Single-Ended and Balanced Flat-Group-Delay RF Low-Pass Filters With Input-Quasi-Reflectionless Behavior for Digital-Communication Systems
A class of RF low-pass filters (LPFs) simultaneously featuring flat-in-band-group-delay and input-quasi-reflectionless characteristics is reported for the first time. By means of a multilayered complementary-diplexer-based topology, a single-ended input-quasi-reflectionless LPF with in-band quasi-fl...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Alcalá (UAH) |
| Repositorio: | e_Buah Biblioteca Digital Universidad de Alcalá |
| Idioma: | inglés |
| OAI Identifier: | oai:ebuah.uah.es:10017/67131 |
| Acceso en línea: | http://hdl.handle.net/10017/67131 https://dx.doi.org/10.1109/TMTT.2024.3430485 |
| Access Level: | acceso abierto |
| Palabra clave: | Absorptive filter Balanced filter Common-mode (CM) suppression Coplanar stripline (CPS) Differential-mode (DM) filter Digital communications Eye diagram Group delay Linear-phase filter Low-pass filter (LPF) Reflectionless filter Signal integrity Transmission zero (TZ) Vertical transition Telecomunicaciones Telecommunication |
| Sumario: | A class of RF low-pass filters (LPFs) simultaneously featuring flat-in-band-group-delay and input-quasi-reflectionless characteristics is reported for the first time. By means of a multilayered complementary-diplexer-based topology, a single-ended input-quasi-reflectionless LPF with in-band quasi-flat group-delay response and multiple out-of-band transmission zeros (TZs) is first conceived. It consists of the combination of single-pole LPF units with resistively terminated microstrip-to-microstrip vertical slotline transitions (MS-to-MS VSTs). Subsequently, intrinsic common-mode-(CM)-signal suppression for its balanced counterpart is realized through in-series cascading two single-ended LPF stages with a coplanar stripline (CPS) section. As a result, a balanced LPF possessing differential-mode (DM) in-band quasi-constant group-delay response, DM input-quasi-absorptive behavior, and intrinsic CM suppression is obtained. Furthermore, to increase DM selectivity and out-of-band attenuation levels along with CM suppression levels, a higher rejection balanced LPF composed of multiple cascaded single-ended LPF units and CPS sections is also devised. The RF operating principles of the engineered single-ended and balanced LPF circuits are detailed. Three demonstrative prototypes-i.e., one single-ended and two balanced LPF circuits-are manufactured and characterized for practical validation purposes. For the higher rejection balanced LPF prototype, eye-diagram tests are also carried out to verify the quality/integrity of the transmitted DM signal in the time domain. |
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