secciones de interferencia basadas en pares de tramos de línea de transmisión conectados en paralelo.The present invention is an alternative simple for the design of active filters in reduced circuits size, and with good noise, stability and gain properties. This is done through the use of new sections of interference based on pairs of transmission line sections connected in parallel.
La presente invención consiste en una estructura filtrante activa paso-banda en radiofrecuencia, microondas o en bandas milimétricas de gran selectividad mediante el empleo de secciones de interferencia basadas en pares de tramos de línea de transmisión conectados en paralelo. Se entiende por respuesta de gran selectividad aquella cuya función de transferencia presenta una transición muy abrupta entre banda de paso y atenuada, así como un fuerte rechazo fuera de banda.The present invention consists of a structure active pass-band radio frequency filter, microwave or in highly selective millimeter bands using the use of interference sections based on pairs of sections of Transmission line connected in parallel. It is understood by highly selective response that whose transfer function it presents a very abrupt transition between pass and attenuated band, as well as a strong rejection out of band.
La estructura filtrante está constituida por la conexión en cascada de un filtro pasivo (1) y una etapa de interferencia activa (2). El filtro pasivo constituye una aproximación de bajo orden a la respuesta global altamente selectiva que se desea conseguir, lo que significa que la banda de paso de la respuesta global vendrá básicamente definida por la del filtro pasivo. La función de la etapa de interferencia es incrementar la selectividad del filtro pasivo mediante la generación de interferencias destructivas en forma de ceros de transmisión fuera de la banda de paso del filtro. De esta forma, resulta posible disminuir en gran medida la transición entre banda de paso y atenuada, así como el rechazo fuera de banda de paso, obteniéndose por tanto una respuesta filtrante altamente selectiva.The filter structure is constituted by the cascading of a passive filter (1) and a stage of active interference (2). The passive filter constitutes a Low order approach to the global response highly selective that you want to achieve, which means that the band of The overall response step will basically be defined by the passive filter The function of the interference stage is increase passive filter selectivity through generation of destructive interference in the form of transmission zeros outside the pass band of the filter. In this way, it turns out possible to greatly reduce the transition between passband and attenuated, as well as the out-of-band rejection, obtaining therefore a highly selective filter response.
Las prestaciones anteriores se consiguen mediante el empleo de novedosas secciones de interferencia consistentes en pares de tramos de línea de transmisión conectados en paralelo (4,6). Dichas secciones generan múltiples ceros de transmisión fuera de la banda de paso del filtro pasivo, manteniendo una interferencia totalmente constructiva en dicha banda. Para ello, resulta necesario que la diferencia entre las longitudes de onda eléctricas de los tramos de línea de transmisión (7,8) que constituyen las secciones de interferencia sea múltiplo de 2\pi a la frecuencia central de la respuesta del filtro. A medida que tal diferencia de longitudes es mayor (4\pi, 6\pi,...) resulta posible sintetizar respuestas de banda más estrecha y con una transición más abrupta entre banda de paso y atenuada.The above benefits are achieved through the use of novel interference sections consisting of pairs of transmission line sections connected in parallel (4.6). These sections generate multiple transmission zeros outside of the passive band of the passive filter, maintaining a totally constructive interference in said band. For it, it is necessary that the difference between wavelengths electric of the transmission line sections (7,8) that constitute the interference sections be a multiple of 2 \ pi a the central frequency of the filter response. As such length difference is greater (4 \ pi, 6 \ pi, ...) results possible to synthesize narrower band responses and with a more abrupt transition between pass band and attenuated.
Dentro de la etapa de interferencia es posible utilizar secciones de interferencia similares (misma diferencia entre longitudes de onda eléctricas) o distintas, en función de las características concretas deseadas en la respuesta filtrante global. Es decir, la diferencia entre las longitudes de onda de los tramos de línea para las diversas secciones de interferencia es distinta. De igual forma, resulta necesario el empleo de etapas aisladoras (3,5) conectadas entre las distintas secciones de interferencia para garantizar una buena adaptación entre los distintos elementos de la estructura filtrante, además de asegurar un comportamiento unilateral del filtro activo. Cuando las etapas aisladoras se implementan con amplificadores de alta ganancia y gran aislamiento en el sentido salida-entrada, se añade ganancia a la respuesta global. Se considera por alta ganancia aquella superior a 10 dB, y por gran aislamiento en el sentido salida-entrada del amplificador aquel superior a 25 dB. Si las etapas aisladoras se realizan mediante circuladores, se garantiza el comportamiento unilateral de la estructura filtrante completa con bajas pérdidas de transmisión.Within the interference stage it is possible use similar interference sections (same difference between electric wavelengths) or different, depending on the specific characteristics desired in the global filter response. That is, the difference between the wavelengths of the sections Line for the various interference sections is different. Similarly, the use of insulating stages is necessary (3.5) connected between the different interference sections to ensure a good adaptation between the different elements of the filter structure, in addition to ensuring a behavior unilateral active filter. When the insulating stages are implemented with high gain and high isolation amplifiers in the exit-entry direction, gain is added to the global response High gain is considered to be higher than 10 dB, and for great isolation in the sense amplifier output-input that exceeds 25 dB If the insulating stages are carried out using circulators, guarantees the unilateral behavior of the filter structure Complete with low transmission losses.
La presente invención es especialmente adecuada para el diseño y desarrollo sencillo de estructuras filtrantes activas con gran selectividad de banda ancha y estrecha, con alta ganancia y estabilidad incondicional.The present invention is especially suitable. for the simple design and development of filter structures active with high selectivity broadband and narrow, with high Unconditional gain and stability.
\bullet Figura 1 es el diagrama de bloques conceptual de la presente invención, constituido por la conexión en cascada de un filtro pasivo (1) y una etapa de interferencia activa (2). A su vez, la etapa de interferencia (2) está formada por secciones de interferencia (4 y 6) separadas mediante etapas aisladoras (3 y 5).Figure 1 is the block diagram conceptual of the present invention, constituted by the connection in cascade of a passive filter (1) and an active interference stage (2). In turn, the interference stage (2) is formed by interference sections (4 and 6) separated by stages insulators (3 and 5).
\bullet Figura 2 muestra la implementación circuital de la sección de interferencia, consistente en la conexión en paralelo de dos tramos de línea de transmisión de distintas longitudes (7 y 8).Figure 2 shows the implementation circuit of the interference section, consisting of the parallel connection of two sections of transmission line different lengths (7 and 8).
\bullet Figura 3 es una gráfica que muestra la comparación de las respuestas normalizadas de transmisión de potencia medidas para sendos prototipos de filtro pasivo (9) y estructura filtrante activa total (10). Se representa en el eje Y la amplitud en decibelios, y en el eje X la frecuencia normalizada respecto a la frecuencia central del filtro.Figure 3 is a graph showing the comparison of standardized transmission responses of power measures for two passive filter prototypes (9) and Total active filter structure (10). It is represented on the Y axis the amplitude in decibels, and in the X axis the normalized frequency with respect to the central frequency of the filter.
La estructura filtrante activa se encuentra formada por la conexión en cascada de un filtro pasivo (1) y una etapa de interferencia activa (2).The active filter structure is found formed by the cascading of a passive filter (1) and a active interference stage (2).
El filtro pasivo (1) se diseña como una aproximación de bajo orden de la respuesta total altamente selectiva que se pretende sintetizar con la estructura completa. La banda de paso global vendrá, por tanto, definida por la del filtro pasivo. Para su realización final se opta por una configuración de líneas acopladas que sintetiza una respuesta tipo Butterworth de segundo orden en tecnología planar.The passive filter (1) is designed as a low order approximation of the total response highly selective that is intended to synthesize with the complete structure. The global pass band will therefore be defined by that of the filter passive. For its final realization, a configuration of coupled lines that synthesizes a Butterworth type response of Second order in planar technology.
La etapa de interferencia activa (2) se encarga de incrementar la selectividad de la respuesta filtrante definida por el filtro pasivo (1), mediante la generación de interferencias destructivas fuera de la banda de paso que disminuyen la transición entre banda de paso y atenuada, así como el rechazo fuera de banda.The active interference stage (2) takes care to increase the selectivity of the defined filter response by the passive filter (1), by generating interference destructive outside the pass band that slow the transition between passband and attenuated, as well as rejection outside band.
La etapa de interferencia activa (2) incluye dos secciones interferentes (4 y 6) basadas en tramos de línea de transmisión en paralelo (7 y 8). La primera sección (4) presenta un diferencia entre longitudes eléctricas de los tramos de línea a la frecuencia central de valor 2\pi, lo que permite incrementar el rechazo fuera de banda a frecuencias alejadas de la banda de paso. La segunda sección de interferencia (6) presenta una diferencia entre longitudes de valor 4\pi, con el fin de aumentar el rechazo fuera de banda a frecuencias muy próximas a la banda de paso, así como la velocidad de transición entre banda de paso y atenuada. Esto permite conseguir un aumento notable de la selectividad filtrante en todo el rango de frecuencias fuera de la banda de paso del filtro.The active interference stage (2) includes two interfering sections (4 and 6) based on line sections of parallel transmission (7 and 8). The first section (4) presents a difference between electrical lengths of the sections of line to the central frequency of value 2 \ pi, which allows to increase the out-of-band rejection at frequencies far from the pass band. The second interference section (6) presents a difference between lengths of value 4 \ pi, in order to increase rejection out of band at frequencies very close to the pass band as well as the transition speed between pass band and attenuated. This allows to achieve a notable increase in filter selectivity in the entire frequency range outside the pass band of the filter.
La etapa de interferencia activa (2) incorpora también dos etapas aisladoras (3 y 5) situadas entre filtro pasivo-primera sección de interferencia (3), y primera sección de interferencia- segunda sección de interferencia (5), respectivamente. Su función básica es proporcionar una buena adaptación entre los distintos elementos del filtro activo, y garantizar un comportamiento unilateral de la estructura completa. Concretamente, las etapas aisladoras (3) y (5) se implementan mediante un amplificador alta ganancia y aislamiento moderado (20 dB) seguido de una etapa atenuadora de 6 dB. Esto posibilita la obtención de una ganancia de potencia en transmisión en toda la banda de paso de la estructura filtrante.The active interference stage (2) incorporates also two insulating stages (3 and 5) located between filter passive-first interference section (3), and first interference section - second interference section (5), respectively. Its basic function is to provide a good adaptation between the different elements of the active filter, and guarantee unilateral behavior of the complete structure. Specifically, the insulating stages (3) and (5) are implemented using a high gain amplifier and moderate isolation (20 dB) followed by a 6 dB attenuator stage. This enables the obtaining a gain in transmission power throughout the pass band of the filter structure.
Se puede verificar el notable aumento de selectividad en toda la banda atenuada gracias al empleo de la etapa de interferencia (Fig. 3).The remarkable increase of selectivity throughout the attenuated band thanks to the use of interference stage (Fig. 3).
La presente invención presenta una potencial aplicación en el sector de Tecnologías de la Radiofrecuencia. Particularmente, resulta de gran importancia para el diseño y desarrollo de estructuras filtrantes altamente selectivas para los equipos de alta frecuencia de sistemas de comunicaciones inalámbricas de banda ancha, comunicaciones vía satélite y radar.The present invention has a potential Application in the Radio Frequency Technologies sector. Particularly, it is of great importance for the design and development of highly selective filter structures for high frequency equipment communications systems wireless broadband, satellite communications and Radar.
1. C. Rauscher, "Microwave Active Filters Based on Transversal and Recursive Principles", IEEE Transactions on Microwave Theory and Techniques, vol. 33, pp. 1350-1360, December 1985.1. C. Rauscher , "Microwave Active Filters Based on Transversal and Recursive Principles", IEEE Transactions on Microwave Theory and Techniques, vol. 33, pp. 1350-1360, December 1985 .
2. C. Rauscher, "Microwave Channelized Active Filters: A New Modular Approach to Achieving Compactness and High Selectivity", IEEE Transactions on Microwave Theory and Techniques, vol. 44, pp. 122-132, January 1996.2. C. Rauscher , "Microwave Channelized Active Filters: A New Modular Approach to Achieving Compactness and High Selectivity", IEEE Transactions on Microwave Theory and Techniques, vol. 44, pp. 122-132, January 1996 .
3. K W. Tarn et al, "MMIC Active Filter with Tuned Transversal Element", IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, vol. 45, pp. 632-634, May 1998.3. K W. Tarn et al, "MMIC Active Filter with Tuned Transversal Element", IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, vol. 45, pp. 632-634, May 1998 .
4. R. Gómez-García et al, "On the Design of High-Linear and Low-Noise Two-Branch Channelized Active Bandpass Filters", IEEE Transactions on Circuits and Systems 11: Analog and Digital Signal Processing, vol. 50, pp. 695-704, October 2003.4. R. Gómez-García et al, "On the Design of High-Linear and Low-Noise Two-Branch Channelized Active Bandpass Filters", IEEE Transactions on Circuits and Systems 11: Analog and Digital Signal Processing, vol. 50, pp. 695-704, October 2003 .
5. C. Rauscher, "Microwave Recursive Filters", U.S. Patent 4.661.789.5. C. Rauscher , "Microwave Recursive Filters", US Patent 4,661,789.
6. Kikuo Wakino et al, "Parallel Connection Multistage Bandpass Filter", U.S. Patent 5.097.236.6. Kikuo Wakino et al, "Parallel Connection Multistage Bandpass Filter", US Patent 5,097,236.
7. Richard C. Edwards., "Filter System with Controlled Amplitude in Stopband or Passband", U.S. Patent 5.180.999.7. Richard C. Edwards ., "Filter System with Controlled Amplitude in Stopband or Passband", US Patent 5,180,999.
8. C. Rauscher, "Limited Bandwidth Microwave Filter", U.S. Patent 5.339.057.8. C. Rauscher , "Limited Bandwidth Microwave Filter", US Patent 5,339,057.
9. Richard M. Hahn, "Cancellation Technique for Bandpass Filters Using a Narrowband Network Having Optimally Coupled and Overcoupled Filters", U.S. Patent 5.721.518.9. Richard M. Hahn , "Cancellation Technique for Bandpass Filters Using a Narrowband Network Having Optimally Coupled and Overcoupled Filters", US Patent 5,721,518.
10. Norio Nakajima et al, "High-Frequency Composite Components Comprising First and Second Circuits Connected in Parallel for Multifrequency Sistems", U.S. Patent 5.815.052.10. Norio Nakajima et al, "High-Frequency Composite Components Comprising First and Second Circuits Connected in Parallel for Multifrequency Sistems", US Patent 5,815,052.
11. C. Rauscher, "Microwave Channelized Bandpass Filter Having Two Channels", U.S. Patent 6.107.898.11. C. Rauscher , "Microwave Channelized Bandpass Filter Having Two Channels", US Patent 6,107,898.
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Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| ES200400377A ES2246124B2 (en) | 2004-02-17 | 2004-02-17 | ACTIVE FILTER STRUCTURE STEP-BAND THROUGH INTERFERENCE SECTIONS WITH TRANSMISSION LINES CONNECTED IN PARALLEL. |
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| Application Number | Priority Date | Filing Date | Title |
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| ES200400377A ES2246124B2 (en) | 2004-02-17 | 2004-02-17 | ACTIVE FILTER STRUCTURE STEP-BAND THROUGH INTERFERENCE SECTIONS WITH TRANSMISSION LINES CONNECTED IN PARALLEL. |
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| ES2246124A1 true ES2246124A1 (en) | 2006-02-01 |
| ES2246124B2 ES2246124B2 (en) | 2006-08-01 |
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| ES200400377A Expired - Fee Related ES2246124B2 (en) | 2004-02-17 | 2004-02-17 | ACTIVE FILTER STRUCTURE STEP-BAND THROUGH INTERFERENCE SECTIONS WITH TRANSMISSION LINES CONNECTED IN PARALLEL. |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55104103A (en) * | 1979-02-02 | 1980-08-09 | Hitachi Ltd | Microstrip bandpass filter |
| US5339057A (en) * | 1993-02-26 | 1994-08-16 | The United States Of America As Represented By The Secretary Of The Navy | Limited bandwidth microwave filter |
| JP2003124706A (en) * | 2001-10-12 | 2003-04-25 | Toyota Central Res & Dev Lab Inc | Band pass filter, module card and radio equipment |
| JP2003258667A (en) * | 2002-02-26 | 2003-09-12 | Murata Mfg Co Ltd | Filter circuit and tuner device using the same |
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2004
- 2004-02-17 ES ES200400377A patent/ES2246124B2/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55104103A (en) * | 1979-02-02 | 1980-08-09 | Hitachi Ltd | Microstrip bandpass filter |
| US5339057A (en) * | 1993-02-26 | 1994-08-16 | The United States Of America As Represented By The Secretary Of The Navy | Limited bandwidth microwave filter |
| JP2003124706A (en) * | 2001-10-12 | 2003-04-25 | Toyota Central Res & Dev Lab Inc | Band pass filter, module card and radio equipment |
| JP2003258667A (en) * | 2002-02-26 | 2003-09-12 | Murata Mfg Co Ltd | Filter circuit and tuner device using the same |
Non-Patent Citations (6)
| Title |
|---|
| Base de Datos PAJ en EPOQUE & JP 55104103 A (HITACHI LTD) 09.08.1980, resumen; figuras. * |
| Base de Datos PAJ en EPOQUE: & JP 2003124706 A (TOYOTA CHUO KENKYUSHO KK) 25.04.2003, resumen; figuras. * |
| Base de Datos PAJ en EPOQUE: & JP 2003258667 A (MURATA MANUFACTURING CO) 12.09.2003, resumen; figuras. * |
| Base de Datos PAJ en EPOQUE: JP 2003124706 A (TOYOTA CHUO KENKYUSHO KK) 25.04.2003, resumen; figuras. * |
| Base de Datos PAJ en EPOQUE: JP 2003258667 A (MURATA MANUFACTURING CO) 12.09.2003, resumen; figuras. * |
| Base de Datos PAJ en EPOQUE: JP 55104103 A (HITACHI LTD) 09.08.1980, resumen; figuras. * |
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